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E. Draft Standards for Design and Construction 2015City af Kalispell Posit Office Box 1997 - Kalispell, Montana 59903 Telephone: (406) 758-7701 Fax- (406) 758-7758 To: Doug Russell, City Manager From: Susie Turner, Public Work Director Re Resolution of Intent and Call for Public Hearing on Amendment of the Kalispell Design and Construction Standards Meeting Date: March 2, 2015 BACKGROUND: Periodically, the City updates its, Standards for Design and Construction to ensure standards are in conformance with current requirements of the State and Federal agencies, to adopt changes in various material. and method used in construction, for standardization of materials, and to ensure the standards reflect the best practices necessary to support and maintain a vibrant and growing community. Several. changes have occurred since the last update; most notable is the formatting of the document to ensure each section is citable and more -user friendly for design and review. A new section implementing a review fee was added, along with the addition of section checklists to promote and ensure design submittals are complete. The update recommends the installation of water meter pits on new developments and for projects when services are replaced. Stormwater requirements for water quality treatment, flow control, and underground detention we're adjusted to allow for better stormwater management techniques to be utilized by the community, while still meeting the State stormwater regulatory requirements. Several other small changes have also been incorporated. All of the proposed changes have been circulated, throughout the local engineering, construction and development community. The comments received have been addressed, and where appropriate, incorporated into the present document. As part of the consideration of the standards amendment, notification and public hearing processes are applicable and will begin with the passage of the proposed resolution that establishes a date for the public hearing. ALTERNATIVES: Council can elect to not pass the resolution of intent, or proposi� modifications as council may RECOMMENDATION: It is recommended that council adopt the resolution calling for a public hearing on March 16, 2015, for the proposed amendment of the City of Kalispell Standards for Design, and Construction. ATTACHMENTS .- Draft 2015 Kalispell Design and Construction Standards CITY OF KALISPELL STANDARDS FOR DESIGN AND CONSTRUCTION April 6, 2015 TABLE OF CONTENTS TABLE OF CONTENTS CHAPTER 1- GENERAL PROVISIONS..............................................................................1 1.1 Standards......................................................................................................................................................................1 1.2 Public Right -of -Way Permit (Excavation Permit).....................................................................................................1 1.3 City Fees........................................................................................................................................................................2 1.4 Applicable Laws and Indemnification of City...........................................................................................................2 1.5 Interruption of Service................................................................................................................................................. 2 1.6 Traffic and Pedestrian Control................................................................................................................................... 3 1.7 Liability Insurance and Bonding................................................................................................................................ 4 1.8 Maintenance Bond for New Infrastructure................................................................................................................ 4 1.9 Excavation and Disposal of Material from Existing Public Right -of -Way and Easement ..................................... 5 1.10 Survey Monumentation................................................................................................................................................ 5 1.11 Pollution Controls......................................................................................................................................................... 5 1.12 Pavement Restoration.................................................................................................................................................. 6 1.13 Construction Inspection...............................................................................................................................................7 1.14 Guarantee for Equipment, Materials and Workmanship......................................................................................... 7 1.15 Stop Work Order.......................................................................................................................................................... 7 1.16 Relocation of Utilities...................................................................................................................................................7 CHAPTER 2 - CONSTRUCTION STANDARDS................................................................ 8 2.1 Project Requirements................................................................................................................................................... 8 2.2 Construction Standards...............................................................................................................................................8 2.3 Construction Inspection, Testing, and Quality Control............................................................................................ 9 2.4 Record Drawings and Project Acceptance...............................................................................................................10 2.5 Two -Year Guarantee Inspection...............................................................................................................................11 2.6 Boulevard Landscaping.............................................................................................................................................11 CHAPTER 3 - WATERISEWERISTREET DESIGN STANDARDS .............................12 3.1 Design and Development Requirements...................................................................................................................12 3.2 Water Systems............................................................................................................................................................ 14 3.3 Sanitary Sewer Systems.............................................................................................................................................17 3.4 Roadways and Walkways.......................................................................................................................................... 22 3.5 Driveways....................................................................................................................................................................27 3.6 Placement of Utilities.................................................................................................................................................. 27 3.7 Street Lighting............................................................................................................................................................ 27 3.8 Utility Easements........................................................................................................................................................ 29 3.9 Multiple Use Paths...................................................................................................................................................... 29 CHAPTER 4 - STORMWATER DESIGN...........................................................................30 4.1 INTRODUCTION...................................................................................................................................................... 30 4.1.1 OBJECTIVE AND PURPOSE...........................................................................................................................30 4.1.2 USING THE STORMWATER CHAPTER........................................................................................................ 30 4.1.3 GENERAL REQUIREMENTS.......................................................................................................................... 30 4.1.4 STANDARD OF CARE.....................................................................................................................................32 4.1.5 SEVERABILITY................................................................................................................................................32 4.2 BASIC REQUIREMENTS........................................................................................................................................32 4.2.1 INTRODUCTION.............................................................................................................................................. 32 4.2.2 BASIC REQUIREMENTS.................................................................................................................................35 4.3 DRAINAGE SUBMITTAL....................................................................................................................................... 43 4.3.1 INTRODUCTION.............................................................................................................................................. 43 4.3.2 APPLICABILITY...............................................................................................................................................43 4.3.3 DRAINAGE REPORT....................................................................................................................................... 43 4.3.4 ROAD AND DRAINAGE PLANS.................................................................................................................... 49 4.3.5 OTHER SUBMITTAL ELEMENTS.................................................................................................................. 51 4.4 GEOTECHNICAL SITE CHARACTERIZATION...............................................................................................51 4.4.1 INTRODUCTION.............................................................................................................................................. 51 4.4.2 APPLICABILITY...............................................................................................................................................52 4.4.3 GEOTECHNICAL SITE CHARACTERIZATION REPORT...........................................................................52 TABLE OF CONTENTS 4.5 HYDROLOGIC ANALYSIS AND DESIGN........................................................................................................... 58 4.5.1 INTRODUCTION.............................................................................................................................................. 58 4.5.2 HYDROLOGIC ANALYSIS METHODS......................................................................................................... 58 4.5.3 CURVE NUMBER METHOD........................................................................................................................... 58 4.5.4 LEVEL POOL ROUTING METHOD................................................................................................................ 71 4.5.5 RATIONAL METHOD...................................................................................................................................... 71 4.6 WATER QUALITY TREATMENT DESIGN........................................................................................................ 75 4.6.1 INTRODUCTION.............................................................................................................................................. 75 4.6.2 WATER QUALITY PROTECTION STANDARDS.........................................................................................76 4.6.3 TREATMENT BMPS.........................................................................................................................................76 4.7 FLOW CONTROL...................................................................................................................................................107 4.7.1 INTRODUCTION............................................................................................................................................107 4.7.2 APPLICABILITY.............................................................................................................................................108 4.7.3 DETENTION FACILITIES..............................................................................................................................108 4.7.4 OUTFLOW CONTROL STRUCTURES.........................................................................................................109 4.7.5 INFILTRATION FACILITIES.........................................................................................................................119 4.7.6 UNDERGROUND DETENTION FACILITIES..............................................................................................123 4.7.7 RETENTION FACILITIES..............................................................................................................................124 4.7.8 ADDITIONAL REQUIREMENTS FOR ALL FACILITIES........................................................................124 4.7.9 PLANTING REQUIREMENTS....................................................................................................................128 4.7.10 LANDSCAPING.............................................................................................................................................128 4.7.11 SPECIAL REQUIREMENTS...........................................................................................................................129 4.7.12 REGIONAL DETENTION PONDS................................................................................................................130 4.8 NATURAL AND CONSTRUCTED CONVEYANCE SYSTEMS ......................................................................131 4.8.1 INTRODUCTION............................................................................................................................................131 4.8.2 APPLICABILITY.............................................................................................................................................131 4.8.3 NATURAL AND CONSTRUCTED CHANNELS..........................................................................................131 4.8.4 CULVERTS......................................................................................................................................................140 4.8.5 STORM DRAIN SYSTEMS............................................................................................................................144 4.8.6 GUTTERS........................................................................................................................................................148 4.8.7 DRAINAGE INLETS.......................................................................................................................................151 4.9 EROSION AND SEDIMENT CONTROL DESIGN............................................................................................155 4.9.1 INTRODUCTION............................................................................................................................................15 5 4.9.2 APPLICABILITY.............................................................................................................................................156 4.9.3 EROSION AND SEDIMENT CONTROL (ESC) PLAN................................................................................157 4.9.4 STORMWATER MANAGEMENT PERMIT.................................................................................................164 4.10 MAINTENANCE, PARCELS, AND EASEMENTS.............................................................................................168 4.10.1 MAINTENANCE.............................................................................................................................................168 4.10.2 PARCELS AND EASEMENTS.......................................................................................................................172 TABLE OF CONTENTS APPENDICES: APPENDIX A - CHECKLIST FOR IDENTIFYING WETLANDS ...........................174 APPENDIX B1- SWALE FLOOD TEST.........................................................................176 APPENDIX B2 - POND FLOOD TEST...........................................................................176 APPENDIX C - BMP T5.100 API (BAFFLE TYPE) SEPARATOR BAY..................177 APPENDIX D - FLOW SPREADER OPTIONS..............................................................179 APPENDIX E - FILTER STRIPS USED FOR PRE-TREATMENT.............................185 APPENDIX F - PLANTING GUIDELINES......................................................................187 APPENDIX G1- EXAMPLE CALCULATION: ............................................................... 192 APPENDIX G2 - EXAMPLE CALCULATION: ............................................................... 193 APPENDIX H1- FACILITY MAINTENANCE RECOMMENDATIONS ....................195 APPENDIX H2 - FACILITY INSPECTION CHECKLIST ............................................. 204 APPENDIX H3 - EXAMPLE MAINTENANCE AGREEMENT .................................... 205 ADDITIONAL RESOURCES: ABBREVIATIONS AND ACRONYMS............................................................................. 207 GENERAL STANDARD DRAWINGS AND NOTES ...................................................... 208 WATER SYSTEM STANDARD DRAWINGS AND NOTES ......................................... 210 SANITARY SEWER STANDARD DRAWINGS AND NOTES ..................................... 215 STORM SEWER STANDARD DRAWINGS AND NOTES ........................................... 220 STREET STANDARD DRAWINGS AND NOTES......................................................... 224 SPECIAL PROVISIONS SECTION 02600 WATER DISTRIBUTION SPECIAL PROVISIONS SECTION 02720 STORM DRAIN SYSTEMS SPECIAL PROVISIONS SECTION 02730 SANITARY SEWER COLLECTION SYSTEM GENERAL REVIEW CHECKLIST WATER REVIEW CHECKLIST WATER REVIEW CHECKLIST SANITARY REVIEW CHECKLIST STREET REVIEW CHECKLIST STORMWATER REVIEW CHECKLIST ff TABLE OF CONTENTS TABLE OF FIGURES Figure 1 - Unit peak discharge (qu) for NRCS (SCS) type I rainfall distribution ................................. 70 Figure2 - Wetpond Details.................................................................................................................... 82 Figure3 - Wet Pond Plan View............................................................................................................. 84 Figure4 - Wet Pond Profiles................................................................................................................. 85 Figure 5 - Biofiltration Swale Schematic............................................................................................... 90 Figure 6 - Biofiltration Swale Underdrain Detail for Slopes <2%........................................................ 90 Figure 7 - Bioretention Area.................................................................................................................. 98 Figure 8 - Bioretention Area Off-line Schematic.................................................................................. 99 Figure 9 - Dry Swale Cross Section..................................................................................................... 105 Figure 10 - Dry Swale Plan View........................................................................................................ 105 Figure 11 - Dry Swale Profile ........................................ Figure 12 - Example Outflow Control Structure................................................................................. 110 Figure 13 - Detention Facility Outflows.............................................................................................. 111 Figure 14 - Flow Restrictor Baffle....................................................................................................... 113 Figure 15 - Flow Restrictor (Tee)........................................................................................................ 114 Figure 16 - Skimmer (with baffle wall)............................................................................................... 115 Figure17 - Skimmer............................................................................................................................ 116 Figure 18 - Flow Equations for Various Weir and Orifice Types ....................................................... 117 Figure 19 - Flow Rates vs. Head (riser)............................................................................................... 118 Figure 20 - Infiltration Facility Details................................................................................................ 122 Figure 21 - Riprap Revetment at Outfall Schematic............................................................................ 136 Figure 22 - Non -Flooded Road Width(L)........................................................................................... 148 Figure 23 - Uniform Gutter Section..................................................................................................... 150 Figure 24 - Typical Grate Inlet Cross-Section..................................................................................... 153 M TABLE OF CONTENTS LIST OF TABLES Table 1 - Road Design Standards for Local Subdivision Streets........................................................... 26 Table2 - FEC's Standards...................................................................................................................... 28 Table 3 - Owner Metered/Maintained.................................................................................................... 28 Table 4 - Allowable Discharge Rates.................................................................................................... 40 Table 5 - Example Sub -level Structure Feasibility Summary............................................................... 57 ....................... Table 6 - Curve Numbers Based on Antecedent Runoff Conditions (ARC)[][] ..................................... 62 Table 7 - Runoff Curve Numbers Antecedent Runoff Conditions (ARC) II ......................................... 63 Table 8 - Friction Values n and k For Use In Computing Time of Concentration[][] .......................... 67 Table 9 - Suggested Values of Manning's Roughness Coefficient "n" For Channel Flow 11................ 68 Table 10 - City of Kalispell 24-Hour Precipitation Depths................................................................... 69 Table 11 - Frequency Factors for Rational Formula.............................................................................. 72 Table 12 - Recommended Coefficient of Runoff for Pervious Surfaces by Selected Hydrologic Soil Groupings and Slope Ranges 11............................................................................................ 73 Table 13 - Recommended Coefficient of Runoff Values for Various Selected Land Uses 11................ 74 Table 14 - Maximum Infiltration Rates for Soil Types......................................................................... 79 Table 15 - Wetland Protection Standards1l (Stormwater Quality Management Plan) ......................... 106 Table 16 - Allowable Discharge Rates................................................................................................ 108 Table 17 - Permissible Velocities for Channels with Erodable Linings,Based on Uniform Flow in Continuously Wet, Aged, Channels 11................................................................................ 133 Table 18 - Manning's Roughness Coefficient (n) For Culverts.......................................................... 141 Table 19 - Minimum Culvert Sizes...................................................................................................... 141 Table 20 - Manning's Roughness Coefficient (n) For Closed Systems ............................................... 145 Table 21 - Non -Flooded Road Width Requirements........................................................................... 149 Table 22 - Manning's Roughness Coefficients (n) for Street and Pavement Gutters[' ........................ 150 Table 23 - Allowable Width and Perimeter for Grate Capacity Analysis ........................................... 154 v CHAPTER 1 — GENERAL PROVISIONS Chapter 1— General Provisions 1.1 STANDARDS 1.1.1 The latest published edition of the Montana Public Works Standard Specifications are adopted in their entirety, except as amended by the latest edition of the City of Kalispell Standards for Design and Construction. With respect to the design and/or construction of public facilities, any conflict(s) or difference(s) between the Montana Public Works Standard Specifications, the City of Kalispell Subdivision Regulations, and the City of Kalispell Standards for Design and Construction shall be resolved in favor of the City of Kalispell Standards for Design and Construction. 1.1.2 New construction will be built under the Standards for Design and Construction in effect at the time of construction. 1.1.3 If construction of approved plans is not completed within 18 months from the date of design approval, and updates to the Standards for Design and Construction have occurred since the date of approval, the design plans, specifications, and reports shall be resubmitted for City review and approval. City review fees for additional reviews of previously approved plans shall be waived. 1.2 PUBLIC RIGHT-OF-WAY PERMIT (EXCAVATION PERMIT) 1.2.1 All construction, excavation or other work on public or private property which will necessitate the use of the public right-of-way or easement shall require a Public Right -of - Way Permit issued by the Public Works Department. The work authorized by the Permit includes, but is not limited to, street construction and repair, water, sewer, and storm system construction and repair, utility connections and repair, landscaping, sidewalk, curbing and driveway construction and repair. Also included are any other uses of the public right-of-way where there is a possibility of creating a hazard. Examples of hazards are scaffolding, storage of materials or equipment, crane and equipment operations, demolition, sandblasting and painting operations, temporary construction or demolition dumpster placement and any other use deemed a hazard by the Public Works Department. The Permit will not be issued until all insurance and bonding requirements have been met. 1.2.2 In an emergency which requires repairs to be made immediately, the Contractor may excavate and complete the repairs without first having obtained a Permit. Prior to beginning work at the site during normal working hours, the Contractor shall notify the Public Works Department at 758-7720. Prior to beginning work after hours, the Contractor shall notify police dispatch at 758-7780. In either case, the Contractor shall describe the circumstances and provide the location of the emergency repairs. The Contractor shall obtain the Permit no later than the next scheduled City work day. 1.2.3 All provisions of the Standards for Design and Construction for the City of Kalispell, Montana, shall be complied with regardless of the circumstances of the construction. CHAPTER 1 — GENERAL PROVISIONS 1.2.4 All steel tracked equipment operating within a public street right-of-way shall be fitted with triple grouser street pads. The Contractor shall be responsible for damages to City infrastructure within the public street right-of-way. 1.3 CITY FEES 1.3.1 Water & Sewer Service Connection Fee (Impact Fees) A connection fee shall be paid for the connection of each new water and sewer service to the system. This fee must be paid even if a service line has previously been stubbed to the property line or other accessible location. Connection fees for water and/or sewer must be paid before a Building Permit will be issued by the Building Department and before service is approved. Impact fees may be paid in installments as established by City Ordinance. 1.3.2 Construction of Water Service. When it is necessary to tap an existing water main for a service connection: the Contractor will excavate around the main and prepare a safe trench from the main to the approved curb stop location; the City will provide the equipment, labor and materials required to tap the main and install the service line from the main to the curb stop valve; the Contractor will install backfill, and restore the pavement surface. The City will charge the Owner for equipment, labor and materials required to complete the work. The Owner will be responsible to construct the service line from the curb stop to the point of service. 1.3.3 Construction of Sewer or Storm Service. When it is necessary to tap an existing sewer or storm main for a service connection, the Contractor will provide the equipment, labor and materials required to tap the main, install the service line from the main to the point of use and restore the public right of way to the pre -construction condition meeting minimum City Standards. City personnel shall inspect the tap prior to backfill. 1.4 APPLICABLE LAWS AND INDEMNIFICATION OF CITY 1.4.1 The Contractor shall give all notices and comply with all federal, state and local laws, ordinances and regulations affecting the conduct of the work, and shall indemnify and hold harmless the City against any claim or liability arising from, or based on, the violation of any such law, ordinance, regulation, etc., whether by himself or his employees. 1.5 INTERRUPTION OF SERVICE 1.5.1 Any construction that will interrupt the normal operation of city sewer, water, storm or transportation facilities requires notification of affected City departments and property owners and/or residents. The Contractor shall notify the Kalispell City Police and Fire Departments at least forty-eight (48) hours prior to any street closures. All street closures or interruptions of utility services will require the Contractor to provide a news release specifying the location of construction and the duration of the closure. The Contractor shall present the news release to the news media at least two (2) work days prior to the beginning of any construction activity. The Contractor shall also notify utility users affected by the interruption of the type and duration of the interruption at least forty-eight (48) hours prior to beginning construction. 2 CHAPTER 1 — GENERAL PROVISIONS 1.6 TRAFFIC AND PEDESTRIAN CONTROL 1.6.1 In the event of an emergency interruption, the Contractor shall notify the Public Works, Police and Fire Departments immediately. The Contractor shall immediately dispatch members of his staff to notify affected individuals by telephone or personal contact.Traffic and Pedestrian Control 1.6.2 A Traffic and Pedestrian Control Plan shall be submitted to and approved by the Public Works Department for all work within the public right-of-way. The latest edition of the Manual on Uniform Traffic Control Devices (MUTCD) shall be followed to create the Plan. The location and description of all Traffic and Pedestrian Control Devices shall be shown on the plan. All signs shall comply with the MUTCD for size, type, placement, material and reflectivity. The plan must be approved prior to beginning construction. If the required devices are not in place, the Contractor will not be allowed to begin work on the project. All devices shall be kept in place and maintained in good visible condition throughout the project. The Public Works Department reserves the right to reject any device observed to be in substandard condition. 1.6.3 Emergency access to the work area shall be maintained at all times. 1.6.4 All barricades and obstructions shall be protected at night by suitable signal lights which shall be kept illuminated from sunset to sunrise. Barricades shall be of substantial construction and shall be constructed to increase their visibility at night. Suitable warning signs shall be placed to show in advance where construction, barricades or detours exist. All signs used at night shall be either retro-reflective with a material that has a smooth, sealed outer surface or illuminated to show the same shape and similar color both day and night. 1.6.5 If flagging is required it shall be accomplished by competent and properly equipped flag persons. Flagging shall be accomplished as described in the Montana Department of Transportation Flagger's Handbook and the MUTCD. 1.6.6 Traffic control devices shall be removed from visual contact with the traveling public when they are not being used for construction activities. 1.6.7 The Contractor shall remove all traffic and pedestrian control devices within 24 hours of the conclusion of the project construction. 1.6.8 If the Contractor fails to maintain the Traffic and Pedestrian Control Devices in accordance with the approved plan, the City reserves the right to correct the deficiency and all labor, equipment, material and administrative costs will be billed to the Contractor. 3 CHAPTER I — GENERAL PROVISIONS 1.7 LIABILITY INSURANCE AND BONDING 1.7.1 Liability Insurance for Work Within Existing Public Right -of -Way and/or Easement. A. The Contractor shall procure and maintain, at the Contractor's expense, during the construction period, Contractor's Liability Insurance in accordance with the Supplementary Conditions to the General Conditions of the Montana Public Works Standard Specifications. 1.7.2 Performance Bond A. All construction work within the public right-of-way or easement (sidewalk, boulevard, pavement, curb construction, water, storm drainage, sanitary sewer service line installation, repair, etc.) will require the Property Owner/Contractor to provide the City with a Performance Bond. The bond shall be equal to the value of the project and shall remain in force for one year. Contractors annually furnishing the City with a two year bond of $5,000 will not be required to furnish additional bonding if the $5,000 bond meets the requirements of these standards. B. Bonds may be in the form of a Surety Bond, a Certificate of Deposit (CD), a Certified Check or an irrevocable Letter of Credit issued by a bank licensed to do business in the state of Montana. 1.8 MAINTENANCE BOND FOR NEW INFRASTRUCTURE 1.8.1 See 1.14 Guarantee for equipment, materials and workmanship. 1.8.2 As a condition precedent to the filing of a final plat, or the issuance of the Certificate of Occupancy, the Property Owner, Developer, or Contractor shall provide the City with a Maintenance Bond of twenty percent (20%) of the total value of the public infrastructure constructed within the subdivision, development, or phased development. The Maintenance Bond shall remain in full force for a two-year period after acceptance of the entire City infrastructure by the City for maintenance. The City expressly reserves the right to draft the Maintenance Bond for repairs not completed by the Property Owner, Developer, or Contractor within thirty calendar days of being advised that repairs are required. 1.8.3 The Commencement Date for the Maintenance Bond shall be the date set for the completion of the required improvements as stated in the Subdivision Improvements Agreement, the date of Substantial Completion as certified by a Professional Engineer, or the date Final Plat is granted, whichever is Later. If the expiration date of the Maintenance Bond falls after November 16, the expiration date of the Maintenance Bond shall be June 30 of the following year. 1.8.4 Maintenance bonds may be in the form of a Surety Bond, a Certificate of Deposit (CD), a Certified Check or an irrevocable Letter of Credit issued by a bank licensed to do business in the state of Montana. 4 CHAPTER 1 — GENERAL PROVISIONS 1.9 EXCAVATION AND DISPOSAL OF MATERIAL FROM EXISTING PUBLIC RIGHT- OF-WAY AND EASEMENT 1.9.1 All material unsuitable for trench backfill, sub -base or base construction, excavated from the developed public right-of-way or easement shall be removed from the site and disposed of by the Contractor. The disposal site shall meet regulatory provisions for disposal of the unsuitable excavated material. Unsuitable excavated material shall not be stockpiled on site without the written approval of the Public Works Department. Excavated material shall be confined to the work zone as established during the preconstruction conference or as shown in the contract documents. 1.10 SURVEY MONUMENTATION 1.10.1 When a street is to be reconstructed, prior to any excavation, a thorough search shall be made for existing intersection monuments. If found, such monuments and any other survey monuments likely to be disturbed or destroyed, shall be preserved by or under direction of a Professional Land Surveyor in accordance with MCA 70-22-115. 1.10.2 All monuments set shall meet the requirements of ARM 24.183.1101. Monuments set in pavement or concrete driving surfaces shall be placed inside of a cast iron monument box. 1.11 POLLUTION CONTROLS 1.11.1 The Contractor shall be responsible to maintain the construction site and all haul routes in accordance with the requirements of the City of Kalispell's Emission Control Plan (see City Ordinance No. 1139). The Contractor shall obtain a County Air Qualily Construction/Demolition Permit prior to beginning construction. The Contractor shall obtain a Construction Stormwater Management Permit for any land disturbance in the City of Kalispell. 1.11.2 No sediment laden or polluted water shall be discharged off any construction or building site. A City Construction Stormwater Management Permit for construction sites is required for land -disturbing activities which include, but are not limited to, excavation, planting, tilling, and grading, which disturbs the natural or improved vegetative or developed ground cover so as to expose soil to the erosive forces of rain, stormwater runoff or wind. All installations and maintenance of franchise utilities such as telephone, gas, electric, etc., shall be considered land disturbing activities. CHAPTER I — GENERAL PROVISIONS 1.11.3 The following land -disturbing activities require a City Stormwater Management Permit: A. Any activity where the total volume of material disturbed, stored, disposed of or used as fill exceeds five (5) cubic yards; or, B. Any activity where the area disturbed exceeds one thousand (1,000) square feet provided it does not obstruct a watercourse, and is not located in a floodplain. 1.11.4 The Construction Stormwater Management Plan shall adhere to Ordinance 1600 and be submitted prior to any land -disturbing activity. For detailed information on the City Stormwater Management Permit refer to Chapter 4. 1.12 PAVEMENT RESTORATION 1.12.1 The Contractor signing the Public Right -of -Way Permit shall be responsible for pavement replacement. The Contractor shall restore all surfaces within fourteen (14) calendar days after completing the backfill work. 1.12.2 All new roads or reconstructed roads shall be paved with a minimum of 4"of Type B asphalt and shall be accomplished in accordance with current Montana Public Works Standard Specifications. 1.12.3 The pavement restoration shall match the pavement structure thickness as shown on Standard Drawings SD-1 through SD-4. All excavations within 48" of the edge of the asphalt (including the outer edge, the crown, or adjacent seam) shall require removal and replacement from the edge of asphalt to the excavation edge. Asphalt patch areas that fall within the wheel path of the vehicular travel lane shall be increased in size to the center of the lane or adjacent lane. In no circumstance will the edge of a patch area be allowed to fall within the wheel path. 1.12.4 Any damage to the existing asphalt surface caused by the Contractor's operations shall be repaired at the expense of the Contractor, including but not limited to gouges, scrapes, outrigger marks, backhoe bucket marks, etc. A slurry seal will be considered the minimum standard for a repair to existing surfacing. 1.12.5 The Contractor shall be responsible for maintaining the area in a smooth and drivable condition until the permanent pavement is placed. If the ground is frozen, the road cut shall be temporarily repaired with a minimum thickness of two (2) inches of cold patch material. The temporary repair shall be maintained by the Contractor for safe winter usage. The permanent restoration shall be made as soon as the ground is thawed in the spring, or as directed by the Public Works Department. Pavement repairs shall be in accordance with the Standards for Design and Construction. 1.12.6 If the Contractor fails to restore the pavement within the fourteen day period, or fails to maintain the trench or area as required, the City reserves the right to complete the restoration or maintenance, and all labor, equipment, material and administrative costs will be billed to the Contractor. The City reserves the right to call on the Contractor's Performance Bond if the bill is not paid within 30 days. 6 CHAPTER 1 — GENERAL PROVISIONS 1.13 CONSTRUCTION INSPECTION 1.13.1 Maintenance and repair work within public right-of-way or easement shall be inspected and approved by the Public Works Department. It is the Contractor's responsibility to notify the Public Works Department of the work requiring inspection at least twenty-four (24) hours in advance so the Public Works Department may schedule and perform such inspections. 1.14 GUARANTEE FOR EQUIPMENT, MATERIALS AND WORKMANSHIP 1.14.1 See 1.8 Maintenance bond for new infrastructure. 1.14.2 The Contractor shall guarantee all materials and equipment furnished, and construction work performed for maintenance and repair work on existing public infrastructure for a period of one (1) year from the date of written acceptance of the work by the City. 1.14.3 The guarantee for new City infrastructure shall be for a period of two (2) years from the date of written acceptance of the work by the City. In the case of a subdivision, the date of acceptance will be final plat approval or acceptance by the Public Works Department, whichever is later. 1.15 STOP WORK ORDER 1.15.1 A written Stop Work Order maybe issued by the Public Works Department if the maintenance and repair work in progress does not meet the Standards for Design and Construction for the City of Kalispell, or for any other valid reason. Work may resume only after a written Resume Work Order has been issued by the Public Works Department. 1.16 RELOCATION OF UTILITIES 1.16.1 Requests to relocate an existing public utility shall be submitted in writing to the Public Works Department. A sketch shall be included that illustrates the existing location of the utility and the preferred relocation site. The request shall describe in detail the circumstances for the request. The Public Works Department may require the utility relocation to be designed by a licensed engineer. If the relocation is approved by the Public Works Department the utility shall be relocated by a bonded and insured utility contractor (See Section 1.7). Under no circumstances will the City of Kalispell pay for any costs associated with the relocation of the utility. Relocation of water and sewer may also be subject to Montana Department of Environmental Quality review and approval. 7 CHAPTER 2 — CONSTRUCTION STANDARDS Chapter 2— Construction Standards 2.1 PROJECT REQUIREMENTS 2.1.1 Contractors installing water mains, sanitary sewer mains, storm sewer mains and roadways or any other public improvements shall be subject to the following requirements: A. Construction Contractor Registration. Any Contractor working within an existing Public Right -of -Way or Easement shall be registered with the Montana Department of Labor and Industry, Employment Relations Division. B. Insurance and Bonding. Insurance and bonding shall be in accordance with Sections 1.7 and 1.8 as applicable. C. Pre -Construction Conference. Prior to any construction start, a preconstruction conference shall be held. The Public Works Department, the Project Engineer, the geotechnical firm, the traffic control, the Owner, and the Contractor, and any other parties pertinent to the project shall be represented. Items to be discussed at the pre -construction conference are construction schedule, shop drawing submittals, utility installation, materials testing, quality control, maintenance bond, and other items as may be necessary. D. Shop Drawing Submittal. If the proposed items to be installed differ from the approved plans and specifications, shop drawings shall be submitted for review not later than ten (10) business days prior to the proposed installation. 2.2 CONSTRUCTION STANDARDS 2.2.1 All water, sanitary sewer, storm drainage, and roadway systems, or any other construction of infrastructure within the public right-of-way or easement, shall be constructed, inspected, and tested in accordance with the current edition of The Montana Public Works Standard Specifications and the Standards for Design & Construction of the City of Kalispell and other standards referenced elsewhere in this document. With respect to the design and/or construction of public facilities, any conflict(s) or difference(s) between the Montana Public Works Standard Specifications, the City of Kalispell Subdivision Regulations, and the City of Kalispell Standards for Design and Construction shall be resolved in favor of the City of Kalispell Standards for Design and Construction. 2.2.2 Underground Utilities. All underground electrical, gas, phone, and TV cable lines must be installed at least three (3) feet horizontally from water, sanitary sewer and storm sewer mains and services. 8 CHAPTER 2 — CONSTRUCTION STANDARDS 2.3 CONSTRUCTION INSPECTION, TESTING, AND QUALITY CONTROL 2.3.1 A Professional Engineer, or the Professional Engineer's designated representative, shall provide construction inspection and testing as required. Inspection and testing shall be in accordance with the current edition of the Montana Public Works Standard Specifications and the Standards for Design and Construction. 2.3.2 The following quality control procedures will apply to all utility and roadway construction projects. The City reserves the right to conduct independent quality assurance testing at the City's expense during any phase of the construction. The Contractor shall bear the expense of failed tests and the expense of bringing the material into conformance with the required specifications. A. All water main valves and fittings, fire hydrants, sewer manholes, wet wells and sewer/water main crossings shall be inspected and approved by the Professional Engineer, or his designated representative, prior to backfilling. B. A Professional Engineer, or the Professional Engineer's designated representative, shall be present for all tests required in Section 02660 and Section 02730 of the Montana Public Works Standard Specifications. A written record of all test results shall be submitted to the Public Works Department. C. A Professional Engineer, or the Professional Engineer's designated representative, shall provide the Public Works Department with photocopies of daily inspection reports, including Proctors and compaction test results for all projects. These reports shall be submitted on a weekly basis. 2.3.3 The following minimum compaction testing procedures shall apply to all utility and roadway construction projects. An independent accredited testing laboratory shall be retained to provide the following tests and frequency. Random longitudinal test locations are required. The following are minimum compaction test requirements. The Professional Engineer, or the Professional Engineer's designated representative, may require additional tests. For projects containing less than 300 linear feet of improvements, a minimum of one compaction test for each improvement shall be required for the improvements listed below. A. Utility Trenches and Underground Structures: 1. For trenches up to eight (8) feet in depth, density tests shall be taken at twelve (12) inches above the pipe; at one-half the trench depth; and at the surface. For trenches greater than eight (8) feet in depth, density tests shall be taken at twelve (12) inches above the pipe, at one-third and two -third the trench depth levels, and at the surface. g CHAPTER 2 — CONSTRUCTION STANDARDS I1. The minimum density shall be 95% Standard Proctor, f 3% optimum moisture. a. Horizontal Frequency: i Utility Mains — One set of tests per 300 feet. ii Service Lines — One set of tests per three (3) services per utility type. iii Open Pit — Minimum of one test (Open Pit — at each manhole, water valve, storm inlet, curb inlet, vault, etc.) b. Each test location shall be separated horizontally from a prior test location. B. Street sub grade: I. All sub -base: 95% Standard Proctor, f 3% optimum moisture. One random density test, every 300 linear feet of street. II. All crushed gravel base: 95% Standard Proctor, f 3% optimum moisture. One random density test, every 300 linear feet of street. 2.3.4 Television Inspection. A. The City of Kalispell reserves the right to inspect all underground utility systems by the use of a television camera prior to final acceptance. The City will perform the initial inspection at no cost to the contractor. If the City is required to clean debris, gravel, etc. from the line in order to perform the TV inspection, the costs for the cleaning services will be billed to the Contractor. Any deficiencies found by the initial TV inspection shall be corrected by the contractor. The cost of the additional TV testing required to ensure the deficiencies have been corrected will be billed to the Contractor. 2.4 RECORD DRAWINGS AND PROJECT ACCEPTANCE. 2.4.1 Upon project completion and before final acceptance, a Professional Engineer shall certify to the City that the construction of the water, sewer and storm utilities and roadways meet the requirements of the approved construction documents. The Engineer shall submit one full-size set of record drawings (hard copy and DWG digital format) and one set of the test results as required under Section 2.3 of these standards to the Public Works Department. The City will not accept the project until record drawings and test results have been approved by the City Engineer. The two-year maintenance guarantee period will begin on the date stated in accordance with Section 1.8. The Project Engineer shall provide quantities and unit costs of all City -owned infrastructure. 10 CHAPTER 2 — CONSTRUCTION STANDARDS 2.5 TWO-YEAR GUARANTEE INSPECTION. 2.5.1 The Project Engineer, or his designated representative, shall conduct a two-year guarantee inspection, to be attended by a representative from the Public Works Department. The inspection shall take place not less than ninety (90) days prior to the expiration date of the Maintenance Bond. The maintenance bond will be released when all deficiencies have been corrected to the satisfaction of the City Engineer. 2.5.2 The City Engineer, the Project Engineer, or the designated representative, shall notify the Principal as listed in the Maintenance Bond of any work found to be not in accordance with the approved construction documents. The Principal shall restore the work to meet the requirements of the approved construction documents prior to the release of the Maintenance Bond. The City expressly reserves the right to draft the Maintenance bond for repairs not completed by the Owner, Developer, or Contractor within thirty calendar days of being advised that repairs are required. 2.6 BOULEVARD LANDSCAPING. 2.6.1 The Contractor shall place a minimum of four (4) inches of topsoil within the boulevard. The finished surface of the topsoil shall provide adequate drainage from the top of the sidewalk to the top of the curb. Topsoil shall be fertile, natural loam surface soil, free of clay, weeds, roots or stones larger than one inch in any dimension. Boulevard landscaping shall be placed in accordance with the Kalispell Street Tree Ordinance and a plan approved by the Kalispell Parks and Recreation Department. CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS Chapter 3 — Water/Sewer/Street Design Standards 3.1 DESIGN AND DEVELOPMENT REQUIREMENTS. 3.1.1 The purpose of these standards is to establish the minimum requirements for the design and construction of municipal facilities and improvements that impact municipal facilities. 3.1.2 Design Requirements A. All water, sanitary sewer, storm drainage and roadway systems necessary to provide service to and within a development shall be constructed at the Developer's expense and shall be designed by a Professional Engineer licensed in the State of Montana. Plans, specifications and design reports shall bear the seal of the Engineer in responsible charge of the design. B. Water and sanitary sewer system designs shall be reviewed concurrently by the City Engineer and the Montana Department of Environmental Quality, with approval of both required. Storm drainage and roadway designs shall be submitted to and approved by the City Engineer. All required approvals shall be obtained prior to beginning construction. Design calculations shall be approved prior to construction. Testing results shall be submitted to the City Engineer as required or requested. 3.1.3 Review Fee A. Prior to review of plans, specifications and design reports, a Plan Review Fee of $180.00 shall be submitted to the Department of Public Works. B. An additional fee of $180 will be required prior to each successive plan review. C. The Professional Engineer submitting plans, specifications, and/or design reports for review shall complete the pertinent checklists provided in the back of the manual and stamp the cover sheet. 3.1.4 Responsibilities A. The Professional Engineer stamping the plans for design of any publicly owned infrastructure is responsible to meet the minimum design standards as specified or referenced herein. If at any point of design or construction, an unapproved deviation from the standards is realized by the Engineer, Contractor, or the City, immediate action shall be taken to correct the issue and bring the design or construction into compliance with the standards currently in effect at no cost to the City. All changes from approved drawings shall be reviewed and accepted in writing by the Public Works Engineering staff, prior to construction. 12 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS B. The Contractor performing the construction of publicly owned infrastructure is responsible to meet the minimum construction standards as specified or referenced herein. If at any point of design or construction, an unapproved deviation from the standards is realized by the Engineer, Contractor, or the City, immediate action shall be taken to correct the issue and bring the design or construction into compliance with the standards currently in effect at no cost to the City. All changes from approved drawings shall be reviewed and accepted in writing by the Public Works Engineering staff, prior to construction. C. The City Engineering staff is responsible to review the design and construction to verify compliance with current standards. The approval of reviewed design plans, reports and/or specifications does not relieve the Professional Engineer from meeting minimum design standards as specified or referenced herein. The approval of reviewed construction does not relieve the contractor from meeting minimum construction standards as specified or referenced herein. 3.1.5 Design or Construction Deviation A. Design or construction deviations will only be granted when minimum standards cannot be met or when the proposed item exceeds minimum standards as determined by the City Engineer. Deviations will not be considered on basis of cost, "Engineering judgment" or "professional opinion". B. A person desiring a deviation shall make a request in writing. The request must identify the specific section of the standards to be considered. Adequate justification for the deviation must be provided. C. All deviations must be approved by the City of Kalispell Public Works Engineering Staff in writing. 3.1.6 Municipal Facilities Exclusion (MFE) A. An MFE is required by DEQ prior to construction. The City's MFE approval and all capacity allocations shall expire with the expiration of DEQ's original design approval for construction. This requirement shall be applicable to all designs submitted after the date of adoption of these Standards. 3.1.7 Development Requirements A. All subdivisions and developments shall be in compliance with The Subdivision Regulations of the City of Kalispell, and these Standards for Design and Construction. B. It shall be the responsibility of the Developer to construct all roadways and utilities from the existing facilities to the far property line of the development or such other point within the development that may be specified by the City Engineer. All utilities shall be within a public right-of-way or easement to permit free and unobstructed access. 13 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS C. It is the Developer's responsibility to obtain and provide the City with all easements and right-of-ways necessary to extend roadways and utilities to the far property line of the development. The Developer shall obtain written approval from the Kalispell Public Works Department stating they have reviewed and approved the location of easements for the future extension of roadways and utilities which shall be submitted with the final plat along with an 11" by 17" legible copy of the approved final plat showing the utility and/or easement locations. D. There shall be reserved along the front lot line and side street lot line of each residential and commercial lot a ten -foot (10') wide utility easement along, contiguous and adjacent to the lot line to provide an area between the lot line and the easement line for the placement of privately owned underground utilities. I. All new utilities shall be placed underground. II. City utility collection and distribution mains shall be located within the paved portion of the street or alley. III. Water transmission mains and sewer interceptor mains shall be located as approved by the City Engineer. IV. Underground private utilities shall be located on private property between the lot line and the easement line. V. No underground utilities, except service sweeps to the street lights shall be placed parallel to the roadway in the boulevard between the back of curb and sidewalk or within a sidewalk itself. VI. No above -ground utility boxes, pedestals, vaults, or transformers shall be placed within any easement, proposed roadway, or access way to any City facility. VII. Street lights shall be at least two (2) feet from the back of curb. All above ground utilities shall be at least one (1) foot from the sidewalk. E. Site plans, grading plans, and elevations used for infrastructure work shall be based on the North American Vertical Datum 1988. Site plans, projects, designs, and surveys conducted on City property or paid for with City funding shall be based on and utilize the Montana State Plane Coordinate System (International Feet). 3.2 WATER SYSTEMS 3.2.1 Water systems shall be designed, constructed, and tested in accordance with the current editions of the Montana Department of Environment Quality - Circular DEQ 1 -Standards for Water Works, the Montana Public Works Standard Specifications, and the Standards for Design and Construction, Kalispell, Montana. 14 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.2.2 Design Report. All water main extensions require the Design Engineer to submit a written report to the City Engineer which addresses the fire and domestic now requirements. The report shall include flow test results at a hydrant nearest to the development, as approved by Public Works staff, which shows the static pressure at zero flow from the hydrant and the available flow from the hydrant at 20 psi residual pressure. The City will perform the required hydrant flow testing and will provide the test data to the Design Engineer, at no cost, if so requested. The Design Engineer shall be limited to a single hydrant flow test per development per year, unless otherwise approved by the City Engineer. 3.2.3 Isolation Valves. Isolation valves shall be installed at each leg of each tee or cross, and at each crossing of an intersection. Distance between isolation valves shall not exceed 500 feet, unless otherwise approved by the City Engineer. Valves shall not be located in gutter flowlines, sidewalks, boulevards, travel route of a multiple use path, or within the wheel path of a vehicular travel lane. 3.2.4 Fire Flow. Fire flow requirements shall be determined by the Kalispell Fire Department. 3.2.5 Minimum Pipe Sizes. A. The minimum diameter of all mains shall be eight inches (8"). B. Fire hydrant leads may be permitted with six (6) inch diameter pipe. No hydrant leads may be longer than fifty (50) feet. 3.2.6 Pipe Material. Water main piping from six (6) to twelve (12) inches in diameter shall be Class 150 PVC pipe conforming to AWWA C-900 Standards. All water main piping larger than twelve (12) inches in diameter shall conform to AWWA C-905 Standards. 3.2.7 Water Service Lines. A. Structures containing two or more residences under separate ownership shall have separate service lines from the main, service valves and meters for each residence. B. Structures containing two or more residences, offices, or businesses that are rental units under common ownership shall have one service line, valve, and meter for all occupants within a single structure. C. When a lot or parcel is developed to a permitted use, all duplicate, excess, and/or unused water services and fire services, including stub -outs shall be abandoned at the main. D. Aggregation of parcels will trigger abandonment of unused water and fire services at the main. E. New or reconstructed services shall meet current City Standards, including location of curb stops and meter pits. F. Domestic water services shall not be tapped on a Fire Service Line or Fire Hydrant Main. 15 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.2.8 Gate Valves. Gate valves shall be Mueller Resilient Wedge Gate Valves, or an approved equal, conforming to AWWA C-509 Standards. All valves twelve (12) inches or smaller shall be gate valves. 3.2.9 Butterfly Valves. Butterfly valves shall be Mueller Lineseal Butterfly Valves, or an approved equal, conforming to AWWA C-504 Standards. All valves over twelve (12) inches in diameter shall be butterfly valves unless otherwise approved by the City Engineer. 3.2.10 Fire Hydrants. Fire hydrants shall be Red Mueller Super Centurion Fire Hydrants with 5" Storz adapter with cap conforming to AWWA C-502 Standards. The placement of all fire hydrants shall be subject to the approval of the Fire Chief. Hydrant spacing shall not exceed; 500 feet along streets in residential areas, 300 feet in commercial areas and 150 to 200 feet in industrial areas. Fire hydrants shall be installed a minimum of two (2) feet from the top back of curb to the barrel surface and a minimum of two (2) feet from the edge of sidewalk. Fire hydrants shall be covered until placed in service. 3.2.11 Service Saddles. Service saddles for PVC water mains shall be BR2 Series Mueller Brass (3/4" - 2"), or an approved equal, designed for use with AWWA C-900 PVC pipe. 3.2.12 Corporation Valves and Service Valves. Corporation valves and service valves shall be Mueller 300 Series ball valves, or an approved equal. 3.2.13 Service Fittings. Service fittings shall be Mueller Insta-Tite or 110 Series compression fittings, or an_approved equal. If larger than one (1) inch and smaller than four (4) inch, stainless steel inserts shall be used if recommended by manufacturer. 3.2.14 Curb Boxes. Curb boxes shall be Mueller H-10306 (3/4" or 1" service) or Mueller H-10310 (1 '/a", 1 '/z" or 2" service) cast iron extension type with arch pattern base, minimum length 6 1/2 feet, equipped with a properly sized stationary rod and a pentagon brass plug or approved equal. 3.2.15 Service Pipe. Service pipe up to three (3) inches in diameter shall be polyethylene pipe conforming to AWWA C-901 Standards. Service pipe four (4) inches or larger in diameter shall be Class 150 PVC pipe, conforming to AWWA C-900 Standards. 3.2.16 Meter Pits. A. Mueller Thermo -coil meter pits with center locking composite lids and insulation pads shall be used for new or reconstructed services up to 1" (Part No.: ###CS##72FS#LN) B. Mueller EZ Vault or approved equal with center locking composite lids and insulation pads shall be used for new services larger than 1 ". (Part No.: #4#VS##60FB#N) 3.2.17 Tapping Sleeves. Tapping sleeves shall be Romac SST III or an approved equal for service lines or main extensions larger than 4". Bolts for flange connection on tapping sleeves shall be Core -Ten or Core -Blue. It CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.2.18 Ductile Iron Fittings. Ductile iron fittings shall be Mechanical Joint Class 350 fittings conforming to AWWA C-153 Standards. 3.2.19 Valve Boxes. Main line valve boxes shall be designed for slip type adjustment. Valve boxes shall not be located in gutter flowlines or sidewalks. 3.2.20 Mechanical Joint Restraints. Megalug mechanical joint restraints, or approved equal may be used at all mechanical joint fittings. Thrust blocks shall be required at all mechanical joint fittings, whether restrained joint fittings are used or not. 3.2.21 Warning Tape. Detectable warning tape shall be a minimum of five (5) mils thick, three (3) inches wide and conform to APWA colors. Warning tape shall be buried twelve to twenty- four inches (12" — 24") below the final ground surface. 3.2.22 Toner Wire. All mains shall be laid with 14 gauge HDPE or HMWPE insulated solid core copper toner wire, approved by the manufacturer for direct bury. Toner wire shall be taped to the top of the water main. Splices of toner wire shall be made with moisture displacement connectors. Toner wire shall be brought to the surface at all valve boxes and shall be accessible at such boxes. 3.2.23 Marker Posts. Any water main, transmission main, or fire service line located outside of a paved surface shall be marked with Rhino Tri-view or approved equal marker posts at a minimum spacing of 150 feet, at every valve or valve cluster, and at every change in direction. Marker post color shall be APWA compliant. 3.3 SANITARY SEWER SYSTEMS. 3.3.1 Sanitary sewer systems shall be designed, constructed and tested in accordance with the current editions of Montana Department of Environmental Quality - Circular 2 Design Standards for Wastewater Facilities, Montana Public Works Standard Specifications and The Standards for Design and Construction, Kalispell, Montana. 3.3.2 Design Flows. Minimum design contributing wastewater flows shall be: 265 gallons per day per equivalent residential unit (ERU), with a peaking factor of 3.05, or design peak hour flow of 0.56 gallons per minute per ERU. (per March 2008 Wastewater Facility Plan, Chapter 1.5). 3.3.3 Design Report. The report for a project that will contribute inflow to an existing sewage lift station or a project that proposes a new lift station shall contain, but not be limited to, the following: A. A description of the existing and/or proposed wet well, pumping system and force main. B. The capacity of the existing and/or proposed pumps and potential for upgrading. C. A map showing the existing and/or proposed lift station service area. D. Existing lift stations shall include a list of the existing users and their average design flows. E. The existing and/or proposed peak design flow and reserve capacity. 17 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS F. The pump run and cycle times for the existing and/or proposed average and peak design flows. G. The hydraulic capacity of the existing and/or proposed force main. H. A list of the proposed users and their average design flows. I. The proposed average and peak design flows to the lift station. J. The reserve capacity of the lift station with the proposed project at full capacity. K. The pump run and cycle times for the proposed average and peak design flows. L. Recommendations for improvements to an existing lift station, if necessary to enable the lift station to serve the proposed project. 3.3.4 Sulfide Generation Analysis. The City Engineer may require sulfide generation analysis. If dissolved sulfide is likely to exceed 0.2 mg/L, non -corrosive linings may be required in addition to special lift station design. 3.3.5 Watertight Manhole Covers. Watertight manhole covers shall be required in all locations where flooding may occur. 3.3.6 Horizontal Location. Valves and manhole covers shall not be located in gutter flowlines, sidewalks, boulevards, or within the wheel path of a vehicular travel lane. 3.3.7 Gravity Sewers. Design Engineer shall submit a written report for all improvements or additions to the sanitary sewer system. The report shall assess the ability of the existing collection system to handle the peak design flow from the project and the impact on the Wastewater Treatment Plant. 3.3.8 Force Mains. Force mains shall be either DR11 HDPE or DR18 C900 PVC. No private sewer taps shall be made on City force mains. Private pressurized sewers shall be connected to the sewer collection system at a manhole as shown in Standard Detail SA.7. 3.3.9 Manholes. Manholes shall be provided at all active sanitary sewer main terminations or changes in direction. Stub -outs from manholes for future extension shall be capped at the termination and plugged inside the manhole with a mechanical plug. Inflatable plugs may not be used. Manholes shall have a minimum inside diameter of 4 feet. The invert of the outlet pipe shall be a minimum of 0.1 feet lower than the invert of the lowest inlet pipe for changes in direction less than 45°. The invert of the outlet pipe shall be a minimum of 0.2 feet lower than the invert of the lowest inlet pipe for changes in direction greater than 45°. 3.3.10 Manhole Joint Seals. Manholes shall be installed with nine (9) inch minimum width exterior rubberized joint seals. Joint seals shall be manufactured by one of the following: A. Infi-Shield Gator Wrap®; B. Press -Seal EZ-WRAP; C. Mar Mac® MacWrap; D. Riser-WrapTM; E. Con -Seal CS-212; or F. Equal product as approved by Public Works. 18 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.3.11 Manhole Chimney, Seals. Manholes shall be installed with one of the following acceptable chimney seals: A. Whirly Gig Manhole Riser Collar System; B. Cretex External Chimney Seal; C. Cretex Internal Chimney Seal; D. WrapidSealTM Manhole Encapsulation System; or E. Equal product as approved by Public Works. 3.3.12 Sewage Lift Station. A. Manufacturer. Unless otherwise approved by the City Engineer, new pumping systems shall be duplex, above ground, self -priming, suction lift type and the pumps shall be manufactured by the Gorman Rupp Company, or equal as approved by Public Works. Submersible 3" pumps or submersible grinder pumps will be considered based on the required operating volumes and heads of the proposed lift station. If a substitute manufacturer is requested, the Design Engineer shall provide all necessary information to justify the product as equal. In addition, the Design Engineer shall submit a list of three lift stations of the type proposed which have been in operation at least five years. The City reserves the right to accept or reject the proposed lift station. B. System shall be fully redundant with two (2) motor savers. C. Wiring inside lift station and lift station enclosure shall be water resistant. D. Backup Power. An emergency natural gas fueled generator shall be required for all lift stations. Generator shall be Generac or approved equal. Noise emissions from the power supply shall be limited to not more than 65 dbA at a distance of twenty (20) feet from the power supply. E. Influent Pipe. One joint of ductile iron pipe, Class 50 cement lined, shall be installed on the influent pipe to the wet well. The spigot end shall extend into the wet well 6" beyond the interior wall of the wet well. F. Access Road. The lift station shall be served by a 12-foot minimum width paved access way to provide access by sewer maintenance vehicles. The access way at the street shall have a concrete driveway between the curb and the sidewalk. 19 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS G. Enclosure. The above ground pumping system for the lift station shall be enclosed in a gable -roofed building. The building shall be constructed on a shallow monolithic concrete foundation with a 4-inch concrete floor slab. The treated sole plate shall be firmly anchored to the monolithic foundation. Roof trusses shall be spaced at twenty-four (24) inch maximum spacing and shall be designed to meet applicable local snow load requirements. Finished floor to ceiling shall be 8-feet. Roof slope shall be 4:12. The building shall be constructed with lap siding with a 7- inch reveal, '/2" OSB wall sheathing, 5/8" OSB roof sheathing, 30-year 3 tab shingles, 3068 steel door with deadbolt lock, 5/8" unfinished gypsum board ceiling, 6-inch wall studs, T-111 siding for interior wall covering, R-19 wall insulation, R- 49 ceiling insulation, and all other necessary materials for a finished building. Heating and air circulation system shall be provided. Interior lights shall be ceiling mounted industrial lights in protective cages. The structural, mechanical, heating, electrical, and air circulation plans shall be submitted by the project engineer for review by the Public Works Department. H. Alarm. An alarm system shall be provided that is capable of detecting power interruption, high water and high motor temperature conditions. The alarm signals shall be directed to an onsite alarm monitoring and telephone dialer system. The alarm monitoring and telephone dialing system shall be manufactured by Mission Communications. I. Model M-110 shall be provided and installed for lift stations with pump motors under 20 horsepower. lI. Model M-800 shall be provided and installed for lift stations with pump motors 20 horsepower and greater. M-800 units shall include a Digital Expansion Board to add 8 digital inputs and an Analog Expansion Board to add 4 analog inputs. Controls. An hour meter, suction pressure gauge tap and valve, and discharge pressure gauge tap and valve, are required on each pump. Amperage meters are required on each leg of the electrical wiring. Controls shall include a pump run alternator. The electrical power supply shall contain lightning protection. The primary level control system shall be a transducer. The backup level control system shall be encapsulated mercury float switches. J. Fencing. All lift station facilities shall include a six (6) foot chain link security fence with three (3) foot wide personnel gate and a twelve (12) foot wide gate with two six (6) foot leaves. Perimeter fencing shall provide adequate room for facility access and maintenance and shall provide a minimum offset of three (3) feet to all lift station structures or appurtenances. Gate(s) shall be located to promote maintenance vehicle access for pump removal. Gate installations shall include duckbill style gate holdbacks. K. Lighting. Exterior yard lighting shall be provided and connected to power supply. Street lighting shall not be considered adequate to meet this requirement. 20 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS L. Bypass. Valving and connections shall be provided so that in the event of both pumps failing, an emergency pump can be connected to the force main. Provide a three (3) inch cam -lock style quick connection with cap. Bypass must have appropriately sized dedicated valve and connect downstream of the lift station check valve(s). M. Landscaping. Landscaping shall consist of four (4) inches of clean one (1) inch minus gravel or other landscaping rock as approved by Public Works. 3.3.13 Minimum Pipe Size. The minimum diameter of any gravity sanitary sewer main shall be eight (8) inches. Mains shall only be upsized to meet capacity needs. Upsizing of mains will not be approved for utilization of minimum slopes to meet elevation restraints. 3.3.14 Minimum Depth. The depths of sewers shall be in accordance with MDEQ Circular 2. 3.3.15 Sanitary Sewer Service Lines. A. Structures containing two or more residences under separate ownership, such as townhouses, shall have separate sewer service lines for each residence. B. Structures containing two or more residences, offices or business that are rental units under common ownership shall have one service line for all occupants within a single structure. C. The terminal end of sanitary sewer services at undeveloped lots shall be marked with a steel T-Post buried to within 6" of the surface. D. When a lot or parcel is developed to a permitted use, duplicate and/or unused sewer services, including stub -outs shall be abandoned at the main. E. Aggregation of parcels will trigger abandonment of unused sewer services at the main. F. New or reconstructed services shall meet current City Standards. G. Sewer service taps shall only be made at the main. 3.3.16 Quality of Sewage. No development shall introduce any sewage into the City of Kalispell Sanitary Sewer System that is not consistent with the requirements of Ordinance 854, or as subsequently amended. No storm water, surface water, or groundwater shall discharge to any sanitary sewer. All services will be required to adhere to the pretreatment and surcharge ordinance. 3.3.17 Sanitary Sewer Manhole Ring and Cover. The sanitary sewer manhole ring and cover shall be as shown in Detail SA.8 or approved equal. Paint by manufacturer is optional. 3.3.18 Warning Tape for Force Mains. Detectable warning tape shall be a minimum of five (5) mils thick, three (3) inches wide and conform to APWA colors. Warning tape shall be buried twelve to twenty-four (12-24) inches below finished ground surface. 21 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.3.19 Toner Wire for Force Mains. All force mains shall be laid with 14 gauge HDPE or HMWPE insulated solid core copper toner wire, approved by the manufacturer for direct bury. Toner wire shall be taped to the top of the force main. Splices of toner wire shall be made with moisture displacement connectors. All force mains burst through existing mains or installed without continuous trench access shall be installed with'/4" steel toner cable. 3.3.20 Marker Posts. Any sewer main, force main, or interceptor located outside of a paved surface shall be marked with Rhino Tri-view or approved equal marker posts at a minimum spacing of 150 feet, at every valve or valve cluster, at every manhole and at every change in direction. Marker post color shall be APWA compliant. 3.3.21 Oil/Water Separators. A. All services will be required to adhere to the pretreatment and surcharge ordinance. B. Automotive repair facilities and paint shops, dealerships, gas stations, equipment degreasing areas, and other facilities generating wastewater with oil and grease content are required to pretreat these wastes before discharging to the City sanitary sewer system. Pretreatment requires that an oil/water separator be installed and maintained on site. C. Oil/water separators for commercial/industrial processes must be sized on a case - by -case analysis of wastewater characteristics. Typically a minimum capacity of 750 gallons is required for small gas stations, auto repairs, and light commercial sites; 1,500-gallon capacity for large-scale truck washing and steam cleaning facilities. The ultimate discharge must be directed to the sanitary sewer system. All units regardless of size shall be fitted with a standard final -stage sample box and spill -absorbent pillows. D. Oil/water separators shall be commercially manufactured and sized for the intended discharge rates for the facility where it is to be installed. 3.3.22 Sample Ports. Approved sewer sample ports shall be provided on sewer services downstream of any grease trap, oil/water separator, sewage pretreatment structure, or as otherwise required according to the Kalispell Pretreatment program,. 3.4 ROADWAYS AND WALKWAYS 3.4.1 Roadway systems including private roadways shall be designed, signed and constructed in accordance with the current edition of the Standards for Design and Construction for the City of Kalispell, Montana, the Montana Public Works Standard Specifications, the current Manual on Uniform Traffic Control Devices, and The Subdivision Regulations of the City of Kalispell. All roads within a proposed subdivision shall be designed by a professional engineer and approved by the City Engineer. Upon completion of roadway construction, a professional engineer shall certify that the construction meets the requirements of the Standards for Design and Construction, Kalispell, Montana. ox CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.4.2 Asphalt Surface. Pavement and material testing requirements shall be in accordance with MPWSS Section 02510 Paragraph 3.29, except: A. Subsection E shall be replaced with: "The field density and thickness of the pavement is determined by measuring the cores tested. The actual thickness shall not be less than the design thickness, and shall in no case be less than four (4) inches." B. Subsection F shall be replaced with: "Asphalt compaction samples will be taken according to AASHTO T 230 and tested in accordance with AASHTO T 166. One location per lane per block as determined by the Engineer shall be required. Asphalt compactions identified to be less than specified shall be subject to rejection for the lane and block from which the specimen was taken as determined by the Engineer. C. Add subsection G to the standard as follows: "Asphalt thickness shall be measured using full depth core samples. Thickness shall be measured from the surface of the specimen to the bottom of the uniform plant mix which thickness shall not include foreign materials, seal coat, foundation material, soil, paper or foil. Thickness less than specified thickness as measured on the acceptance sample shall be subject to rejection for the lane and block from which the specimen was taken as determined by the Engineer." 3.4.3 Traffic Analysis. A. Developments contributing three hundred (300) or more vehicle trips per day to the City street system shall require a traffic impact analysis. A registered engineer with a Professional Traffic Operation Engineer (PTOE) certification shall submit to the City a traffic impact analysis report. This report shall state the existing traffic conditions for all impacted roadways, including the existing levels of service for each road. B. The report shall identify all negative impacts associated with the proposed development and shall thoroughly detail a mitigation plan for the negative impacts of the proposed development. The developer shall be responsible to maintain the level of service of the affected existing roadway system. The report shall also take into consideration other forms of transportation including bicycle and pedestrian. C. The Traffic Impact Study shall be completed in accordance with Montana Department of Transportation requirements and nationally accepted standards. The Traffic Impact Study will assess anticipated traffic impacts associated with the proposed development and recommend appropriate mitigation measures for the adjacent transportation network. D. Recommendations developed will be based upon nationally accepted traffic engineering principles, and related resources. 23 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.4.4 Street Intersections: A. All intersections shall be designed in accordance with the most recent version of AASHTO's A POLICY ON GEOMETRIC DESIGN OF HIGHWAYS AND STREETS. No trees, fences, or other sight obstructions may be constructed within intersection departure sight triangles as required by City Zoning Ordinance. B. Streets shall intersect at 90' angles, if topography permits, but in no case shall the angle of intersection be less than 75' for a minimum distance of 60 feet as measured along the centerline, from the right-of-way line at the intersecting street. C. No more than two streets may intersect at one point. D. Two streets meeting a third street from opposite sides shall meet the same point, or their centerlines shall be offset at least 125 feet for local roads and 300 feet for collectors. E. Intersections of local streets with major arterials shall be kept to a minimum. F. Maximum straight tangent grade of approach to any intersection shall not exceed 2% for a distance of 60 feet as measured from edge of transverse pavement to provide for adequate starting, stopping and stacking distances. G. The minimum back of the curb radii at street intersection shall meet requirements shown in standard drawings for street classification. 3.4.5 Cul-De-Sacs. All dead-end streets shall terminate in an approved cul-de-sac. Where future street extension is proposed, a temporary cul-de-sac of adequate size as approved by the Fire Chief and City Engineer shall be provided. Unless otherwise approved by the City Engineer, roadways that terminate at a cul-de-sac shall have a maximum length of six hundred (600) feet. The cul-de-sac radius shall be forty seven feet (47') to the back of the curb and fifty eight feet (58') to the right-of-way. A six foot (6') boulevard and a five foot (5') sidewalk is required. A. Horizontal and Vertical Alignment. Horizontal and vertical alignment of streets must ensure adequate sight distances. A minimum sight distance of 200 feet shall be required in all vertical and horizontal curves. Collector street alignment shall be designed for a design speed of 35 miles per hour in accordance with the latest adopted edition of AASHTO A POLICY ON GEOMETRIC DESIGN OF HIGHWAYS AND STREETS. 3.4.6 Collector and Arterial Streets. Location of collector and arterial streets shall comply with the Kalispell Growth Policy, current Area Transportation Plan, or any other major street and highway plan as adopted by the Flathead County Board of County Commissioners and/or the City of Kalispell. The development of frontage roads or shared accesses serving new developments shall be used along collectors and arterials rather than the use of individual driveways or approaches. 24 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.4.7 Street Sub base. The sub base for streets shall be crushed stone in accordance with Montana Public Works Standard Specifications Section 02234 and may include up to 3" minus material with at least one fractured face. Larger material may be approved on a case by case basis, with at least one fractured face. 3.4.8 Traffic Control Signs, Street Name Signs and Street Names. A. General I. The developer shall provide and install necessary Traffic Control Signs in accordance with the Manual on Uniform Traffic Control Devices. II. Road Name Signs shall be installed at each intersection. III. New roads shall be assigned a road name when roads exceed 300 feet in length, or serve three (3) or more properties. Alleys shall not be considered roads for consideration of road names. IV. All proposed road names shall be submitted to the Public Works for approval prior to preliminary plat submittal. V. A road naming assignment by the City to any road shall not constitute or imply jurisdiction, ownership, right of use, guarantee of access, or acceptance into the City road maintenance program. Private roads shall be designated by a PVT suffix to the road name. B. Road Geometric Guidelines I. A road shall be essentially continuous, without gaps. II. If a road has a branch or branches, separate names shall be used for the minor branch(es). III. Each road shall have the same name throughout its entire length, except that a road name may change when, and only when, there is a substantial intersection or at municipal boundaries. C. Road Name Guidelines I. A proposed new road name which duplicates an existing or reserved road name (singular or plural form) in the City of Kalispell or Flathead County shall not be approved. II. Road names are limited to three (3) words not including the road name suffix. III. A road name shall not exceed more than twenty (20) characters including spaces and the road name suffix abbreviation. IV. A new road name shall not include numeric numbers, dashes, apostrophes, or other non -alphabetic characters. V. Because North, South, East and West are directional features of the addressing system and lead to confusing addresses if included as part of the name, cardinal directions shall not be part of any road name (e.g. Westview Road or Southpoint Dr. shall not be acceptable as new road names). VI. Articles (the, a, an) shall not be used to begin road names. VII. Road names cannot contain initials, abbreviations, or single -letters. 25 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS VIII. No road name shall be approved which begins with a word that appears as the first word in five or more official road names. IX. Road names shall not include obscene, racial, or derogatory terms. X. The primary name portion of a road shall not be abbreviated (e.g. Mount Charles Dr. not Mt. Charles Dr.) XI. Where a proposed road is a continuation of, or in alignment with, an approved road, it shall utilize the same road name as the approved road. A new road name shall be required if the proposed road is disconnected from the centerline of the existing road by n offset greater than sixty (60) feet. XII. Road names should be consistent and singular for any particular road. The road name adopted by the City of Kalispell for roads within its jurisdiction shall be the officially recognized road name. XIII. The use of road name suffixes shall be consistent with the Flathead County Road Naming and Site Addressing Resolution. 3.4.9 Sidewalks. All developments shall have sidewalks which will allow pedestrians to safely travel from any part of the development to the boundaries of the development. Developments abutting existing or proposed roadways will be required to have sidewalks within the public right-of-way and parallel to the roadways. The minimum width of a sidewalk shall be five (5) feet. Sidewalks are required on both sides of the street in all subdivisions. Sidewalks shall be separated from the street by a six (6) foot wide boulevard for collectors or nine (9) foot wide boulevard for local streets. 3.4.10 Boulevard/Open Space. Boulevard/open space shall be landscaped in accordance with the Kalispell Street Tree Ordinance with a plan approved by the Kalispell Parks and Recreation Department. Table 1 - Road DesiLrn Standards for Local Subdivision Streets DESIGN STANDARDS ARTERIAL COLLECTOR LOCAL Right -of -Way 80 ft 60 ft. 60 ft Pavement Width As approved by City Engineer 34 ft. 28 ft. Maximum Grade 8% 8% 8% Cul-de-sac turnaround. a. Back of curb radius 47 ft b. Minimum right-of-way radius 58 ft c. Maximum length 600 ft l On street parking governed by City of Kalispell Subdivision Regulations. 2 Measured from the centerline of the intersection to the center point of the cul-de-sac. 26 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.5 DRIVEWAYS 3.5.1 The nearest edge of any residential driveway shall be not less than thirty five (35) feet from the edge of the pavement to the nearest intersecting street. All new driveway locations and modifications to existing driveways shall be reviewed and approved by the Public Works Department (Application for Driveway Construction) prior to beginning construction. 3.5.2 All driveways shall be constructed per standard drawing ST.10 or ST.11. 3.6 PLACEMENT OF UTILITIES 3.6.1 See Section 3.1.7D. 3.6.2 All applicable laws, rules and regulations of appropriate regulatory authority having jurisdiction over utilities shall be observed. 3.7 STREET LIGHTING 3.7.1 Purpose. A. Provide consistent and reliable lighting in outdoor public places where public health, safety and welfare are concerns. B. Provide lighting for vehicular traffic, pedestrian, and bicycle travel. 3.7.2 General A. All new streets and subdivisions shall adhere to these standards. All street lighting shall be designed to Flathead Electric Cooperative's (FEC) standards (See Table 2), unless the light assemblies are owned and maintained by an entity other than the City of Kalispell, (See Table 3). B. All light fixtures shall be full cut off as defined by the Illuminating Engineering Society of North America (IES). C. All lighting layouts must be approved by the Public Works Department. D. Light fixtures are required at all intersections, mailbox groups, and pedestrian bus stop locations. 3.7.3 Lighting A. Intersections I. All streets shall have lighting on at least one corner of the intersection. If the street is four or more total lanes, two lights are required at diagonally opposite corners, or sufficient fixtures to provide minimum foot candle levels. B. Streets 1. Street lights shall be in accordance with the following tables and text. 27 CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS Table 2 - FEC's Standards Classification Fixture Type and pole Lamp wattage and Type Spacing Local FEC's standard full cut-off cobra head w/Type Commercial[" III distribution on a 30 foot pole, mounted to FEC 200W HPS 200 ft Standard concrete pole bases. Local FEC's standard full cut-off cobra head w/Type Residential III distribution on a 30 foot pole, mounted to FEC 100W HPS 250 ft Standard concrete pole bases. II. All streets shall be illuminated from both sides of the street. a. When streets contain less than four total lanes, lights on one side shall be offset from the other side by the spacing criteria. b. When streets have four or more total lanes, lights on one side shall be offset from the other side by half the spacing criteria. III. Light placement can vary from table spacing by a maximum of 15% with approval from the Public Works Department. IV. If the road has sharp bends, lighting design must meet the average illuminance and illuminance uniformity criteria established in Table 3. V. For street lighting applications that do not conform to FEC's cobra head style standards, i.e., developer owned decorative fixtures in a subdivision; a sidewalk photometric plan must be submitted with light placement that meets the criteria shown in Table 3. Table 3 - Owner Metered/Maintained Average Illuminance Pole Max lam Classification Illuminance'�1 Uniformity"' Height (foot candles) Ave/Min (ft) wattage/type Local Commercial 0.6 6/1 20-30 200W / HPS Local Residential 0.3 6/1 15-30 IOOW / HPS VI. Exceptions allowed if approved by the Public Works Department. C. Pedestrian Gathering Areas At all mailbox groups, bus stops, and pedestrian pathway intersections with streets, a light fixture is required to indicate the location of this area. 1 Commercial as designated by the City of Kalispell. 2 Value to be measured on the sidewalk. I: CHAPTER 3 — WATER/SEWER/STREET DESIGN STANDARDS 3.7.4 Submittals A. Street lighting plans shall be submitted to the Public Works Department for approval at the same time as the street plans. B. For all designs, submit design layout for placement of light fixtures. C. For designs following the criteria established in Table 3, provide the following for approval: I. Photometric plan with isoilluminance lines indicating appropriate foot candle levels. II. On photometric plans, provide a table indicating average foot candles, ave/min ratios, and max to min ratios for roadways, sidewalks, and pedestrian intersections. 3.8 UTILITY EASEMENTS. 3.8.1 All public utility easements shall be fifteen (15) feet wide for a single pipeline, with the pipe centerline five (5) feet from one easement edge. For easements with two pipelines, the minimum width shall be twenty (20) feet with each pipe centerline five (5) feet from the easement edge. 3.9 MULTIPLE USE PATHS 3.9.1 Non -motorized use paths shall be designed in accordance with the most recent version of AASHTO's "Guide for the Development of Bicycle Facilities" and "Guide for the Planning, Design and Operation of Pedestrian Facilities". Paths shall be a minimum of ten feet (10') wide. In limited instances, the Public Works Director may require the path to be built to accommodate HS-20 loading if the path serves as an emergency or maintenance access route. 3.9.2 No catch basins, valve boxes, curb boxes, or other utility appurtenances shall be located within the travel route of a path. Path signage shall conform to the most current Manual on Uniform Traffic Control Devices (MUTCD). In subdivisions, required paths shall be located within common areas owned and maintained by the property owners' association. 3.9.3 The surfacing section required on paths is three (3) inches of asphalt on eight (8) inches of 3/4 inch minus crushed base compacted to 95% max dry density. Landings and ramps shall be constructed of concrete meeting sidewalk standards. 29 CHAPTER 4 — STORMWATER DESIGN SECTION 4.1.1 A Chapter 4 - Stormwater Design 4.1 INTRODUCTION 4.1.1 OBJECTIVE AND PURPOSE A. Development projects in urban areas generally result in the replacement of open land with impervious surfaces that prevent infiltration and increase stormwater runoff rate and volume. This changes the patterns of stormwater runoff, which can lead to flooding problems —at the project site and on properties downstream —and can affect water quality, as sediment and pollutants are transported into streams, wetlands, lakes and groundwater. B. The purpose of Chapter 4 - Stormwater Design is to protect water quality, prevent adverse impacts from flooding, and control stormwater runoff to levels equivalent to pre -development. 4.1.2 USING THE STORMWATER CHAPTER A. This chapter provides engineers, developers, and the general public with procedures and assistance for designing stormwater management facilities associated with land development, road and drainage projects. It outlines minimum requirements for the design of stormwater management systems. B. This chapter references and refers information from the following City of Kalispell Document (available from the Public Works Department): I. City of Kalispell 2008 Storm Water Facility Plan Update; and, IL City of Kalispell Stormwater Quality Management Plan. 4.1.3 GENERAL REQUIREMENTS A. The owner or owner's agent is responsible for the following: I. Coordinating project consultants; II. Providing complete drainage submittals; III. Ensuring adherence to: a. The standards and criteria presented in this manual; b. The Conditions of Approval, if applicable; C. Any conditions established by the City Engineer; d. General project management; and, e. Permits required by the City of Kalispell or other agencies. 30 CHAPTER 4 — STORMWATER DESIGN SECTION 4.1.313 B. The owner or owner's agent is required to obtain approval of the drainage submittal from the Public Works Department prior to any of the following: I. Major and minor subdivision final plat approval; II. Site plan approval; III. Issuance of a Building Permit; and, IV. Issuance of a City Excavation Permit (for work in City Right -of Way). C. The drainage submittal shall be prepared in accordance with this manual. The submittal shall be prepared by a professional engineer currently licensed in the State of Montana and shall be submitted to the Public Works Department for review and acceptance. D. The rate and volume of stormwater runoff originating on any proposed land development, road or area draining to, across or through the project site shall be estimated in accordance with the criteria presented in this manual. These estimates shall be the basis of the drainage report. The peak rate of stormwater runoff from any proposed land development to any natural or constructed point of discharge downstream shall not exceed the pre -development peak rate of runoff. The post development volume of runoff can exceed the pre -development volume of runoff when the required down -gradient analysis demonstrates that there will be no adverse impacts on down gradient properties or existing natural and constructed conveyance systems. Adverse impacts include, but are not limited to: additional ponding of water on downstream properties, erosion or sedimentation, property damage, increased downstream ponding residence times, etc. E. Stormwater runoff from a developed site shall leave the site in the same manner and location as it did in the pre -developed condition. Flow may not be concentrated onto down -gradient properties where sheet flow previously existed. Drainage shall not be diverted and released downstream at points not receiving drainage prior to the proposed development. A down -gradient analysis demonstrating that there will be no expected adverse impacts on down gradient properties will be required. 31 CHAPTER 4 — STORMWATER DESIGN SECTION 4.1.4A 4.1.4 STANDARD OF CARE A. The standards presented in this manual should be considered the minimum requirements to be used in the design of stormwater facilities. Due to special site conditions, environmental constraints, or other applicable laws, stormwater management designs may frequently need to exceed the minimum requirements. It is incumbent upon the engineer to use good engineering practice and to be aware of, and implement new design practices and procedures that reflect current techniques in stormwater design, providing sufficient measures to ensure that the drainage facilities function as intended. Good engineering practice is defined in these standards as professional and ethical conduct that meets the current codes and regulations adopted for engineers. The proposed design shall consider functionality, constructability and maintenance, including the health, safety and welfare of the public. 4.1.5 SEVERABILITY A. If any section, sentence, clause or phrase of this manual should be held invalid or unconstitutional, the validity or constitutionality thereof shall not affect the validity or constitutionality of any other section, sentence, clause or phrase of this manual. 4.2 BASIC REQUIREMENTS 4.2.1 INTRODUCTION A. This section introduces the seven Basic Requirements for new development and redevelopment projects in the City of Kalispell: I. Basic Requirement No. 1 — Drainage Submittal; II. Basic Requirement No. 2 — Geotechnical Site Characterization; III. Basic Requirement No. 3 — Water Quality Treatment; IV. Basic Requirement No. 4 — Flow Control; V. Basic Requirement No. 5 — Natural and Constructed Conveyance Systems; VI. Basic Requirement No. 6 — Erosion and Sediment Control; and, VII. Basic Requirement No. 7 — Operation and Maintenance. B. The applicability of these requirements depends on the type, size, and location of the project. It is the responsibility of the project owner or owner's agent to become familiar with the Basic Requirements in order to determine when they are applicable. C. REGULATORY THRESHOLD I. The regulatory threshold is the "trigger" for requiring compliance with the Basic Requirements of this manual. In the City of Kalispell, it is defined as "the addition or replacement of 10,000 square feet or more of impervious surfaces at full development. 32 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.1 D D. NEW DEVELOPMENT I. New development is the conversion of previously undeveloped or permeable surfaces to impervious surfaces and managed landscape areas. New development occurs on vacant land or through expansion of partially developed sites. II. All new development projects, regardless of whether the project meets the regulatory threshold, shall comply with Basic Requirements 5, and 6. IIl. All new development projects that meet the regulatory threshold shall comply with ALL Basic Requirements (1 through 7) IV. The City Engineer reserves the right to require compliance with any or all of the Basic Requirements regardless of the size of the project or the amount of impervious area added or replaced. E. REDEVELOPMENT I. Redevelopment is the replacement of impervious surfaces on a developed site. Redevelopment occurs when existing facilities are demolished and rebuilt or substantially improved through reconstruction. Rebuilt or reconstructed facilities are regarded in the same manner as new development and shall comply with the Basic Requirements of this manual. II. On redeveloped sites where pre-existing facilities remain, the old facilities are not subject to the requirements of this manual if they remain hydraulically isolated from the new facilities. For projects that are implemented in incremental stages, the redevelopment threshold applies to the total amount of impervious surface replaced at full build -out; the new development thresholds apply to the total amount of new impervious surfaces added at full build -out. III. The long-term goal of the redevelopment standard is to reduce stormwater pollution from existing developed sites, especially when a water quality problem has been identified or the site is being improved to accommodate a use with a greater potential to contribute pollution to the receiving waters. IV. A project may be granted a design deviation when site conditions prevent full compliance with the Basic Requirements; however, every effort shall be made to find creative ways to meet the intent of the Basic Requirements. Design deviations will not be granted waiving stormwater requirements for new impervious surfaces. V. Sites with 100% existing building coverage that are currently connected to a municipally owned storm sewer or discharge to water of the state must be evaluated on a case -by case basis to continue to be connected without treatment; additional requirements such as flow restrictors may also be required. 33 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.1F F. EXEMPTIONS 1. Projects are exempt from the Basic Requirements when falling under any of the following categories: a. Actions by a public utility or any other governmental agency to remove or alleviate an emergency condition, restore utility service, or reopen a public thoroughfare to traffic; b. Records of survey, boundary, i.e., minor lot line adjustments, and property aggregations, unless the action affects drainage tracts or easements; C. City right-of-way maintenance and reconstruction projects. d. Projects that, when completed, will not have physically disturbed the land; e. City right-of-way parking area preservation and maintenance projects such as: i Pothole and square cut patching; ii Crack sealing; iii Shoulder grading; and iv Vegetation maintenance. G. DESIGN DEVIATION I. A design deviation is an administrative approval of design elements that do not conform to or are not explicitly addressed by this manual. II. The requirements of this manual represent the minimum criteria for the design of stormwater management systems. Designs that offer a superior alternative to standard measures, or creative means not yet specified in the standards, are encouraged. II1. Applicability a. The project owner or owner's agent shall request a design deviation when proposing non-standard methods, analysis, design elements or materials. A design deviation will only be considered for review if: i The design elements proposed do not conflict with or modify a condition of approval; and, ii The design elements proposed are based on sound engineering principles and best management practices, and are not inconsistent with the public interest in stormwater control and environmental protection. 34 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.2A IV. Submittal a. For consideration of a design deviation, the project owner or owner's agent shall submit a design deviation request and supporting documentation. The supporting documentation shall include sufficient information to make a decision as to the adequacy of the proposed facility or design. If infiltration is proposed, negative impacts on down -gradient properties are of concern, or seasonal high groundwater is suspected, then a geotechnical site characterization shall be submitted as part of the design deviation package. The design deviation package shall demonstrate that: i There are special physical circumstances or conditions affecting the property that may prohibit the application of some of the Basic Requirements in this Manual; ii Every effort has been made to find alternative ways to meet the objectives of the Basic Requirements; iii Approving the design deviation will not cause adverse impact on down -gradient properties, public health or welfare; and, iv Approving the design deviation will not adversely affect the recommendations of any applicable comprehensive drainage plan. 4.2.2 BASIC REQUIREMENTS A. BASIC REQUIREMENT NO. 1 — DRAINAGE SUBMITTAL I. Projects are expected to demonstrate compliance with all applicable Basic Requirements through the preparation of a Drainage Submittal. The Drainage Submittal shall include road and drainage construction plans, a drainage report that describes the proposed measures to dispose of stormwater, and other supporting documentation as needed. The contents of the Drainage Submittal will vary with the type, size, location of the project, and individual site characteristics. II. The City Public Works Department reviews the Drainage Submittal for compliance with this manual and other applicable standards. Specific requirements for the Drainage Submittal are discussed in Section 4.3. III. Applicability a. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in 4.2.1C. A Drainage Submittal is generally required for any land -disturbing activity. Land -disturbing activities are those that result in a change in the existing soil cover (both vegetative and non - vegetative) or site topography. The sections below summarize the types of activities that require a Drainage Submittal, as well as those that are exempt. 35 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.2A b. A drainage submittal is required for the following types of activities: i Commercial and industrial buildings including institutional and multi -family residential projects; ii Minor or major subdivisions; iii Change of use; iv Conditional use permits; v Plan Unit Developments (PUD) vi Public or private parking lots; and, vii Public or private road projects. C. The following types of activities are generally exempt from the requirement to prepare a drainage submittal: i Single-family residential/duplex building permits; ii Temporary use permits, unless the use could cause adverse water quality impacts or other drainage -related impacts; iii Land -disturbing activities that do not require a City Stormwater Management Permit for construction sites, unless the activity could cause adverse water quality impacts or other drainage -related impacts; iv Maintenance projects that do not increase the traffic -carrying capacity of a roadway or parking area within the right-of-way, such as: A) Removing and replacing a concrete or asphalt roadway to base course or subgrade or lower without expanding or improving the impervious surfaces; B) Repairing a roadway base or subgrade; C) Resurfacing with in -kind material without expanding the area of coverage; D) Overlaying existing asphalt or concrete pavement with asphalt or concrete without expanding the area of coverage; and, E) Chip seal projects. d. The following types of activities are exempt from the requirement to prepare a drainage submittal: Actions by a public utility or any other governmental agency to remove or alleviate an emergency condition, restore utility service, or reopen a public thoroughfare to traffic; ii City construction or maintenance projects; iii Records of survey, boundary line adjustments, and property aggregations, unless the action affects drainage tracts and easements; iv Operation and maintenance or repair of existing facilities; and, 36 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.213 v City street and City parking area preservation/maintenance projects within the right-of-way, such as: A) Pothole and square -cut patching; B) Crack sealing; C) Shoulder grading; or, D) Vegetation maintenance. B. BASIC REQUIREMENT NO. 2 — GEOTECHNICAL SITE CHARACTERIZATION I. A geotechnical site characterization (GSC) is required to demonstrate suitability for stormwater disposal and to determine sub -level structure construction feasibility. A professional engineer currently licensed in the State of Montana is required to perform the GSC. Hydrogeologists and engineering geologists may prepare geotechnical site characterization studies, excluding structural, foundation and pavement design. The study shall be performed in accordance with the criteria specified in Section 4.4. II. Applicability a. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2.1. A GSC will be required for most projects. The scope and geographic extent of the investigation may vary depending on the general location and setting of the site, the characteristics of the target soil deposits, and whether there are known or anticipated drainage problems in the vicinity of the site. b. A GSC is required for: i Projects proposing infiltration (infiltration facilities, detention facilities receiving credit for pond bottom infiltration, etc.); ii Projects located within or draining to a problem drainage area or study area as recognized by the City Engineer; or, iii Projects with proposed sub -level structures (building foundations, City utilities, etc. or as required by the City Engineer). iv Identified areas of the City with high ground water. C. BASIC REQUIREMENT NO. 3 — WATER QUALITY TREATMENT Water quality treatment is required to reduce pollutant loads and concentrations in stormwater. The BMPs described in Section 4.6 are designed to reduce or eliminate certain pollutants. When required, treatment facilities shall be designed according to the criteria specified below, in Section 4.6, and in the Stormwater Quality Management Plan. The Stormwater Quality Management Plan can be obtained from the Kalispell Public Works Department. 37 C1 APTER 4 — STORMWATER DESIGN SECTION 4.2.21) II. Applicability a. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2.1. Water quality treatment is recommended but not required when the project is a part of a larger development which already addresses water quality treatment. The Stormwater Quality Management Plan outlines specific requirement for water quality treatment in the City of Kalispell. b. The project sites with water quality treatment exemptions are superseded by requirements set forth in any applicable Total Maximum Daily Load (TMDL) or other water cleanup plan. At the time of the writing of this manual, no TMDLs exist for water bodies in the City of Kalispell. Contact the City Engineer for current information on whether any TMDLs have been issued. III. Design Criteria a. Stream and River Flow Control Standard: The post development 10-year peak runoff rate shall be no greater than the pre -development 10-year, 24-hour peak runoff rate (based on SCS Type 1 unit hydrograph). b. Wetland Standards i An onsite wetland analysis is required for all new development. See Wetland Analysis in Section 4.3.3 Drainage Report; and, ii Flow control: See Wetland Flow Control Standards Chapter 6, in the Stormwater Quality Management Plan. C. Water Quality Volume Standard The water quality volume for the design of BMPs is based on the design volume of runoff from the first 0.5 inch of rainfall from a 24 hour storm. Refer to Section 4.6 for more details. D. BASIC REQUIREMENT NO. 4 — FLOW CONTROL I. Flow control facilities are necessary to protect stream morphology and habitat and to mitigate potential adverse impacts on down -gradient properties and floodplains due to the increase in stormwater runoff caused by land development. II. The peak rate of stormwater runoff from any proposed land development to any natural or constructed point of discharge downstream shall not exceed the pre - development peak rate of runoff. The post development volume of runoff can exceed the pre -development volume of runoff when the required down -gradient analysis demonstrates that there will be no adverse impacts on down gradient properties or existing natural and constructed conveyance systems. The City Engineer reserves the right to deny a request for increased stormwater volumes or to condition any approval at their sole discretion. 38 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.2D III. When site conditions allow, infiltration is the preferred method of flow control for urban runoff. All projects are encouraged to infiltrate stormwater runoff on site to the greatest extent possible if such infiltration will not have adverse impacts on down- gradient properties or improvements. Flow control facilities shall be designed and constructed according to the criteria in Sections 4.5, 4.6, and 4.7. IV. Applicability a. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2.1. All projects that meet the regulatory threshold shall comply with this Basic Requirement. V. Design Criteria a. All Facilities: i The NRCS Type I 24-hour storm event is the design storm for all flow control facilities that use a surface discharge or a combined surface and subsurface system. The design water surface for all facilities shall be the 100-year post developed water surface elevation. All overflows (structure or spillway) shall be located above the design water surface elevation and pass the 100-year 24-hr developed peak flow rate. ii The total post -developed discharge rate leaving the site shall be limited to the pre -development rates listed in Table 4. Bypass flow shall be discharged at the pre -developed flow rate. Bypass flow is the runoff that leaves the site without being conveyed through the new development or redevelopment drainage system. b. Infiltration Facilities: Infiltration facilities shall be sized to fully infiltrate the post -development NRCS Type 1 10-year 24-hr design storm and the design water surface for all facilities shall be the 100-year post developed water surface elevation. All overflows (structure or spillway) shall pass the 100-year 24-hr developed peak flow rate. The overflow path shall drain toward the natural discharge point of the contributing basin, such that the overflow route or termination of stormwater does not adversely impact down - gradient properties or structures. C. Retention Facilities: For projects proposing Retention, the facilities shall be designed to store the 100-year 24-hr post development storm events and shall provide an overflow path, wherever possible, with the capacity to convey the 100-year storm event. d. Detention Facilities: For projects proposing to detain and release stormwater runoff, the facilities shall be designed such that the release rate does not exceed the pre -developed conditions for a range of storm events. The analysis of multiple design storms is needed to control and attenuate both low and high flow storm events. 39 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.2E Table 4 - Allowable Discharge Rates Design Frequency Post -Developed Discharge Rateltl (24-hour storm) 10-year <10-year 24-hr pre -developed 100-year <100-year 24-hr pre -developed 100-year (Emergency Overflow) > 100-year 24-hr post -developed - Overflow route only l21 E. BASIC REQUIREMENT NO. 5 — NATURAL AND CONSTRUCTED CONVEYANCE SYSTEMS I. A conveyance system includes all natural or constructed components that collect stormwater runoff and convey it away from structures in a manner that adequately drains sites and roadways, minimizing the potential for flooding and erosion. Il. Engineered conveyance elements for proposed projects shall be analyzed, designed, and constructed to provide protection against damage to property and improvements from uncontrolled or diverted flows, flooding and erosion. III. Projects shall be designed to protect certain natural drainage features including floodplains, natural drainage ways, and natural depressions that store water or allow it to infiltrate into the ground. These features are collectively referred to as the "Natural Drainage Ways" (NDW). Preserving the NDW will help ensure that stormwater runoff can continue to be conveyed and disposed of at its natural location. Preservation also increases the opportunity to use the predominant systems as regional stormwater facilities. Refer to Section 8 and the 2008 Stormwater Facility Plan Update for more information on NDW. IV. Stormwater runoff shall be discharged in the same manner and at the same location as in the pre -developed condition. Stormwater runoff shall not be concentrated onto down -gradient properties where sheet flow previously existed and shall not be diverted to points not receiving stormwater runoff prior to development. V. Applicability a. All projects shall comply with this Basic Requirement regardless of whether they meet the regulatory threshold. 1 Post -developed flow is equal to the release from detention facility plus the bypass flow 2 The emergency overflow shall direct the 100-year post -developed flow safely toward the downstream conveyance system 40 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.217 VI. Design Criteria a. Natural and Constructed Channels: Constructed and natural channels shall be designed with sufficient capacity to convey, at a minimum, the depth associated with the 100-year design storm event peak flow rate, assuming developed conditions for on -site tributary areas and existing conditions for any off- site tributary areas. Refer to Section 4.8 for additional criteria. b. Culverts under roadways or embankments: A culvert is a short pipe used to convey flow under a roadway or embankment. Culverts are used to pass peak flow from defined drainage ways identified on contour maps. New culverts shall be designed with sufficient capacity to convey the 100-year design storm event assuming developed conditions for the on -site basin and existing conditions for the off -site basin. C. Gutters: Gutter flows in roadways shall allow for the passing of vehicular traffic during the 10-year design storm event by providing non -flooded zones. For paved roadways, the non -flooded width requirement varies with the road classification. The design shall meet the criteria specified in Section 4.8. d. Storm Drain Systems and Inlets: The 10-year 24-hr design storm shall be used to size the conveyance system regardless of the method used to size the disposal facility. Enclosed Systems: Enclosed systems may surcharge or overtop drainage structures for storm events that exceed the drainage facility design storm, as long as an overflow path is provided, wherever possible. The overflow path shall be capable of conveying the 100-year storm event and should either drain toward the natural discharge point of the contributing basin (preferred) or away from adjacent buildings, residences, etc. so as to avoid adverse impacts due to flooding. F. BASIC REQUIREMENT NO. 6 — EROSION AND SEDIMENT CONTROL I. During the construction phase, sediment -laden runoff can enter newly constructed or existing drainage facilities, thus reducing their infiltration or treatment capacity and their lifetime of operation, or increasing maintenance costs. II. Controlling erosion and preventing sediment and other pollutants from leaving the project site during the construction phase is achievable through implementation and selection of BMPs that are appropriate both to the site and to the season during which construction takes place. 41 CHAPTER 4 — STORMWATER DESIGN SECTION 4.2.2G III. The objectives of the Erosion and Sediment Control (ESC) plan are to: a. Protect existing or proposed stormwater management infrastructure; b. Minimize the impacts of erosion, sedimentation and increased runoff caused by land -disturbing activities on private property, public roads and rights -of - way, and water bodies; and, Protect water quality. IV. Applicability a. A City Stormwater Management Permit for construction sites is required for land -disturbing activities which include, but are not limited to, excavation, planting, tilling, and grading, which disturbs the natural or improved vegetative ground cover so as to expose soil to the erosive forces of rain, stormwater runoff or wind. All installations and maintenance of franchise utilities such as telephone, gas, electric, etc., shall be considered land disturbing activities. b. The following land -disturbing activities require a City Stormwater Management Permit: i Any activity where the total volume of material disturbed, stored, disposed of or used as fill exceeds five (5) cubic yards; or, ii Any activity where the area disturbed exceeds one thousand (1,000) square feet provided it does not obstruct a watercourse, and is not located in a floodplain. C. A City Stormwater Management Permit for construction sites may not be required for all situations; however that does not relieve the owner from the responsibility of controlling erosion and sediment during construction nor the liability for damage claims associated with adverse impacts on off -site properties. G. BASIC REQUIREMENT NO. 7 — OPERATION AND MAINTENANCE I. To ensure that stormwater control facilities are adequately maintained and properly operated, documentation describing the applicable preventive maintenance and recommended maintenance schedule shall be prepared and provided to the entity responsible for maintaining the stormwater system. II. For stormwater control facilities outside of the public road right of way, the project owner shall provide the financial means and arrangements for the perpetual maintenance of the drainage facilities. Owners shall operate and maintain the facilities in accordance with an operation and maintenance plan that meets the criteria specified in Section 4.10. 42 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.IA III. Applicability a. All projects that meet the regulatory threshold and that propose drainage facilities or structures shall comply with this Basic Requirement. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2. 4.3 DRAINAGE SUBMITTAL 4.3.1 INTRODUCTION A. This Section describes the contents of a Drainage Submittal and provides a framework for preparing the submittal in order to promote consistency. Specific best management practices (BMPs), design methods and standards to be used are contained in Sections 4.4 through 4.10. Properly drafted construction engineering plans and supporting documents will help facilitate the operation and maintenance of the proposed system long after its review and acceptance. B. The Drainage Submittal is a comprehensive report containing all of the technical information and analysis necessary for regulatory agencies to evaluate a proposed new development or redevelopment project for compliance with stormwater regulations. Other supporting documentation shall be submitted as needed. Contents of the Drainage Submittal will vary with the type and size of the project, individual site characteristics, and special requirements of the City Engineer. The "trigger" for requiring compliance with this basic requirement is defined as "the addition or replacement of 10,000 square feet or more of impervious surfaces at full development. 4.3.2 APPLICABILITY A. A Drainage Submittal is generally required for any land -disturbing activity. Section 4.2.1 summarizes the types of activities that require a Drainage Submittal as well as those that are exempt. 4.3.3 DRAINAGE REPORT A. INTRODUCTION I. The purpose of the Drainage Report is to identify drainage impacts resulting from land development activities and determine the improvements necessary to control the increase in stormwater runoff and to treat the pollutants that can adversely impact water quality. II. A Drainage Submittal package is required with the engineers report as defined in the Construction and Design Standards. lII. The Drainage Report shall be inclusive, clear, legible, and reproducible. An uninvolved third party shall be able to review the Drainage Submittal and determine whether all applicable standards in this manual have been met. The basic elements of a Drainage Report are summarized in the following sections. 43 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.313 I. The drainage report narrative shall include the following elements: a. Project Description: The project description shall include information about the size of the project, the number of lots proposed, the project location, and background information relevant to drainage design, including topography, surface soils, surface and vegetative conditions, etc.; b. Geotechnical Information: This part of the narrative shall summarize the geotechnical site characterization (GSC) for the project including recommended infiltration rates and on -site soil descriptions; Pre -Development Basin Information: This information shall summarize the pre -development drainage patterns for all basins contributing flow to, on, through, and from the site. This section shall include all assumptions and justifications used to determine curve numbers and/or runoff coefficients used in the analysis. The narrative shall identify and discuss all existing on -site and/or off -site drainage facilities, natural or constructed, including but not limited to NDW, conveyance systems, and any other special features on or near the project; d. Post -Development Basin Information: This information shall summarize all assumptions used to determine the characteristics of the post -developed basins, such as the size of roofs and driveways, and the curve numbers and/or runoff coefficients used in the analysis. In addition, a table shall be included that summarizes the impervious and pervious areas for each sub -basin; Wetland Analysis: A wetland analyses is required for all new development and redevelopment. A wetland checklist, located in APPENDIX A , is required to be completed and submitted with the drainage report. The Wetland checklist helps to identify if wetland resources may be present and further wetland assessment is required. If "yes" is checked for any wetland indicators on the checklist, a Wetland Assessment outlined in the Kalispell Stormwater Quality Management Plan is required. The assessment must be performed by a wetland professional trained and familiar with the current US Army Corps of Engineers Regional Supplements for Wetland Delineations and the most recent Army Corps of Engineers guidance for Jurisdictional Determinations. Refer to City of Kalispell Stormwater Quality Management Plan for additional details; the Plan can be obtained from the Kalispell Public Works Department. ; f. Down -Gradient Anal This analysis shall identify and discuss the probable impacts down -gradient of the project site; 44 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.313 g. Methodology: The hydraulic methods and storm events used in sizing the drainage facilities, including the BMPs proposed for the project, shall be discussed; h. Water Quality Treatment: A discussion of treatment requirements, based on the criteria in Section 6 and the City of Kalispell Stomwater Quality Management Plan, shall be included; Results: The results of the calculations and a description of the proposed stormwater facilities shall be included. When applicable, a table comparing the pre -developed and post -developed conditions including rates and volumes shall also be included. A table shall be provided when applicable, summarizing the maximum water elevation of the facilities for the design storms, outflow structure information, the size of facilities "required" by the calculations, and the size of the facilities "provided" in the proposed design; j. Operational Characteristics: Sufficient information shall be provided about the operation of the stormwater system so that an uninvolved third party can read the report and understand how the proposed system will function under various conditions; k. Perpetual Maintenance of Facilities: A discussion shall be included of the provisions set forth to operate and maintain the drainage facilities. The project owner's mechanism for funding the operation and maintenance for stormwater facilities, including sinking fund calculations, shall be included (refer to 4.10.1F for more information); Off -Site Easements: The anticipated location of any off -site easements shall be identified either on the basin map or in a separate schematic. Off -site easements will be required for proposed stormwater conveyance or disposal facilities outside the project boundaries. These easements shall be obtained and recorded prior to the acceptance of the final Drainage Submittal (refer to Section 10 for more information); and, in. Regional Facilities: A discussion of any expected future impacts on or connections to existing or proposed regional facilities shall be included (refer to Section 4.7.12). 45 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.3C C. FIGURES I. Basin Map a. The drainage report shall include a basin map. Both a pre -developed and post -developed basin map shall be provided. The minimum elements required include the following: i Vicinity map, project boundaries, and section, township, and range; ii Basin limits: A) Basin limits shall include on -site, off -site, and bypass areas contributing runoff to or from the project. iii In all cases, the engineer shall field -verify the basin limits, including any contributing off -site areas, and shall describe how the basin limits were determined; iv Drainage basins shall be clearly labeled and correlated with the calculations; v Time of concentration routes, with each segment clearly labeled and correlated with the calculations; vi Labeled topographic contours: A) Contours shall extend beyond the project or drainage basin boundaries to the extent necessary to confirm basin limits used in the calculations; B) For commercial projects, spot elevations may be acceptable in lieu of contours on post -developed basin maps; C) Projects in an urban area shall use a maximum contour spacing of 1 foot; and, D) At the discretion of the City Engineer, projects outside an urban area, such as a large lot subdivision, may use the best available topographic information, but not greater than 2 maximum contour spacing of 2 feet. vii Any drainage way including, but not limited to, NDW, constructed drainage features, wetlands, creeks, streams, seasonal drainage ways, closed depressions, ditches, culverts, storm drain systems, and drywells; viii Floodplain limits, as defined by FEMA or other studies; ix Any geologically hazardous areas; x Footprint of proposed drainage facilities such as ponds, infiltration facilities, pipes, NDW, and ditches; xi North arrow and scale; xii Existing and proposed easements, parcel land, open space, parkland; and, xiii Adjacent streets. 46 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.31) II. Other Figures a. Site photos; b. Soils map; C. Any graphs, charts, nomographs, maps, or figures used in the design, when applicable; and, d. If infiltration is proposed, a geotechnical site characterization is typically required. As part of that study, a geologic cross-section of the stormwater disposal area drawn to scale shall be included. The proposed stormwater disposal facilities shall be superimposed on the cross-section. All relevant geologic units shall be clearly identified including the target disposal layer and limiting layers. D. CALCULATIONS I. Calculations shall be presented in a logical format and provide sufficient information to allow an uninvolved third party to reproduce the results. All assumptions, input and output data, and variables listed in computer printouts and hand calculations shall be clearly identified. Basins and design storm events shall be clearly identified on all calculations. II. The Drainage Report shall incorporate all calculations used to determine the size of the facilities. Typical calculations include, but are not limited to: a. Hydrologic/hydraulic calculations including pre- and post -developed peak rate and volume calculations, routing calculations, design information for outflow structures, orifice information, a pond volume rating table or pond volume calculations, etc.; b. Time of concentration calculations; C. Curve number (CN) or runoff coefficient (C); d. Water quality treatment calculations; e. Inlet capacity and bypass calculations; f. Detention/retention storage capacities; g. Calculations for ditches and natural drainage ways; h. Culvert and pipe calculations; i. Non -flooded width calculations for curbs and gutters; and, j. Energy dissipation calculations. III. Refer to Sections 4.5 through 4.8 for additional information regarding the above calculations. 47 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.3E E. DOWN -GRADIENT ANALYSIS I. The purpose of a Down -Gradient Analysis is to inventory natural and constructed down -gradient drainage features and to identify and evaluate adverse down -gradient impacts that could result from the proposed project. Adverse is defined as a down gradient property receiving more standing or flood water on their property than the pre -developed condition. Common adverse impacts of land development include erosion, flooding, slope failures, changed runoff patterns and reduced groundwater recharge (to springs, streams, wetlands and wells, etc.). Proposed drainage facilities are to be designed to mitigate adverse impacts identified in the Down -Gradient Analysis. II. A Down -Gradient Analysis is required for all projects. The level of detail required will vary depending on the location and complexity of the project. At a minimum the analysis shall extend a quarter of a mile down gradient and may be limited in scope by lack of access to adjacent properties. III. This analysis shall include: a. A visual inspection of the site and down -gradient area by the engineer that extends to the location where adverse impacts are anticipated to be negligible; b. A site map that clearly identifies the project boundaries, study area boundaries, down -gradient flow path, and any existing or potential areas that have been identified as problematic; C. Pre and post development hydraulic (rate and volume) capacities for the 10 and 100-yr 24-hr storm events. d. A written summary addressing the following items: i Existing or potential off -site drainage problems that may be aggravated by the project; ii The condition and capacity of the conveyance route including all existing and proposed elements, potential backwater conditions on open channels, constrictions or low capacity zones, surcharging of enclosed systems, or localized flooding; iii The presence of existing natural or constructed land features that are dependent upon pre -developed surface or subsurface drainage patterns; iv Potential changes to groundwater characteristics that may negatively impact sub -level structures, foundations, or surface areas due to an increased amount or increased frequency or duration of groundwater intrusion; v Existing or potential erosive conditions such as scour or unstable slopes on -site or down -gradient of the project; and, vi Flood areas identified on FEMA maps. 48 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.4A e. If there are existing or potential off -site drainage problems down -gradient of the project, it shall be demonstrated that the proposed stormwater disposal system has been designed to meet all of the following conditions: i The stormwater runoff leaves the site in the same manner as that of the pre -developed condition; ii Reduced or increased groundwater recharge has been considered with respect to potential adverse impacts on down gradient features; and iii The proposed design does not aggravate or impact an existing drainage problem or create a new drainage problem. f. If down -gradient surface release is at a rate or volume greater than the pre - developed condition, then potential adverse impacts on down gradient property natural or constructed drainage channels due to an increase in stormwater rate, volume, velocity, and flow duration shall also be addressed in detail. 4.3.4 ROAD AND DRAINAGE PLANS A. INTRODUCTION Construction drawings shall be submitted for review by the City Engineer. The submittal and acceptance process shall be in accordance with the City standards and specifications. All plan sheets for every submittal shall be signed and dated by the project owner, or his authorized agent, labeled Construction Plans, and all plan sheets shall be stamped, signed, and dated by the project engineer. B. MINIMUM PLAN ELEMENTS I. The road and drainage plans shall provide enough detail for a third party to construct the proposed facilities per the engineer's design. At a minimum, the plans shall meet the criteria of the City standards and specifications, and provide the following information: a. Flow line and/or spot elevations, slopes, lengths, and cross -sections of ditches; b. Rim elevations of inlet grates, drywells, and other structures; C. A rp cfile of the stormwater conveyance system including pipes, culverts, ditches and connections, where applicable. The profile shall include the sizes, material types, lengths, slopes, and invert elevations of all conveyance elements; d. Existing and proposed lot grading plans; The minimum depth from finish grade to pipe invert and the minimum pipe slope necessary to satisfy the freeboard and self-cleaning velocity requirements shall be provided; 49 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.4C f. Where drainage infrastructure such as roadside swales or parallel conveyance ditches or channels may interfere with driveway locations, driveway locations shall be fixed as part of the road and drainage plans and shown on the plans; g. Record drawing information, including invert elevations of any existing drainage system elements that will be used in the new design; h. Construction details drawn to scale or a referenced standard drawing for all structures; Drainage easements with all survey information shown and a recording number if applicable; Grading plan for drainage facilities and swales. The grading plan shall include existing and proposed contours and catch points. A cross- section of each pond or swale shall be provided in the plans, showing bottom elevation, drainage structure elevation, maximum water surface elevation for the design storm(s), inlet and outlet elevations, berm elevation and slopes, landscaping and vegetation requirements, compaction requirements and keyway location and dimensions; k. Each drainage pond/swale corner, pipe inlet or outlet, pipe system angle point, ditch, and drainage structure, shall be horizontally defined with respect to property corners, street stationing, or a coordinate system; and, Material gradation, thickness, and dimensions of riprap pads C. REVISIONS AFTER PLAN ACCEPTANCE When changes to the design are necessary, acceptance of any proposed plan changes shall be obtained in writing from the City Engineer. The proposed revisions shall be stamped and signed by an engineer and submitted to the Public Works Department for review and acceptance prior to construction. The submittal shall include: A brief description of the proposed changes and the purpose for the change; b. Substitute pages of the originally accepted construction plans that include the proposed changes; and, C. Calculations and supporting documentation for the proposed change demonstrating that the proposed modified design is at least equivalent to the originally accepted design. 50 CHAPTER 4 — STORMWATER DESIGN SECTION 4.3.5A 4.3.5 OTHER SUBMITTAL ELEMENTS A. As determined by the City Engineer, the following items shall be included as part of the Drainage Submittal: I. A geotechnical site characterization, which may also include a sub -level structure feasibility analysis, pavement analysis, pavement subgrade sampling, down -gradient analysis, etc; II. An erosion and sediment control plan; III. A draft copy of the Conditions, Covenants and Restrictions (CC&Rs) for the homeowners' association in charge of operating and maintaining the drainage facilities (refer to 4.10); IV. An operations and maintenance manual (refer to 4.10.1 D); V. A financial plan (refer to 4.10.IF); and, VI. On -site and/or off -site easement documentation (refer to 4.10.2C). 4.4 GEOTECHNICAL SITE CHARACTERIZATION 4.4.1 INTRODUCTION A. This Section outlines the minimum requirements for a geotechnical site characterization (GSC), which is used in developing recommendations for stormwater disposal and determining the feasibility of constructing sub -level structures. A professional engineer currently licensed in the State of Montana is required to perform the GSC. Hydrogeologists and engineering geologists may prepare geotechnical site characterization studies, excluding structural, foundation and pavement design. B. The following geotechnical studies, if required, can be performed at the same time as the GSC: I. Geohazard analysis; II. Pavement subgrade evaluation; III. Down -gradient analysis; IV. Embankment recommendations for proposed disposal facilities that would impound stormwater; and V. Recommendations for all cut and fill slopes; VI. And floodplain analysis. C. Contact the City Engineer for specific requirements with regard to geohazardous areas and road surfacing. The requirements of this Section are in addition to any field or laboratory testing that may be required, or recommended by the project engineer, with regard to footings, foundations, utility work, etc. 51 CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.1 D D. In known drainage problem areas, the geotechnical engineer may make recommendations on the feasibility of sub -level structures based on the information available from the initial site investigation. 4.4.2 APPLICABILITY A. A GSC will be required for most projects. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2. The scope and geographic extent of the investigation may vary depending on the general location and setting of the site, the characteristics of the target soil layer, and whether there are known or anticipated drainage problems in the vicinity of the site. B. A GSC is required for: I. Projects proposing infiltration (infiltration facilities, detention facilities receiving credit for pond bottom infiltration, etc.), or non-standard drainage systems; II. Projects located within or draining to a drainage problem or study area as recognized by the City Engineer; or, I11. Projects with proposed sub -level structures, i.e., footings, foundations, and utility work. 4.4.3 GEOTECHNICAL SITE CHARACTERIZATION REPORT A. The following are minimum requirements for the GSC: The Study shall include: a. A surface reconnaissance of the site and adjacent properties to assess potential impacts from the proposed stormwater system and to verify that the conditions are consistent with the mapped information. Typically, the evaluation should extend a quarter of a mile down gradient. Where access to adjacent properties is unavailable, the project owner shall rely upon the best known information for the area, supplemented with information available from the City Engineer, including any existing geotechnical engineering reports or studies for sites in the vicinity; b. A review of available geologic, topographic, and soils, and identify any site conditions that could impact the use of storm drainage systems or the construction of sub -level structures. This review shall include all available previous geotechnical engineering reports or studies for sites in the vicinity; and, C. An evaluation of the potential impacts of groundwater on the proposed storm drainage facilities, roadways and proposed underground structures, when a seasonally high groundwater table is suspected. 52 CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.3A II. The Report Narrative shall include: a. A brief project description including size, number of lots proposed, project location (section, township and range), and background information relevant for drainage design; b. A discussion of the study investigations; C. A description of the soil units on the site and in the vicinity of the site; d. A description of the site including surface, soil, and groundwater conditions, etc; and, e. Conclusions and recommendations. III. The Site Plan shall include: a. Project boundaries (including all existing and proposed property lines); b. Labeled topographic contours, extending beyond the project and drainage basin. Projects in an urban area shall use a maximum contour spacing of 1 foot; C. Location of the soil units identified; d. Location of significant structures, properties or geologic features on site and in the project vicinity; e. Location of existing natural or constructed drainage features on site and in the project vicinity; and, f. Location of proposed site infrastructure including roadways and drainage features such as ponds, drywells, etc. IV. Test Method Documentation shall include: a. A map with the location of all subsurface field explorations and any in - place field tests; b. A description of any difficulties encountered during excavation and testing; C. A description of the equipment used to perform the field explorations or tests. When applicable, describe the type of fabric lining and gravel backfill used; d. Logs of subsurface explorations which shall identify the depth to groundwater, the presence of any limiting layers and the target soil layer; include test pit or excavation dimensions, with photographs, where applicable; e. Report test data in a format that includes time of day, flow meter readings, incremental flow rates, observed head levels, water depths and total flow volumes in the test pit or infiltrometer; and, 53 CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.313 f. A description of the condition of any existing facilities being tested, noting any silt build-up, water level, connections to other structures (including distance to inverts of any interconnecting pipes), measured depths and dimensions, etc. V. Results of field and laboratory testing conducted, including the grain size analysis represented both graphically and in tabular format; VI. A report on the actual and proposed design outflow rates for test pits; VII. Results of the sub -level structure feasibility study and a summary of the down - gradient analysis as applicable; and, VIII. A geologic cross-section of the stormwater disposal area drawn to scale, with the proposed stormwater disposal facilities superimposed on the cross-section. All relevant geologic units shall be clearly identified including the target disposal layer and limiting layers. C f \1 _.:•�_._ •l I. The subsurface exploration, testing, and associated engineering evaluations are necessary to identify permeable soils and to determine the thickness, extent, and variability of the soils. This information is necessary to properly design stormwater disposal facilities. II. Field explorations and laboratory testing shall be conducted under the direct supervision of a civil engineer, a geotechnical engineer, a hydrogeologist , or an engineering geologist. III. Test Methods a. Soil infiltration rates shall be determined using one or more of the following methods for new development or redevelopment with greater than or equal to 10,000 square feet of impervious surface: i The ASTM D 3385-88 Double -ring Infiltrometer Test: This test method is used for field measurement of infiltration rate of soils; ii EPA Falling Head Percolation Test Procedure (Design Manual On - site Wastewater Treatment and Disposal System, EPA, 1980; iii The Pilot Infiltration Test Procedure: This test method uses field data to estimate the outflow rates of subsurface disposal facilities (refer to Stonmwater Quality Management Plan: Pilot Infiltration Test Procedure Appendix C); iv Additional or alternate test methods, upon approval from the City Engineer. b. For new development or redevelopment with less than 10,000 square feet of impervious surface the soil infiltration rates rate shall be determined by one of the above methods or: Montana Department of Environmental Quality (DEQ) Circular 4 Percolation Test. 54 CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.3C IV. Minimum Requirements a. The following minimum requirements, when applicable, shall be met for field explorations and laboratory testing when subsurface disposal is proposed: i Test borings and/or test pits shall be located within the footprint of proposed stormwater disposal facilities; and, ii For each facility, a minimum of one subsurface exploration shall be performed for up to 1,500 square feet of disposal area. Another subsurface exploration shall be performed for each additional 1,500 square feet, or fraction thereof, of disposal area. For a linear roadside swale, a minimum of one subsurface exploration shall be performed every 500 feet, staggered on both sides of the road, unless site conditions or test results indicate that additional explorations are necessary. Subsurface explorations and sampling shall be conducted according to applicable standards of the American Society for Testing and Materials (ASTM). V. Post -Construction Testing a. Newly constructed infiltration facility will require a full-scale successful test prior to project engineer certification. Refer to APPENDIX B2 for flood test methods. Contact the City Engineer for additional information. C. SUB -LEVEL STRUCTURE FEASIBILITY I. If sub -level structure construction is being considered, a sub -level structure feasibility study is required. Field explorations and laboratory testing shall be conducted under the direct supervision of a geotechnical engineer, hydrogeologists, or an engineering geologist. Test boring shall be performed per the geotechnical engineer, a hydrogeologist, or an engineering geologist recommendation or at minimum of one per 10,000 square feet. Ground water shall be monitored during seasonal high ground water conditions. The sub- level structure feasibility study shall include the following, at a minimum: a. A layout of the site showing lot lines and lot and block numbers; b. Identification by lot and block number of sites where sub -level structure construction is feasible. Provide recommendations with details of construction, i.e., maximum below grade floor elevations, minimum drainage system requirements, and any site specific recommendations; C. Discussion of the effects of hydrostatic pressure that may lead to basement flooding and recommendations as to the effectiveness of waterproofing; d. If infiltration is proposed as a method for stormwater disposal, discussion of any potential adverse impacts on proposed sub -level structures, taking into consideration the contribution of imported water (due to lawn watering, etc.); and, 55 CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.3C C. Identification of locations where sub -level structure construction is not feasible. When field and research data indicate season high ground water is 1) below 15 feet, basements and crawl spaces would be allowed, 2) between 5 feet to 15 feet, basement construction would be prohibited, 3) at 5 feet or less, both basement and crawl space would be prohibited. II. Language regarding sub -level structure restrictions shall be placed or referenced on the face of the plat. If a potential buyer would like to construct a sub -level structure in an area deemed not feasible, then a site specific geotechnical evaluation shall be performed by a geotechnical engineer for the individual lot prior to a building permit being issued. III. Recommendations shall be summarized and provided electronically in Microsoft Excel, per the format found in Table 5. we CHAPTER 4 — STORMWATER DESIGN SECTION 4.4.3C Table 5 - Exam le Sub -level Structure F asibility Summary /'1 O C• ^I y �N ri o PLO W A a a Summary of Geotechnical Recommendations131 C= 15 feet Based upon the clean nature of the soils at the sub- level GrW=25 elevations and the depth to groundwater, footing drains are feet 13=30 not required. However, below- grade walls shall be well x U feet reinforced to reducing cracking and thoroughly damp -proofed with a water- resistant bituminous emulsion or modified cement M base coating. Backfill material shall consist of only clean granular material which is free of fine-grained soils, organic material, debris and large rocks. GrW=13 Below -grade walls shall be well reinforced to reduce cracking and feet waterproofed with a membrane (per IRC) which is lapped and sealed from the top of the footing to the finished grade. An under slab waterproof membrane (per IBC) which is lapped and sealed shall be integrated with the wall membrane. Backfill material shall — consist of only clean granular material which is free of fine- 0 0 grained soils, organic material, debris and large rocks. Walls and footings shall have a drain system with cleanouts, emptying a minimum of 15 feet in a down -slope direction away from structures. Precautions shall be taken not to excavate a closed depression over rock or clay that is intended to dispose of sump water from a foundation drain system. GrW=6 Due to the very shallow presence of groundwater, sub -level feet B=10 structures are not recommended on these lots. If a crawl space is N °O feet proposed, a drain system with cleanouts shall be provided that oempties a minimum of 15 feet in a down -slope direction away pa �° from structures. Precautions shall be taken not to excavate a closed depression over rock or clay that is intended to dispose of sump water from foundation drain system. 1 Maximum depth measured from original pre-construction/pre-grading ground surface elevation or existing ground surface, whichever provides a greater distance between the lowest floor elevation and the limiting layer. 2 GrW=groundwater, B=bedrock or basalt, C=clayey-silty soils 3 Refer to the Geotechnical Report for this project for further information, which may include construction details that support these recommendations. 57 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.1A 4.5 HYDROLOGIC ANALYSIS AND DESIGN 4.5.1 INTRODUCTION A. This Section provides the tools for estimating peak flow rates and volumes for sizing conveyance, treatment, and flow control facilities. Standard flow control facilities are detention, retention and infiltration facilities. Flow control facilities are necessary to mitigate potential adverse impacts on down -gradient properties due to the increase in stormwater runoff caused by land development. B. The peak rate of stormwater runoff from any proposed land development to any natural or constructed point of discharge downstream shall not exceed the pre - development peak rate of runoff. The post development volume of runoff can exceed the pre -development volume of runoff when the required down -gradient analysis demonstrates that there will be no adverse impacts on down gradient properties or existing natural and constructed conveyance systems. C. Stormwater runoff from a developed site shall leave the site in the same manner and location as in the pre -developed condition. Flow may not be concentrated onto down- gradient properties where sheet flow previously existed. Drainage shall not be diverted from a proposed development and released downstream at points not receiving stormwater runoff prior to the proposed development. 4.5.2 HYDROLOGIC ANALYSIS METHODS A. The following methods shall be used for the design of flow control facilities and conveyance systems: I. The most commonly used Curve Number Method is the Natural Resources Conservation Service Urban Hydrograph Method (NRCS Method). The Natural Resource Conservation Service (NRCS) Curve Number (CN) Method can be used to calculate: a. Peak flow rates; b. Flow control volumes; and, C. Water quality volume (WQv) . II. The Level Pool Routing Method can be used to route hydrographs; and, III. The Rational Method can be used to estimate peak runoff rates. 4.5.3 CURVE NUMBER METHOD A. INTRODUCTION I. Single -event hydrograph methods based on the curve number equation can be used in combination with a routing technique to size stormwater facilities. These methods are used to develop hydrographs to estimate the peak flow rate and volumes for a specific design storm. 58 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3B B. CURVE NUMBER METHOD THEORY 1. This section presents a general description of this methodology, for additional information refer to the National Engineering Handbook —Section 4: Hydrology (SCS 1985), or the Natural Resource Conservation Service web site section of hydraulics and hydrology. The amount of runoff from a site calculated using the Curve Number Method depends on the precipitation at the site and the natural storage capacity of the soil. The curve number equation and the NRCS rainfall excess equation are shown in Equation 1 and Equation 2. Equation 1 S = 1CN0 — 10 Where: S = maximum storage volume of water on and within the soil (inches); and, CN = Curve Number (dimensionless) Equation 2 Q = (P-O'Zs)Z ; Q = 0 for P < 0.2 (P+o.ss) Where: Q = runoff (inches); S = maximum storage volume of water on and within the soil (inches); P = precipitation (inches); and, 0.2S = initial abstraction; the fractional amount estimated as intercepted, evaporated and/or absorbed by the soil (inches). C. LIMITATIONS Alternative methods approved by the City Engineer shall be used when: a. The calculated depth of runoff is less than 0.5 inch; b. The value (P-0.2S) is a negative number; or, The weighted CN is less than 40. I1. For additional limitations, see the Soil Conservation Service's Technical Release No. 55 (Publication 210-VI-TR-55, Second Ed., June 1986). III. The City Engineer reserves the authority to limit discharge to public facilities. Regardless of the methodology used, if a given method yields a runoff volume or rate that is inconsistent with the physical site characteristics, the engineer will be required to provide additional supporting documentation. 59 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.31) D. BASIN AREAS The basin area must reflect the actual runoff characteristics as closely as possible and be consistent with the assumptions used. The impervious and pervious areas must be estimated from best available plans, topography, or aerial photography, and verified by field reconnaissance. E. HYDROLOGIC SOIL GROUP CLASSIFICATION I. The determination of a site's hydrologic soil group(s) can be found by NRCS Web Soil Survey Web site. The NRCS has classified over 4,000 soil types into the following four soils groups: a. Group A soils have high infiltration rates, even when thoroughly wetted, and consist chiefly of deep, well -to -excessively drained sands or gravels. These soils have a high rate of water transmission and low runoff potential. b. Group B soils have moderate infiltration rates when thoroughly wetted, and consist chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission and moderately low runoff potential. C. Group C soils have slow infiltration rates when thoroughly wetted, and consist chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of transmission and moderately high runoff potential. d. Group D soils have very slow infiltration rates when thoroughly wetted, and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious materials. These soils have a very slow rate of transmission and high runoff potential. F. CURVE NUMBERS (CN) I. Curve numbers (CN) indicate the runoff potential of a watershed. The higher the CN value, the higher the potential for runoff. The CN takes into consideration the hydrologic soil group, land use, and cover. II. Table 7 lists CN values for agricultural, suburban, and urban land use classifications. These values are for Antecedent Runoff Condition (ARC) II, which is defined below. CN values will need to be converted to ARC III for calculating Water Quality volumes. CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3F III. Weighting Curve Numbers: a. Basins often include areas with differing curve numbers based on their soils, land use, and cover. Overall CNs for these basins are determined by weighting the CN for each area based on the size of the area. Weighted curve number method can be used for flow control, peak flow rate calculation and Water Quality Volume (WQv) calculations. IV. Antecedent Runoff Condition — Curve Number Adjustment: a. The moisture condition in a soil prior to a storm event is referred to as the antecedent runoff condition (ARC). The NRCS developed three antecedent runoff conditions: i ARC I (Dry Condition): soils are dry but surface cracks are not evident. ii ARC II (Average Condition): soils are not dry or saturated. The CN values listed in Table Tare applicable under this condition and do not account for snowmelt or runoff on frozen ground conditions. iii ARC III (Wet Condition): soils are saturated or near saturation due to heavy rainfall or light rainfall and low temperatures within the last 5 days. ARC III conditions model the winter months. iv Table 6 shall be used to adjust the CN values from ARC II to ARC III. 61 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3F Table 6 - Curve Numbers Based on Antecedent Runoff Conditions (ARQ1111113 CN ARC II CN ARC I CN ARC III CN ARC II CN ARC I CN ARC III 100 100 100 76 58 89 99 97 100 75 57 88 98 94 99 74 55 88 97 91 99 73 54 87 96 89 99 72 53 86 95 87 98 71 52 86 94 85 98 70 51 85 93 83 98 69 50 84 92 81 97 68 48 84 91 80 97 67 47 83 90 78 96 66 46 82 89 76 96 65 45 82 88 75 95 64 44 81 87 73 95 63 43 80 86 72 94 62 42 79 85 70 94 61 41 78 84 68 93 60 40 78 83 67 93 59 39 78 82 66 92 58 38 76 81 64 92 57 37 75 80 63 91 56 36 75 79 62 91 55 35 74 78 60 90 54 34 73 77 59 89 50 31 70 1. Curve number conversions for different ARC are for the case of initial abstraction (I,) = 0.2 S. Initial abstraction represents all water losses before runoffbegins (water retained in surface depressions, water intercepted by vegetation, evaporation, infiltration, etc.) 2. Source: U.S. Soil Conservation Service National Engineering Handbook Table 10.1 (MRCS). 3 ARC I values are shown for reference only. 62 CHAPTER 4 — STORMWATER DESIGN SECTION 0 Table 7 - Runoff Curve Numbers Antecedent Runoff Conditions (ARCI II Group Group Group Group B Soils Open Space (lawns, parks, golf courses, cemeteries, landscaping, etc.)1'1: Poor condition (grass cover <50% of the area) 68 79 86 89 Fair condition (grass cover on 501/6 to 75% of the area) 49 69 79 84 Good condition (grass cover on >75% ofthe area) 39 61 74 80 Impervious Areas: Open water bodies: lakes, wetlands, ponds etc. 100 100 100 100 Paved parking lots, roofs, driveways, etc. (excluding right of way) 98 98 98 98 Porous pavers and permeable interlocking concrete (assumed as 85% impervious and 15% lawn): Fair lawn condition (weighted average CNs) 91 94 96 97 Gravel 76 85 89 91 Dirt 72 82 87 89 Pasture, Grassland, or Range -Continuous Forage for Grazing: Poor condition (ground cover <50% or heavily grazed with no mulch). 68 79 86 89 Fair condition (ground cover 50% to 75% and not heavily grazed) 49 69 79 84 Good condition (ground cover >75% and lightly or only occasionally grazed) 39 61 74 80 Cultivated Agricultural Lands: Row Crops (good) e.g. com, sugar beets, soy beans 64 75 82 85 Small Grain (good) e.g. wheat, barley, flax 60 72 80 84 Meadow (continuous grass, protected from grazing and generally mowed for hay) 30 58 71 78 Brush (brush -weed -grass mixture with brush the major element): Poor (<50% ground cover) 48 67 77 83 Fair (50% to 75% ground cover) 35 56 70 77 Good (>75% ground cover)121 30 48 65 73 Woods - grass combination (orchard or tree farm)131: Poor 57 73 82 86 Fair 43 65 76 82 Good 32 58 72 79 Woods: Poor (Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning) 45 66 77 83 Fair (Woods are grazed but not burned, and some forest litter covers the soil) 36 60 73 79 Good (Woods are protected from grazing, and litter and brush adequately cover the soil) 30 55 70 77 Herbaceous (mixture of grass, weeds, and low -growing brush, with brush the minor element) 141 Poor (<3 0% ground cover) 80 87 93 Fair (30% to 70% ground cover) 71 81 89 Good (>70% ground cover) 62 74 85 Sagebrush with Grass Understory 141 Poor (<3 0% ground cover) 67 80 85 Fair (30% to 70% ground cover) 51 63 70 Good (>70% ground cover) 35 47 55 I Composite CNs may be computed for other combinations of open space cover type. 2 Actual curve number is less than 30; use CN = 30 for runoff computations. 3 CNs shown were computed for areas with 50°/u woods and 50% grass (pasture) cover. Other combinations may be computed from CNs for woods and pasture. 4 Curve numbers have not been developed for group A soils. For a more detailed and complete description of land use curve numbers refer to Chapter 2 of the Soil Conservation Service's (NRCS)Technical Release No. 55 (Publication 210-VI-TR-55, Second Ed., June 1986). 63 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3G G. TIME OF CONCENTRATION I. Time of concentration is affected by the way stormwater moves through a watershed. Stormwater can move in the form of sheet flow, shallow concentrated flow, open channel flow, or some combination of these. The type of flow should be verified by field inspection. II. The time of concentration for rainfall shall be computed for all overland flow, ditches, channels, gutters, culverts, and pipe systems. When using the Curve Number Method, the time of concentration for the various surfaces and conveyances shall be computed using the procedures presented in this section. These procedures are based on the methods described in the Soil Conservation Service's Technical Release No. 55. III. Travel time (Tt) is the time it takes stormwater runoff to travel from one location to another in a watershed. Time of concentration (T j is the time for stormwater runoff to travel from the hydraulically most distant point to the point of discharge of a watershed. T, is computed by adding all the travel times for consecutive components of the drainage conveyance system as given by the following equation: Equation 3 T C = T ti + Tt2 + • • • + Tt,, Where: Tc = time of concentration (minutes); n = number of flow segments; and, Tt = travel time (minutes) is the ratio of flow length to flow velocity given by: Equation 4 Tt = L 60V Where: Tt = travel time, in minutes; L = flow length (feet); V = average velocity (feet/second); and, 60 = conversion factor (seconds to minutes). IV. Tc influences the shape and peak of the runoff hydrograph. Urbanization usually decreases Tc, thereby increasing the peak discharge. But Tc can be increased as a result of ponding behind small or inadequate drainage facilities including storm drain inlets and road culverts, or reduction of land slope through grading. Tc shall not be less than 5 minutes. 64 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3G V. Sheet Flow: a. Sheet flow is flow over plane surfaces and shall not be used over distances exceeding 300 feet. Use Manning's kinematic solution to directly compute Tt: Equation 5 T 0.42(ns*t)0-8 E 9 t = (p2)0.5(So)0.4 Where: Tt = travel time (minutes); ns = Manning's effective roughness coefficient for sheet flow (use Table 8); L = flow length (feet); P2 = 2-year, 24-hour rainfall (inches), (use Table 10); and, So = slope of hydraulic grade line (land slope, ft/ft). b. The friction value (ns) is used to calculate sheet flow. The friction value is Manning's effective roughness coefficient modified to take into consideration the effect of raindrop impact, drag over the plane surface, obstacles such as litter, depressions, crop ridges and rocks, and erosion and transportation of sediment. The ns values are for very shallow flow depths of about 0.1 foot and are only used for travel lengths up to 300 feet. Table 8 gives Manning's ns values for sheet flow for various surface conditions. VI. Shallow Concentrated Flow: a. After 300 feet, sheet flow is assumed to have developed into shallow concentrated flow. The travel time (Tt) for the shallow concentrated flow segment can be computed using Equation 4. The average velocity for shallow concentrated flow is calculated using the following equation: 65 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3G Equation 6 V = k So Where: V = velocity (feet/second); k = ks or kc, time of concentration velocity factor (feet/second); and, So = slope of flow path (feet/foot). b. Table 8 provides "k" for various land covers and channel characteristics with assumptions made for hydraulic radius using the following rearrangement of Manning's equation: z Equation 7 k = 1.49*R3 n Where: R = hydraulic radius; and, A) n = Manning's roughness coefficient for open channel flow (see Table 9). VII. Open Channel Flow: a. Open channels are assumed to exist where channels are visible on aerial photographs, where streams appear on United States Geological Survey (USGS) quadrangle sheets, or where topographic information indicates the presence of a channel. b. The kc values from Table 8 used in Equation 6 can be used to estimate average flow velocity. Average flow velocity is usually determined for bank - full conditions. After average velocity is computed the travel time (T,) for the channel segment can be computed using Equation 4. CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3G Table 8 - Friction Values (n and k) For Use In Computing Time of Concentration1111�1 Sheet Flow ns Bare sand 0.010 Smooth surfaces (concrete, asphalt, gravel, or bare hard soil) 0.011 Asphalt and gravel 0.012 Fallow fields of loose soil surface (no vegetal residue) 0.05 Cultivated soil with crop residue (slope < 0.20 feet/foot) 0.06 Cultivated soil with crop residue (slope > 0.20 feet/foot) 0.17 Short prairie grass and lawns 0.15 Dense grass 0.24 Bermuda grass 0.41 Range, natural 0.13 Woods or forest, poor cover 0.40 Woods or forest, good cover 0.80 Shallow, Concentrated Flow ks Forest with heavy ground litter and meadows (n = 0.10) 3 Brushy ground with some trees (n =0.06) 5 Fallow or minimum tillage cultivation (n = 0.04) 8 High grass (n = 0.035) 9 Short grass, pasture and lawns (n = 0.030) 11 Newly -bare ground (n = 0.025) 13 Paved and gravel areas (n = 0.012) 27 Channel Flow (Intermittent, R = 0.2) k, Forested swale with heavy ground litter (n=0.10) 5 Forested drainage course/ravine with defined channel bed (n=0.050) 10 Rock -lined waterway (n=0.035) 15 Grassed waterway (n=0.030) 17 Earth -lined waterway (n=0.025) 20 Corrugated metal pipe (n=0.024) 21 Concrete pipe (n=0.012) 42 Other waterways and pipes 0.508/n Channel Flow (Continuous Stream, R =0.4) k, Meandering stream with some pools (n=0.040) 20 Rock -lined stream (n=0.035) 23 Grassed stream (n=0.030) 27 Other streams, man-made channels and pipe 0.807/n 1 These values were determined specifically for sheet flow conditions and are not appropriate for conventional open channel flow calculations. 2 Source: WSDOT Highway Runoff Manual (2004) Table 413-5; Engman (1983); and the Florida Department of Transportation Drainage Manual (1986). 67 CHAPTER 4 - STORMWATER DESIGN SECTION 4.5.3G Table 9 - Suggested Values of Manning's Roughness Coefficient "n" For Channel Flow 111 Type of Channel and Description n [2] Type of Channel and Description nl�1 A. CONSTRUCTED CHANNELS 7. Very weedy reaches, deep pools, or floodways with heavy stand of timber and underbrush 0.100 a Earth, straight and uniform 1. Clean, recently completed 0.018 2. Gravel, uniform selection, clean 0.025 b Mountain streams, no vegetation in channel, banks usually steep, trees and brush along banks submerged at high stages 3. With short grass, few weeds 0.027 b Earth, winding and sluggish I No vegetation 0.025 1 Bottom: gravel, cobbles aYlfew boulders 0.040 2. Grass, some weeds 0.030 3 Dense weeds or aquatic plants in deep channels 0.035 2 Bottom: cobbles with large boulders 0.050 4. Earth bottom and rubble sides 0.030 B-2 Floodplains 5. Stony bottom and weedy banks 0.035 a Pasture, no brush 6. Cobble bottom and clean sides 0.040 1 Short grass 0.030 c Rock lined 2 High grass 0.035 1. Smooth and uniform 0.035 b Cultivated areas 2..Jagged and irregular 0.040 1. No crop 0.030 d Channels not maintained, weeds and brush uncut 2. Mature row crops 0.035 1. Dense weeds, high as flow depth 0.080 3 Mature field crops 0.040 2 Clean bottom, brush on sides 0.050 c Brush 3. Same, highest stage of flow 0.070 1 Scattered brush, heavy weeds 0.050 4 Dense brush, high stage 0.100 2 Light brush and trees 0.060 B. NATURAL STREAMS 3. Medium to dense brush 0.070 B1 Minor streams (top width at flood stage < 100 4. Heavy, dense brush 0.100 a Streams on plain d Trees 1 Clean, straight, full stage, no rifts or deep pools 0.030 1 _ Dense willows, straight 0.150 2. Cleared land with tree stumps, no sprouts 0.040 2 Same as No. 1, but more stones and weeds 0.035 3. Same as No. 2, but with heavy growth of sprouts 0.060 3 Clean, winding, some pools and shoals 0.040 4. Heavy stand of timber, a few down trees, little undergrowth, flood stage below branches 0.100 4. Same as No. 3, but some weeds 0.045 5. Same as No. 4, but more stones 0.050 Ca Sluggish reaches, weedy deep poo17 0.070 5. Same as above, but with flood stage reaching branches 0.120 I Source: WSDOT Highway Runoff Manual (2004) Table 4B-6; Engman (1983) and the Florida Department of Transportation Drainage Manual (1986). 2 The "n" values presented in this table are the "Normal" values as presented in Chow (1959). For an extensive range and for additional values refer to Chow (1959) 68 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3H H. PRECIPITATION MAPS The design 24-hour precipitation depths and recurrence interval used by Kalispell are provided in the table below. The precipitation isopluvial map data comes from National Oceanic and Atmospheric Administration (NOAA) Atlas 2, Volume IX, 1973. Table 10 - City of Kalispell 24-Hour Precipitation Depths Recurrence Interval 2-year 10-year 25-year 50-year 100-year 24-Hour Precipitation 1.4 2.0 2.4 2.8 3.0 Depth (inches) I. DESIGN STORM DISTRIBUTION The CN method requires the selection of, or the input of, a rainfall distribution and the precipitation associated with a design storm. The NRCS Type I 24-hour storm for the 10- and 100-year storm event storm distributions shall be used for sizing flow control facilities. J. PEAK DISCHARGE COMPUTATIONS For a selected rainfall frequency, the 24-hour rainfall (P) is obtained from NOAA Charts (see Table 10). CN value and total runoff (Q) for the watershed are computed according to the methods as outlined in Section 4.5.2A.III. The CN is used to determine the initial abstraction (Ia) from Equation 8. Equation 8 la = 0. 2 [(1cN°) — 101 Where: Ia = initial abstract (inches); and CN = curve number (dimensionless); II. The Ia/P ratio is a parameter that indicates how much of the total rainfall is needed to satisfy the initial abstraction. The precipitation value to be used in the ratio is the 24-hr rainfall for the return period of interest. If the Ia/P ratio is outside the range of 0.1 to 0.5, then the limiting values should be used, i.e., use 0.1 if less than 0.1 and 0.5 if greater than 0.5. The unit peak discharge (q„) is obtained from Figure 1. The time of concentration (T j and Ia / P ratio values are needed to obtain a value for q„ from the figure. CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.3J III. When sizing a mechanical treatment device for the water quality flow rate, use Equation 9 to calculate the peak discharge (qp). Equation 9 qp = qu * A * Q Where: qp = peak discharge (cfs) q,a = unit peak discharge (cfs/ac/in) A = drainage area (ac) Q = runoff (in) 06 07 06 M 01 0.2 O�3 0A 0.5 0,6 010SD91 5 10 Tne of concentration (T.), hours Figure I - Unit peak discharge (qu) for NRCS (SCS) type I rainfall distribution 70 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.4A 4.5.4 LEVEL POOL ROUTING METHOD A. This section presents a general description of the methodology for routing a hydrograph through an existing flow control facility, and for sizing a new flow control facility using hydrograph analysis. The "level pool routing" technique presented here is one of the simplest and most commonly used hydrograph routing methods. This method is described in Handbook of Applied Hydrology (Chow, Ven Te, 1964) and elsewhere, and is based upon the continuity equation: Inflow — Outflow = A Storage Equation 10 I1+I2 _ 01+02 = AS = S2 — Si 2 2 At Where: I = inflow at time 1 and time 2; O = outflow at time 1 and time 2; S = storage at time 1 and time 2; and, At = time interval, time 2 — time 1. B. The time interval, At, must be consistent with the time interval used in developing the inflow hydrograph. The At variable can be eliminated by dividing it into the storage variables to obtain the following rearranged equation: Equation 11 I1 + 12 + 2S1 — 01 = 02 + 2S2 C. If the time interval, At, is in minutes, the units of storage (S) are in cubic feet per minute, which can be converted to cubic feet per second by multiplying by 1 minute/60 seconds. The terms on the left-hand side of the equation are known from the inflow hydrograph and from the storage and outflow values of the previous time step. The unknowns 02 and S2 can be solved using the stage -storage and stage - discharge relationships for the storage facility being analyzed or sized. 4.5.5 RATIONAL METHOD A. The primary source of this section is the MDT Hydrology Manual, Chapter 7. The rational method is an allowable method for computing peak runoff rates. The rational method can be used for the design of conveyances and flow control discharge rates. 71 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.513 B. The peak flow rate is calculated using the following equation: Equation 12 Qp = C * I * A Where: Qp = peak flow rate (cfs); C = runoff coefficient (dimensionless units); I = rainfall intensity (inches/hour); and, A = drainage area (acres). C. Coefficients given in Table 12 and Table 13 are applicable for storms of 5-yr to 10-yr frequencies. The adjustment of the rational method for use with major storms can be made by multiplying the right side of the rational formula by a frequency factor Cf. The rational formula now becomes: Equation13 Qp=C*Cf*I*A I. The Cf values are listed in Table 11. The product of Cf times C shall not exceed 1.0. Table 11 - Freouencv Factors for Rational Formula Recurrence Interval (years) Cf 25 1.1 50 1.2 100 1.25 72 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.51) D. RUNOFF COEFFICIENTS I. Table 12 and Table 13 provide runoff coefficients. Steeply sloped areas and less frequent, higher intensity storms require the use of higher coefficients because infiltration and other losses have a proportionally smaller effect on runoff. Table 12 - Recommended Coefficient of Runoff for Pervious Surfaces by Selected Hydrologic Soil Groupings and Slope Ranges P] Slope A B C D Flat (0-1 %) 0.07 0.10 0.14 0.18 Average (2 - 6%) 0.12 0.15 0.19 0.23 Steep (Over 6%) 0.16 0.21 0.27 0.33 1 Source: MDT Hydraulic Manual -Chapter 7 73 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.513 Table 13 - Recommended Coefficient of Runoff Values for Various Selected Land Uses III Categorized by Surface Runoff Coefficients Forest 0.13 Asphalt 0.90 Brick 0.80 Concrete 0.90 Gravel 0.80 Roofs 0.85 Lawns, well drained sand soil Up to 2% slope 0.075 2% to 7% sloe 0.13 Over 7% sloe 0.18 Lawns, poor drained(cla soil Up to 2% slope 0.15 2% to 7% slope 0.20 Over 7% sloe 0.30 Categorized by Use Runoff Coefficients Driveways, walkways 0.80 Unimproved 0.20 Parks 0.18 Cemeteries 0.18 Railroad yards 0.28 Playgrounds 0.30 Business districts Runoff Coefficients Neighborhood 0.60 City (business/downtown) 0.83 Residential Single family 0.4 Multiplexes 0.55 Suburban 0.33 Apartment, Condominiums 0.60 Industrial Light 0.65 Heavy 0.75 1 Source: MDT Hydraulic Manual and Civil Engineering Reference Manual 74 CHAPTER 4 — STORMWATER DESIGN SECTION 4.5.5E E. TIME OF CONCENTRATION I. The travel time, the time required for flow to move through a flow segment, shall be computed for each flow segment. The time of concentration is equal to the sum of the travel times for all flow segments. Refer to the procedure described in Section 4.5.3G for equations and calculation methods. II. The time of concentration shall not be less than 5 minutes. For a few drainage areas, the time of concentration that produces the largest amount of runoff is less than the time of concentration for the entire basin. This can occur when two or more basins have dramatically different types of cover. The most common case would be a large paved area together with a long narrow strip of natural area. In this case, the engineer shall check the runoff produced by the paved area alone to determine if this scenario would cause a greater peak runoff rate than the peak runoff rate produced when both land segments are contributing flow. The scenario that produces the greatest runoff shall be used, even if the entire basin is not contributing flow to this runoff rate. F. INTENSITY I. The rainfall intensity (I) is the average rainfall rate in/hr for duration equal to the time of concentration for a selected return period. Once a particular return period has been selected for design and a time of concentration calculated for the drainage area, the rainfall intensity can be determined from Rainfall - Intensity tables. An example of such a table is given in AASHTO Model Drainage Manual, Chapter 7: figure 7-3; and in Appendix B (adopted by MDT). 4.6 WATER QUALITY TREATMENT DESIGN 4.6.1 INTRODUCTION A. Water quality treatment facilities are designed to remove pollutants contained in stormwater runoff. The pollutants of concern include sand, silt, and other suspended solids; metals such as copper, lead, and zinc; nutrients such as nitrogen and phosphorus; certain bacteria and viruses; and organics such as petroleum hydrocarbons and pesticides. The regulatory threshold or "trigger" for requiring compliance with this Basic Requirements is outlined in Section 4.2. B. The Water Quality design methods are formulated from the City of Kalispell Stormwater Quality Management Plan. This section presents a general description of the methodology for water quality design; refer to the Stormwater Quality Management Plan for more detailed descriptions. C. Many treatment facilities, when designed correctly, can function as both a water quality treatment facility and a flow control facility. This section describes design criteria for water quality treatment. Section 4.7 provides design criteria for flow control. All treatment facilities in new development and most redevelopment projects shall be on the ground surface. Underground treatment facilities are not permitted, except for those meeting minimum requirements of section 4.6.3I. 75 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3B II. Pretreatment a. Pretreatment is required for urban watersheds with more than 0.25 acres of impervious surface before the stormwater enters the infiltration facility: i Pretreatment volume shall be equal to 20% of WQv. The pretreatment volume is in addition to the infiltration basin's WQv sizing requirement. ii Pretreatment options are listed in section 4.6.3F.VIII. Bioretention square footages will be considered equal to infiltration square footages. III. Groundwater a. The bottom of the basins shall be at least 3 feet above the seasonal high groundwater table: The seasonal high water table shall be based on long-term piezometer records during at least one wet season or the mottled soil layer as determined by a licensed geologist, licensed engineer with geotechnical expertise, or hydrogeologist. IV. Access and Setbacks a. Minimum infiltration basin setback restrictions: i Building Foundations: At least 20 feet upstream and 50 feet downstream of infiltration basins; ii Back from top of slope greater than 15%: At least 50 feet or as determined by a licensed engineer with geotechnical expertise; iii Septic drain fields: At least 50 feet; iv Shallow water supply wells (typically individual homeowner wells): At least 100 feet; v Easement or property line: 20 feet; and, vi Floodplain: Outside 10-year High Water Level (HWL). b. Provide dedicated maintenance access route to infiltration basin from a public roadway. Access route shall be dedicated by maintenance easement or tract. V. Infiltration Criteria a. Short-term infiltration rate: The short-term soil infiltration rate shall be a minimum of 0.5 inches/hr and a maximum of 20 inches/hr. i Short-term infiltration rate determination: The requirements and procedures to conduct infiltration tests are described in Section 4.4; and, ii Reduction factors (RF): The reduction factor is applied to the measured short-term rate. A reduction factor of two (2) shall be used in determining the long-term infiltration rate below. 78 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.313 b. Long-term soil infiltration rate determination: The long-term infiltration rate is the estimated short-term rate with an applied reduction factor. The reduction factor is to account for measurement uncertainty, site variability, fluctuation of infiltration rate with water levels, pretreatment for total suspended solids (TSS) control and degree of maintenance that together affect long-term infiltration rates: i Long-term infiltration rate: Divide short-term rate by total reduction factor (RF) to determine the design long-term infiltration rate. C. An infiltration rate of 0.5 inches/hr to 2.5 inches/hr is typical for soil textures that possess sufficient physical and chemical properties for adequate treatment. When the Long-term infiltration rate is greater than 2.5 inches/hr a site specific analysis shall be performed to determine pollutant removal to prevent groundwater contamination. The maximum infiltration rates for the various soil types are outlined below in Table 14. The maximum rate used to calculate the design infiltration rate shall be the lesser of the values in Table 14 and the Long-term infiltration rate. Table 14 - Maximum Infiltration Rates for Soil Types Soil Texture Class Infiltration Rates Coarse sands, cobbles 20 Medium sand 8 Fine sand, loamy sand 2.4 Sandy loam 1 d. Infiltration basin drawdown time: Designed to drain dry within 72 hours after the design event using the long term soil infiltration rate: Infiltration basins will need to be refreshed and infiltration rate restored when the actual draw down time to drain dry exceeds 72 hours. VI. Planting Requirements a. Plant the basin with native vegetation containing a mixture of species of varying moisture tolerances. See Section 4.7 for planting guidelines. VII. Post Construction Verification a. Submit post -construction verification of volume and infiltration capacity: i Submit an as -built grading plan of the infiltration basin after construction to the City to verify the design storage volume has been provided; and, ii Perform post -construction testing of actual short-term infiltration rates to ensure the basin functions as designed or corrective action will need to be taken. Refer to APPENDIX B2. 79 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C C. WETPONDS I. Introduction a. A wet ponding basin is a basin that maintains a significant pool of water (wet pool or dead storage) between runoff events. The volume of the wet pool is the WQv. Refer to Section 4.6.2 to calculate the WQv. b. Peak flow control (detention) can be provided in the live storage area above the permanent pool. Figure 2 and Figure 3 illustrate a typical wetpond BMP. II. Wetpond Geometry a. The wetpool shall be divided into two cells separated by a berm. The first cell shall contain between 25 to 35 percent of the total wetpool volume. The berm volume shall not count as part of the total wetpool volume; b. Wetpond may be single cells when: i Wetpool volumes less than or equal to 4,000 cubic feet; and, ii Length to width ratio is > 4:1. C. Depth: i Sediment storage shall be provided in the first cell. The sediment storage shall have a minimum depth of 0.5 feet. The sediment storage volume shall not count as part of the total wetpool volume; ii Minimum average pool depth (below outlet elevation) at least 3 feet; and, iii Maximum pool depth (below outlet elevation) less than or equal to 8 feet. d. Length: i Promote residence time (length before water in basin is replaced with new inflow) within the basin and associated pollutant removal efficiency through the following; A) Design basins with a 3:1 length to width ratio or greater; and, B) Separate inlet pipes and outlet pipe to the greatest extent feasible to prevent "short circuiting" and promote "plug flow" through the basin. 80 Slopes: f Berms CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C Criteria for side slopes are given in Section 4.7.8D: A) 3 H: IV basin slope can be used in the wetpool area when the design conforms to the typical bench detail outlined in Figure 2; and, B) Grade basin slopes at 5:1 or shallower where infiltration or evaporation is expected to result in significant fluctuation in water levels during the summer months to improve aesthetics (avoid the dry bathtub look) and allow native vegetation to hide some of the water level fluctuation. A berm shall extend across the full width of the wetpool, and tie into the wetpool side slopes. If the berm embankments are greater than 4 feet in height, the berm must be constructed by excavating a key equal to 50 percent of the embankment cross sectional height and widths. This requirement may be modified if authorized by a geotechnical engineer based on specific site conditions; ii The top of the berm may extend to the WQv design water surface or be one foot below the WQv design water surface; and, iii If the top of berm is at the WQv design water surface, berm side slopes must be 3H: 1V. Berm side slope may be steeper (up to 2:1) if the berm is submerged one foot and is approved by a geotechnical engineer. 81 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C RawTERAecE 8 CY Class I Rip Rap (Not Required) SKUMR *u � !I•! SAMY / ACWTIC WWTATM XW" TWWAL SAS S.TE PRA7LE SIDE Am PRIi'A.S VUM V OF SK)SWR Yi El�r. MFMZT PM I _ TYPICAL BENCH DETAIL mm RMUN WITHIN 10' OF SKIMMER OUTLET NmKnxv= matcli (Not Required) �'wysAPTEr i AD6MTlC vEDEraTmR DENLTI IDQ w 2 V Pon 0,90 a—, 10- t B�------ta— "'--bears�rea TYPICAL BENCH DETAIL Figure 2 - Wetpond Details g. Outflow Control Structures Outlet structure shall be provided either as a manhole with a restrictor device or a skimmer in front of the outlet pipe. Refer to Section 4.7.4 for details of approved outflow structures; and, ii Dissipate flow energy and erosion potential at pipe outlets, typically using riprap. h. Groundwater i Wet ponds work best when the water already in the pond is moved out by incoming flows called "plug flow." Because treatment works on this displacement principle, the dead storage pool of wetponds may be provided below the ground water level without interfering unduly with treatment effectiveness. However, if combined with a detention function, the live storage must be above the seasonal high ground water level; and, ii Buffer the interaction between surface runoff and groundwater for those ponding basins excavated below the groundwater table. Install a liner of clay topsoil 1-foot thick along the basin bottom up to one foot above the outlet elevation as the buffer, if needed. 82 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C i. Planting Requirements Seed pond basin slopes with native seed mix containing a mixture of species of varying moisture tolerances. See Section 4.7.9 for planting guidelines. j. Access and Setbacks Minimum wet ponding basin setback restrictions: A) Back from top of slope greater than 15%: At least 50 feet or as determined by a licensed engineer with geotechnical expertise. ii Floodplain: Outside the 10-year High Water Level (HWL). A) Intent is to minimize routine flooding of basins and to avoid them from ending up as part of a stream if the channel meanders. iii Provide a dedicated maintenance access route to wetpond basin from the public roadway. Access route shall be dedicated by maintenance easement or drainage tract. k. Post Construction Verification Submit an as -built grading plan of the ponding basin after construction to the City verifying that the design water quality and flood control volumes have been provided. Design Considerations Wetpond treatment BMPs are not recommended for projects that discharge to trout bearing streams. Wetpond discharge could lower the temperature and decrease the Dissolved Oxygen level in the stream. 83 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C inlet pipe & catch basin per access road to inlet structure detention facility requirements tl r ,, tl r, I, FIRST WETPOOL CELL berm or baffle at design 255% to ?5% ,,f vc:;{)r5^ 4 I r r r WS or submerged 1' below design W.S. , Extend berm across entire i r wetpool width. berm top widthIf min. , II „ SECOND WETPOOL CELL , A WO design WS ; overflow WS wetpool width emergency overflow WS ; ; plantings required on cut B ; , slopes I 11 I' emergency spillway per detention facility requirements manhole & outlet pipe pie sized to pass peak flow per t r , conveyance requirements i i - access road to outlet erosion control & `J outlet structure energy dissipation per detention facility requirement B NOTE: Berm not required for ponds PLAN VIEW with length to width ratio > 4:1 or it volume less than 4000 c.t. NTS Figure 3 - Wet Pond Plan View 84 W41ROL ST*MTWZ EKROCKY avr*rLav Vs-* POND GVERFLM( S f IN 19 -14-11 P(" btSIGN WS - 10 Yp PA-04 NOW" SLOPt A6EYA71ON PER FACILITY REQUIREMENTS SLOE POPT T16N- NOTES; SEE DETENTION FACUTY REQUIREMENTS FOR LOCATION AND SETBACK REQUIREMENTS Figure 4 - Wet Pond Profiles CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3C Figure 6-3, Wet Pond Profife View -1 ow"m 'VP NTH OF WtM OVCWLDW SPILLVA7 \-VALVE KAY BE LOCATED INSIDE NON OR OUTSIDE WITH APPRUVED OPERATIONAL ACCESS iVITY MAIN HIM BIAICITCk SECTION A —A SITS nn7 cxu 37 M. TO LENGTH - 4 (k" x Im EMERMNT WWTATJON Rtoulpta POR WcTpOm DC"PIN, 3' OR L'CSS be" a, vm. MN ACCOUENDED m > a ry CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.2A 4.6.2 WATER QUALITY PROTECTION STANDARDS A. Stream and River Flow Control Standard I. The post development 10-year peak runoff rate shall be no greater than the pre - development 10-year, 24-hour peak runoff rate (based on SCS Type 1 unit hydrograph). II. The post development 100-year peak runoff rate shall be no greater than the pre -development 100-year, 24-hour peak runoff rate (based on SC Type 1 unit hydrograph). B. Wetland Standards I. An onsite wetland analysis is required for all new development. See Wetland Analysis in Section 4.3.3 Drainage Report; and, II. Flow control: See Wetland Flow Control Standards Chapter 6, in the Stormwater Qualily Management Plan. The Stormwater Quality Mana ement Plan can be obtained from the Kalispell Public Works Department. C. Water Quality Volume (WQv) Standard I. The water quality volume is the runoff from the first 0.5 inches of rainfall from a 24 hour storm using Arc III condition, or as otherwise required by the current MS4 Permit. 4.6.3 TREATMENT BMPS A. Introduction I. Infiltration swales/ponds, wet ponds, biofiltration swale, dry swales, and bioretention facilities can be effective in treating stormwater runoff. In most cases, soil properties must be appropriate to achieve effective treatment without adversely impacting groundwater resources. Mechanical treatment devices using hydrodynamic (vortex) technology can be used to physically separate petroleum products from stonmwater. This section provides design information and minimum requirements for all treatment BMPs identified in this manual. In most cases, treatment facilities can be combined with flow control facilities and shall meet all flow controls requirement in Section 4.7. All treatment BMP facilities shall be installed upstream of flow control facilities. II. Low Impact Development (LID) a. For new development and redevelopment projects requiring Water Quality Treatment the following LID practices shall be implemented, where practicable: i Infiltration of the Water Quality Volume ii Reuse the of Water Quality Volume b. If it is not practicable due to soil types, ground water elevation, or climate conditions to implement the LID practices the treatment BMPs listed in this section shall be used for Water Quality Treatment. 76 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3B III. Climate Conditions Designs a. The Kalispell area cold climate and warm summer periods can affect the performance and the long term maintenance requirements of flow control facilities and Treatment BMPs. b. For dry climates, designers should consider the following for each project: i Ensure that the permanent pool in wetpond designs can be maintained; ii Select landscaping plants for wet and drought weather; iii Use a surface layer of gravel instead of mulch. Mulch deteriorates fast and will need to be replaced more often; and, iv Use pretreatment cells or forebays to provide sedimentation due to the high rate of erosion and dust. C. For cold climates, designers should consider the following for each project: i Select salt -tolerant grasses, shrubs, and tree species to maintain vegetative cover; ii Use multiple cells and oversize the first pretreatment cell to account for high sedimentation rates; iii Avoid draining ponds during the spring, as temperature stratification and high chloride levels may discharge acidic or anoxic water downstream; iv Do not submerge inlet pipes into permanent pools to avoid causing pipe ice blockage; v Extend the soil filter media below the frost line; vi Slope pipes a minimum of 1 % or 2% to prevent standing water from freezing; vii Underdrains should be placed at least a foot below the frost line and increase the perforated pipe diameter by at least one pipe schedule. The minimum opening diameter hole for perforated pipes should be '/z inch; and, viii Consider snow storage in the design. B. INFILTRATION BASINS I. An infiltration basin is a practice that discharges surface water into the underlying soil. 77 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.31) D. BIOFILTRATION SWALES I. Introduction a. A biofiltration swale is an open, gently sloped, vegetated channel designed for treatment of stormwater. The primary pollutant removal mechanisms are filtration by grass blades which enhance sedimentation and trapping and adhesion of pollutants to the grass and thatch. II. Application and Limitations a. Biofiltration swales do not provide flow control but can convey treated runoff to flow control facilities.; b. Biofiltration swales shall be designed so that stormwater will flow evenly across the entire width of a densely vegetated area; C. Biofiltration swales shall be applied to small scale projects of 5 acres or less; d. Biofiltration swales shall not be located in shaded areas; e. Stormwater runoff carrying high concentration of oil and grease impairs the treatment capability of the swale; Oil control options shall be applied as pretreatment in this situation; f. Biofiltration swales shall be designed to be dry between storm events; and, g. The Swale shall not receive continuous base flows or be located in a high groundwater area. III. Groundwater a. The bottom of the basins shall be at least 3 feet above the seasonal high groundwater table: The seasonal high water table shall be based on long-term piezometer records during at least one wet season or the mottled soil layer as determined by a licensed geologist, licensed engineer with geotechnical expertise, or hydrogeologist. IV. Access and Setbacks a. Biofiltration swales shall meet the minimum setback requirements specified in 4.7.5B.III.a; and, b. Provide dedicated maintenance access route to the biofiltration swales from a public roadway. Access route to be dedicated by maintenance easement or tract. V. Biofiltration Design a. Design flows: The swale design is based on the Water Quality Design Flow (Qwq). The Qwq is calculated using the peak flow rate associated with the runoff Water Quality Volume of 0.5 Inches. See Section 6 for water quality protection standards; 86 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3D b. Swale Bottom Width: Determine the bottom width of the swale using Equation 14 or Equation 15; 2 1 Equation 14 n _ 1.486*A*R3*S2 'C n Where: Q = rate of flow (cfs); A = cross -sectional area of flow in the channel (square feet); R = hydraulic radius (feet); where R = A/P, P = wetted perimeter (feet); S = channel longitudinal slope (feet/foot); and, n = Manning's roughness coefficient (Table 9). C. For a trapezoidal channel with shallow flow, the hydraulic radius can be approximated to the depth of flow. Using this assumption, the following equation can be used to solve the required width: Equation 15 b = nWq*Qsg 1 — Zy 1.486*33*S2 Where: Q,q = rate of flow (cfs); y = depth of flow (feet) (4 inches max for sod); Z = side slope of the strip in the form Z:1; b = bottom width of strip (feet); S = channel slope (feet/foot); and, nWq = Manning's roughness coefficient for shallow flow conditions = 0.20 (unitless) 87 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3D d. To calculate design flow velocity through the swale; Equation 16 vwq = Q q A yy wq Where: A) VWq = design flow velocity (fps) B) Q,,,q = water quality rate of flow (cfs); C) A,q by + Zy2 = cross sectional area (sf) of flow at design depth; and D) Z = side slope of the strip per unit height (e.g., Z = 3 if side slopes are 3H:1 V). e. Calculate the length of the swale: The minimum channel length is 100 feet unless the width is increased per the minimum geometry requirements in the following minimum requirements. Use the following equation to determine the necessary Swale length to achieve a hydraulic residence time of at least 9 minutes (540 seconds). Equation 17 L = 540 * VWq Where: A) VWq = design flow velocity (fps); and, B) L = minimum allowable swale length (ft). VI. Minimum Requirements a. The biofiltration channel shall have a minimum length of 100 feet. The length shall not be reduced such that the minimum residence time and/or maximum flow depth criteria are violated; b. The maximum bottom width is 10 feet and the minimum width is 3 feet. If the calculated bottom width exceeds 10 feet, parallel biofiltration channels shall be used in conjunction with a device that splits the flow and directs an equal amount to each channel; C. The ideal cross-section is a trapezoid with side slopes no steeper than 3:1. However, a rectangular shape can be proposed if there are topographical constraints or other construction concerns; 88 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.31) d. Typically, the depth of flow shall not exceed 4 inches during the design storm. The depth of flow is 4 inches for sod and 3 inches for dryland grasses; e. The channel slope shall be at least 1 % and no greater than 5%. Slopes of 2% to 4% provide the best performance. When slopes less than 2% are used, an under -drain is required. A 6-inch-diameter perforated pipe shall be installed in a trench lined with filter fabric and filled with 5/8-inch minus round rocks. The pipe shall be placed at least 12 inches below the biofiltration channel bed and the bed shall incorporate topsoil that has a proportionately high sand content. See Figure 6; f. The maximum flow velocity through the swale under water quality design flow conditions shall not exceed 1 foot/second and the design shall provide for a 9 minute residence time; g. The maximum flow velocity through the swale under peak 100-year flow conditions shall not exceed 3 feet/second; and, h. A flow spreader shall be used at the inlet of a swale to dissipate energy and evenly spread runoff as sheet flow over the swale bottom. Flow spreaders are recommended at mid -length of the swale. For detail on flow spreaders see APPENDIX D. VII. Planting Requirements a. Grass shall be established throughout the entire treatment area of the Swale; b. Irrigation is required during the first summer following installation if seeding occurs in spring or summer; A newly constructed swale shall be protected from stormwater flow until grass has been established. This may be done by diverting flows or by covering the swale bottom with clear plastic until the grass is well rooted. If these actions are not feasible, an erosion control blanket shall be placed over the freshly applied seed mix; and, d. Swale treatment areas are subject to both dry and wet conditions, as well as accumulation of sediment and debris. A mixture of dry -area and wet area grass species that can continue to grow through silt deposits is most effective. A list of grass seed mixes is located in APPENDIX F. CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3D Figure 6-4 Boifiltration Swale Schematic maintenance acres$ road Inlet (modular grid pavemerA Porwas pay At, asphalt, ooncrele orgra*eli fod *veh*rAe access flaw spreader flow spreader roadway leno depends on (recommended � / N, j;,4swale area (see text) biotiltration swaie bottom {'min. swase length=1 00 ft-) Note: Longitudial slope 1-5% Provide underlain for slopes < 2% Figure 5 - Bioriltration Swale Schematic Figure 6-5 Boifiltration Swale Underdrain Detail Underdarin for slopes < 2% Filler fabm wrap m i nu in u m ad mended soil of qpp' sides and bottom IT",min. amended &pit min. ovef pq* perforalied ppe underdfain centered beream swede perforated on4leaAraki 1-1)riginal scd SECTION pipe cantered btrn�h sw-ale DETAIL A NTS W Onus clean drain rc�* filler fabric NOTE: Undordroin nwM infiltrate or drain `f(-.0ty 10 an acmptoble discharge point. Figure 6 - Bioriltration Swale Underdrain Detail for Slopes <2% Wo CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3E E. CONTINUOUS INFLOW BIOFILTRATION SWALES Introduction In situations where water enters a biofiltration swale continuously along the side slope rather than discretely at the head, a different design approach -the continuous inflow biofiltration swale-is needed. The basic Swale design is modified by increasing swale length to achieve an equivalent average residence time. For the most part, the specification listed in section 4.6.3D for Biofiltration Swales are the same for Continuous Inflow Biofiltration Swales except for the following modifications. II. Application and Limitations a. Continuous inflow swales are to be used when inflows are not concentrated such as locations along the shoulder of a road without curbs. This design may also be used when frequent small point flows enter a swale. In general, no inlet port should carry more than 10% of the flow; and, b. Continuous inflow swales shall not be used for a situation in which significant lateral point flow enters a swale at some point downstream from the head of the swale. III. Biofiltration Design a. The design flows from continuous inflow swales must include runoff from the pervious side slopes draining to the swale along the entire swale length; b. The method of analysis for continuous inflow swales is the same as for basin biofiltration swales (see 4.6.3D BIOFILTRATION SWALES) except for the following: The WQ design flow may be variable to reflect the increase in flow along the swale length. If only a single design flow is used, the flow at the outlet shall be used; and, ii Double the hydraulic residence time of a standard biofiltration swale so that it is a minimum of 18 minutes (1080 seconds). Equation 18 L = 1080 * V,Nq Where: Vwq = design flow velocity (fps); and, L = minimum allowable swale length (ft). 91 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F IV. Planting Requirements a. Interior side slopes above the WQ design treatment elevation shall be planted in grass. A typical lawn seed mix or the biofiltration seed mixes are acceptable. Landscape plants or ground covers other than grass shall not be used anywhere between the runoff inflow elevation and the bottom of the swale. F. BIORETENTION AREAS Introduction Bioretention areas are stormwater quality BMPs that capture and temporarily pond the water quality volume (WQv) in shallow basins or landscaped areas. The WQv is then rapidly filtered through a filter bed material to remove pollutants from stormwater runoff. The filtered runoff is typically collected and returned to the down gradient conveyance system, though it can also infiltrate into the surrounding soil in areas with permeable soils and low ground water. b. Bioretention areas are also known as "rain gardens" when used on individual residential lots, often without an underdrain. Bioretention creates a good environment for runoff reduction, filtration, biological uptake, microbial activity, and provides high pollutant removal. Three scales of bioretention systems, based on contribution drainage area (sf), are defined for this specification: i Micro-bioretention (250 to 2,500 sf); ii Small scale bioretention (2,500 to 20,000 sf); and, iii Bioretention basins (20,000 to 200,000 sf). II. Application and Limitations a. Bioretention systems shall not be designed to provide flow control. An overflow structure or a flow splitter structure shall be provided to convey flow from storms larger than the WQv to flow control facilities; b. Bioretention systems shall be applied to small-scale projects of 5 acres or less. Multiple filtering systems can be used for larger areas; C. Stormwater runoff carrying high concentration of oil and grease impairs the treatment capability. Oil control options shall be applied as pretreatment in this situation; d. Bioretention systems are susceptible to clogging by sediment and therefore pretreatment is a necessary part of the design; e. Bioretention systems should not receive continuous base flows or be located in a high groundwater area; and, ON CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F f. The minimum head or elevation difference needed at a site from the inflow to the outflow underdrain or pea gravel under -layer is typically 5 feet. III. Groundwater a. The bottom of the basins shall be at least 3 feet above the seasonal high groundwater table; i The seasonal high water table shall be based on long-term piezometer records during at least one wet season or the mottled soil layer as determined by a licensed geologist, licensed engineer with geotechnical expertise, or hydrogeologist. IV. Soils a. For bioretention areas placed in subsoils having a hydrologic soil group designation of B, C, or D, an underdrain system is required; and, b. Designs shall verify soil permeably by using on -site soils testing as outlined in Section 4. A soil testing is not required when an underdrain system is installed. V. Underdrains a. Underdrains shall be included in the design when subsoil infiltration rates are below 1.0 inch/hr; b. When an underdrain is required a minimum 6-inch-diameter perforated pipe shall be installed in a trench lined with filter fabric and filled with a foot depth of clean pea gravel; i The pipe spacing shall be at a maximum of 10 feet on center and a minimum grade of 0.5% must be maintained; and, ii A permeable filter fabric or sand layer shall be required between the gravel layer and the planting soil bed. C. All underdrain systems shall be day -lighted to an outfall structure. VI. Filter Media a. Planting soils media shall consist of a sandy loam, loamy sand, or loam texture per USDA textural triangle with a clay content ranging from 0 to 5%. In addition, the planting soil must have a 3 to 5% organic content. The recommended planting soil media mixture is: A) 85 — 88 % sand. (washed medium sand is sufficient) B) 8 - 12 % fines. (Includes both clay (max 5%) and silt C) 3 -5 % organic matter (leaf compost or peat moss) 93 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F ii Small scale bioretention and bioretention basin designs shall use premixed certified media from a vendor that meets the following requirements for phosphorus contend, cation exchange (CEC), and media filtration; A) The recommend P-index value is between 10-50; B) Soils with CECs exceeding 10 are preferred for pollutant removal; and, C) The medial should have an infiltration rate of 1 to 2 inches per hour iii Micro-bioretention (250 to 2,500 sf) soil media can be mixed on site; iv The minimum filter media depth shall be between 30 to 48 inches; and, v Filter media shall be placed in lifts of 12 to 18 inches. VII. Surface Cover a. Bioretention system shall have a 2 to 4 -inch landscape layer placed above the filter media to protect the soil bed from erosion. The landscape layers include the following: i Mulch: Mulch enhances plant survival, suppresses weed growth, and pre -treats runoff before it reached the filter media. Shredded, aged, hardwood bark mulch makes a very good surface cover; ii Turf grasses; Turf grasses (fine fescue, tall fescue) are typical used for micro bioretention applications such as front yards; and, iii River stone or pea gravel: Stone or gravel are not recommended in parking lot application since the increase soil temperatures and have low water holding capacity. VIII. Pretreatment a. Pretreatment of runoff entering the bioretention area is required to trap coarse sediment particles before they reach the filter bed. Pretreatment measures shall be designed to evenly spread runoff across the entire width of the bioretention area. Several pretreatment measures are feasible, such as: a grass filter strip below a flow spreader, a grass channel, or a pea gravel diaphragm. The following are approved pretreatment options; Micro-bioretention (250 to 2,500 sf): A) A grass filter strip extending a minimum of 10 ft from the edge of pavement and a maximum slope of 5%. 01 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F ii Small scale bioretention (2,500 to 20,000 sf): A) A grass filter strip with a pea gravel diaphragm or other flow spreader. The required length of the filter strip depends on the drainage area, imperviousness, and the filter strip slope. Design guidance on filter strips for pretreatment can be found in APPENDIX E; B) A grass channel with a pea gravel diaphragm or other flow spreader. The length of the grass channel depends on the drainage area, land use, and channel slope. The minimum grassed channel length shall be 20 feet. Design guidance on grass channels for pretreatment can be found in APPENDIX E; and, C) A Pretreatment Cell, see the description below. iii Bioretention basins (20,000 to 200,000 sf): A) A Pretreatment Cell, similar to a forebay, is located at the piped inlets or curb cuts leading to the bioretention area and has a storage volume equivalent to at least 15% of the total WQv. The design shall have a 2:1 length to width ratio. The cell can be formed by a wooden or stone dam or rock berm. IX. Design Method Criteria a. Pondin. Area: The ponding area provides for surface storage of stormwater runoff before it filters through the filter bed. The ponding area shall contain the entire volume associated with the runoff Water Quality Volume of 0.5 Inches. The ponding depth shall be designed to be 6 to 12 inches above the filter bed; and, b. Filtering Treatment Criteria: The filtering bed shall have a minimum depth of 30"; i The planting soil filter bed shall be sized using a Darcy's Law equation with a filter bed drain time of 48 hours and a coefficient of permeability (k) of 0.5 ft/day. ii The required filter bed area (Af) is computed using the following equation: Equation 19 Af = (Vwg*df)k*(hf+df)*tf Where: Af = surface area of filter bed (ft2); VW9 = water quality volume (ft3); df= filter bed depth (ft); k = coefficient of permeability of filter media (ft/day); hf= average height of water above filter bed (ft); and, tf = design filter bed drain time (days). 95 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F X. Minimum Requirements a. The filter bed surface should generally be flat so the bioretention areas fill up like a bathtub; b. Do not use heavy equipment in the bioretention basin; C. Observation wells and cleanout pipes should be included in the design if their contributing drain area exceeds 1 acre. The well should be tied into any T's or Y's in the underdrain system, and should extend upward to be flush with the surface and with a vented cap; and, d. Bioretention areas can be used for snow storage as long as an overflow is provided and they are planted with salt tolerant, non -woody plant species. Tree and shrub locations cannot conflict with plowing and piling of snow into storage areas. XI. Access and Setbacks a. Bioretention systems shall meet the minimum setback requirements specified in 4.7.513.III; and, b. Provide dedicated maintenance access route to the facility from a public roadway. Access route to be dedicated by maintenance easement or tract. XII. Planting Requirements a. A dense vegetative cover shall be established over the contributing drainage area before runoff can be accepted into the facility; b. A landscape plan shall be provided for the bioretention area in the drainage report; C. Surface sand filter layers shall have a grass cover to aid in pollutant adsorption. The grass should be capable of withstanding frequent periods of inundation and drought; d. The filter media soil bed shall be at least 4 feet in depth when trees are planted in the bioretention area but can be a minimum of 2.5 feet deep in facilities that will utilize plants other than trees; e. Planting recommendations for bioretention facilities can be found at the Montana Natural Resource Conservation web site at http://www.mt.nres.usda.gov. It is highly recommended that the planting plan be prepared by a qualified landscape architect; i Native plant species should be specified over non-native species; ii A selection of trees with an understory of shrubs and herbaceous material should be provided; iii Woody vegetation should not be specified at inflow locations; iv Trees should be planted primarily along the perimeter of the facility; 96 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F v Plants should be selected based on specified zone of hydric tolerance and must be capable of surviving both wet and dry conditions; and, vi "Wet footed" species should be planted near the center, whereas upland species are better near the edge. XIII. Maintenance Criteria a. The maintenance access shall be designed such that all areas of the bioretention area can be easily accessed, and shall be designed to allow vehicles to turn around; b. A maintenance right-of-way or easement shall be provided from a driveway, public or private road. The maintenance access shall have a minimum unobstructed drive appropriately stabilized to withstand maintenance equipment and vehicles; C. Maintenance for bioretention areas shall meet the requirements set in Section 4.10; and, d. Successful establishments of bioretention areas requires certain tasks be undertaken in the first year; i Initial inspections: For the first six months following construction, the site should be inspected a least twice after storm events that exceed a half —inch; ii Spot Reseeding: Inspector should look for bare or eroding areas in the contributing drainage or around the bioretention area, and make sure that they are immediately stabilized; iii Fertilization: One-time, spot fertilization may be needed for initial plantings; iv Watering: Watering is needed once a week during the first two months, and then as needed during the first growing season, depending on rainfall; and, v Remove and replace dead plants: Since up to 10% of plant stock may die off in the first year, construction contracts should include a care and replacement warranty to ensure vegetation is properly established and survives during the first growing season following construction. 97 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F PARKING LOT SHEET FLOW CURB STOPS I i i I i SAND DIAPHRAGM 10 "1 1 - . . I '. -.- . 4 1 1 - 1 1 _,,� � _j GRASS FILTER STRIP 1 4, 4,A I +,l 4 -1 1, I'A A II I I I .!, -4 1, 1 'T I I 1 4, 4 4 4, A 4, -4, A -1 -4 1, •1- ; +,k 1-4, -4, 4-4, t, t- 1, 1, A- I I I I -I I A 4 4- I 1I I 1- 1, 4 A 4-1 4 1 4 '1411,41'.4 •1 +'l + 1,14 -4 4 4 4 AA -1 + 1' -4 + + 11 -1 A -A 1 + 4 1 11 . �f I I I I -4 -1 4 1-1 j 11A A- -1 +1 1- 1 1 1 4 A � 1A I A A 4 1 1 4-44 4 1 4 -1 +4 1 J, I I I ,1..4 4 4 4 4 1 1 1, 1� I 1. ^1 1 r1 1 1 1 1 1- t A 4 1 4 4 1 1, t 1 .4 .1 j/ 1_4 I -i -f g.4 -4, OUTLET hi lull OVERFLOW BERM -CATCH BASIN" UNDERDRAIN COLLECTION SYSTEM PLAN VIEW e, PONDIN 2'- 3-MULCH 2.5' FTI TFIR M e-PER FOR, PIPE IN 9 G J40KET Figure 7 - Bioretention Area 98 ziw� + Lp—ir toy u1ir TO RECEIVING WATERS. Mmo LP-'2. -4- +UPE TC ol� 'DRAIN WQv-6" — 12" PONDING DEPTH OVERFLOW. BYPASS - FLOW PATH VEGETATED PRETREATMENTi 6: IA IN. DROP CURBINTAKE 94*111 12'SAND BED PEA GRAVEL —UNDERDRAIN SYSTEM CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3F BIORETENTION AREA VEGETATED PRETREATMENT (GRASSED SWAI E) PEA GRAVEL DIAPHRAGM (Z x 1'x CURB SLOT WIDTH) SLOPE To DRAIN MAX. PONDING LIMIT (UNUSABLE PARKING STALLS) —SLOTTED CURB, SIZED TO PASS: 0 peak FROM WOV (= 1.5'.1 MP. ACRE) MAX. PONDING DEPTH = 6- -777�— OVERFLOW -T 'BYPASS" —A 2'x VPEA GRAVEL DIAPHRAGM (FOR INLF=TPROTE-CTlOt4,'PRF=TREATMENT-.) Figure 8 - Bioretention Area Off-line Schematic M CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G G. DRY SWALES I. Introduction a. Dry swales are essentially shallow bioretention cells that are configured as a linear channel. The dry swale is a vegetated conveyance channel designed to include a filter bed of prepared soil that overlays an underdrain system. Dry swales are sized to allow the entire WQv to be filtered or infiltrated through the bottom of the swale. The filtered runoff is typically collected in an underdrain and returned to the down gradient conveyance system, though it can also infiltrate into the surrounding soil in areas with permeable soils and low ground water. Dry swales are well suited to treat highway or low and medium density residential road runoff and along margins of small parking lots. II. Application and Limitations a. Dry swales shall not be designed to provide flow control. Dry swales are an on-line practice and must be designed with enough capacity to convey runoff for the peak 10-year and 100-year storm events and be non -erosive for the peak 2-year storm event. An overflow structure or a flow splitter structure can be provided to convey flow from storms larger than the WQv to flow control facilities; b. Dry swales shall be used on sites with longitudinal slopes of less than 4%; C. Dry swale systems shall be applied to small-scale projects of 5 acres or less; d. Stormwater runoff carrying high concentrations of oil and grease impairs the treatment capability. Oil control options shall be applied as pretreatment in this situation; e. Dry swale systems are susceptible to clogging by sediment and therefore pretreatment is a necessary part of the design; f. Dry swales shall be designed so that stormwater will flow evenly across the entire width of a densely vegetated area; g. Dry swales should not receive continuous base flows or be located in a high groundwater area; and, h. The minimum head or elevation difference needed at a site from the inflow to the outflow underdrain or pea gravel under -layer is typically 3 to 5 feet. III. Groundwater The bottom of the basins shall be at least 3 feet above the seasonal high groundwater table: The seasonal high water table shall be based on long-term piezometer records during at least one wet season or the mottled soil layer as determined by a licensed geologist, licensed engineer with geotechnical expertise, or hydrogeologist. 100 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G IV. Soils a. For dry swales placed in subsoils having a hydrologic soil group designation of B, C, or D, an underdrain system is required; and, b. Designs shall verify soil permeably by using on -site soils testing outline in Section 4. A soil testing is not required when an underdrain system is installed. V. Underdrains a. Underdrains shall be included in the design when subsoil infiltration rates are below 1.0 inch/hr; b. When an underdrain is required a minimum 6-inch-diameter perforated pipe shall be installed in a trench lined with filter fabric and filled with a foot depth of clean pea gravel; i The pipe spacing shall be at a maximum of 10 feet on center and a minimum grade of 0.5% must be maintained; and, ii A permeable filter fabric or sand layer shall be required between the gravel layer and the planting soil bed. C. All underdrain systems shall be day lighted to an outfall structure. VI. Filter Media a. The recommended planting soil media mixture is: i 85 — 88 % sand. (washed medium sand is sufficient); ii 8 - 12 % fines. (Includes both clay (max 5%) and silt; and, iii 3 -5 % organic matter (leaf compost or peat moss); b. Designs shall use certified media mixed from a vendor that meets the following requirements for phosphorus content, cation exchange (CEC), and media filtration: i The recommended P-index value is between 10-50; ii Soils with CECs exceeding 10 are preferred for pollutant removal; and, iii The media should have an infiltration rate of 1 to 2 inches per hour; C. The minimum filter media depth shall be between 24 to 48 inches; and, d. Filter media shall be placed in lifts of 12 to 18 inches. 101 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G VIL Pretreatment a. Pretreatment of runoff entering the dry Swale is required to trap coarse sediment particles before they reach the filter bed. Pretreatment measures shall be designed to evenly spread runoff across the channel bottom width of the dry swale. Sheet flow: A grass filter strip with a pea gravel diaphragm or other flow spreader. The required length of the filter strip depends on the drainage area, imperviousness, and the filter strip slope. Design guidance on filter strips for pretreatment can be found in APPENDIX E; and, ii Channel flow: A Pretreatment Cell, similar to a forebay, is located at the piped inlets or curb cuts leading to the dry swale and has a storage volume equivalent to at least 15% of the total WQv. The design shall have a 2:1 length to width ratio. The cell can be formed by a wooden or stone dam or rock berm. VIII. Design Method Criteria a. Shape: The swale shall have a trapezoidal or parabolic cross section with side slopes of 3:1 or flatter. Flatter slopes are encouraged where space is available; b. Bottom Width: The swale bottom width shall range from 4 to 8 feet; C. Longitudinal Slope: The slope of the Swale shall be between 1 % and 4%. 1% and 2% are recommended to permit temporary ponding of the WQv within the channel. The grade should be continuous and uniform; d. Ponding Depth: Drop structures or check dams can be used to create ponding cells along the length of the swale. The maximum ponding depth in a swale shall not exceed 18" at the most downstream point. The average ponding depth throughout the swale should be no deeper than 12 inches. The swale ponding area provides for surface storage of stormwater runoff before it filters through the filter bed. The Swale ponding area shall contain the entire volume associated with the runoff Water Quality Volume of 0.5 Inches; e. Check Dams: Drop structures or check dams shall be spaced based on the channel slope and ponding requirement. Check dams must be firmly anchored into the side -slopes to prevent outflanking and be stable during the 10-year and 100-year storm events. The height of the check dam should not exceed 18 inches. Armoring may be needed behind the check dam to prevent erosion, and shall be designed to spread runoff evenly over its surface; 102 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G f. Drawdown Time: Dry swales shall be designed so that the water quality treatment volume is completely filtered within 24 hours or less. The drawdown time can be achieved by using a sandy soil mix along with an underdrain system; g. Filtering Treatment Criteria: The filtering bed shall have a minimum depth of 24"; The soil filter bed shall be sized using a Darcy's Law equation with a filter bed drain time of 24 hours and a coefficient of permeability (k) of 0.5 ft/day; and, ii The required filter bed area (Af) is computed using Equation 19. h. Conveyance and Overflow: Dry swales shall be designed with dimensions and slopes such that a velocity of 3 feet per second will not be exceeded for the 0.5 inch rain event. The swale shall convey the 10-year and 2-year storm events at non -erosive velocities with at least 6 inches of freeboard. IX. Minimum Requirements i Inlet to dry swales shall include energy dissipaters, such as rip rap; ii Do not use heavy equipment in the dry swale; and, iii Dry swales can be used for snow storage as long as an overflow is provided and they are planted with salt tolerant, non -woody plant species. Tree and shrub locations cannot conflict with plowing and piling of snow into storage areas. X. Access and Setbacks a. Bioretention systems shall meet the minimum setback requirements specified in Section 7; and, b. Provide dedicated maintenance access route to the facility from a public roadway. Access route to be dedicated by maintenance easement or tract. XI. Surface Cover and Planting Requirements a. Dry swales system shall have a 3 to 4 -inch landscape layer placed above the filter media to protect the soil bed from erosion. The landscape layers include the following: i Turf Grasses: Turf grasses that require minimal maintenance shall be used in dry swales. Native grasses are preferred, but not required. Salt tolerant grass species should be chosen for dry swale application along roads. Grasses must be capable of surviving both wet and dry conditions; and, ii River Stone or Pea Gravel: Stone or gravel are not recommended in parking lot application since the increase soil temperatures and have low water holding capacity. 103 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G b. A dense vegetative cover shall be established over the contributing drainage area before runoff can be accepted into the facility; C. A landscape plan shall be provided for the dry Swale in the drainage report; and, d. It is highly recommended that the planting plan be prepared by a qualified landscape architect. XII. Maintenance Criteria a. The maintenance access shall be designed such that all areas of the dry swale can be easily accessed, and shall be designed to allow vehicles to turn around; b. A maintenance right-of-way or easement shall be provided from a driveway, public or private road. The maintenance access shall have a minimum unobstructed drive appropriately stabilized to withstand maintenance equipment and vehicles; C. Maintenance for dry swales shall meet the requirements set in Section 4.10: d. Successful establishments of dry swales requires annual inspections to trigger maintenance; i mot Reseeding_ Inspector should look for bare or eroding areas in the contributing drainage or around the dry swale area, and make sure that they are immediately stabilized; ii Fertilization: One-time, spot fertilization may be need for initial plantings; iii Remove any accumulated sediment deposits on the filter bed surface or in the pretreatment cells; and, iv Inspect side slopes and grass filter strips for evidence of any rill or gully erosion and repair. 104 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3G ROT -OM �'.,;DTH 0, yr 2 '(EAR -LVF- %VQv LEVEL 2.5 vN. VAN G;AVEL, G' !ND ; DRa PER,GRIDF— A-H-11 PI / DRY SWALE CROSS SECTION, NTS Figure 9 - Dry Swale Cross Section RIPRAP 6" UNI)ER DRAA OUTFAt!- j,--PRLTREATMf-NT !FCRLBAY) P�E PE PR0TEC'k3N --- f- CU-FALL I STRUC -UR- . ..... - ------ NFLOW oull, I 1)w ------------ CHE-�'K DAM DRY SWALE PLAN VIEW NTS Figure 10 - Dry Swale Plan View =RETRZ-A-VENT (PORE9V) 6" PERFORATE,--) 6" MIN. r-Rr---B0ARD FABRIC :Y MIN, 0JTFALL STRUCT,)RIF PRY SWALt f!RQI7IL91.NTq Figure 11 - Dry Swale Profile 105 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.3H H. WETLANDS I. A wetland analysis is required for all new development and redevelopment. A wetland checklist, located in APPENDIX A is required to be completed and submitted with the drainage report. The Wetland checklist helps to identify if wetland resources may be present and further wetland assessment is required. If you check "yes" for any wetland indicators on the checklist, a Wetland Assessment outlined in the Kalispell Stormwater Quality Management Plan is required. The assessment must be performed by a wetland professional trained and familiar with the current US Army Corps of Engineers Regional Supplements for Wetland Delineations and the most recent Army Corps of Engineers guidance for Jurisdictional Determinations. Refer to City of Kalispell Stormwater Quality Management Plan for additional details. The Stormwater Quality Management Plan can be obtained from the Kalispell Public Works Department. II. In rare instances, wetlands can be used for water quality treatment. Protection strategies in the table below have been developed to protect wetlands from changes to their hydrology, plant diversity, function and water quality. An on - site wetland assessment is required to determine the stormwater management classification for each wetland. Refer to Stormwater Quality Management Plan Chapter 3.4 for the procedure on how to use Table 15. Table 15 - Wetland Protection Standardslll (Stormwater Quality Management Plan) Stormwater Management Bounce Limit (2- Inundation Period (2-yr Water Quality (WQ) Classification 1 yr Storm Event)131 Storm Event)141 Pretreatmentlel Maintain existing Maintain existing Preserve hydrologic conditions hydrologic conditions Implement WQ standards prior (historical if hydrology has (historical if hydrology has to discharge into wetland recently changed) recently changed) Existing hydrologic Existing hydrologic Implement WQ standards prior Manage 1 conditions plus 0.5 foot conditions plus 1 day to discharge into wetland increase allowed increase allowed Manage 2 Existing hydrologic conditions plus 1 foot Existing hydrologic Implement WQ standards prior increase allowed conditions or longer to discharge into wetland Existing hydrologic Existing hydrologic Sedimentation basin (15 CY Manage 3 conditions or higher conditions or longer storage volume perimpervious acre of watershed) 1 Adapted from Minnesota Storm -Water Advisory Group, 1997 & MnBWSR, 2004 2 Management Classification as determined by field inventory and ranking methodology outlined in Appendix A or current version. 3 Height between typical water level and 2-year high water level (HWL). 4 Inundation period begins with the storm event and ends when water levels drop back to within 0.5 feet above the typical water level. 5 Pretreatment of urban runoff before entering wetland 6 Wetland may be used to meet water quality volume (WQ„) BMP standards with a sedimentation basin upstream of wetland to collect coarse sediment or other upstream permitting requirements ifmore restrictive 106 CHAPTER 4 — STORMWATER DESIGN SECTION 4.6.31 EMERGING TECHNOLOGIES AND MECHANICAL TREATMENT I. Emerging technologies and mechanical treatment devices include but are not limited systems that treat stormwater through filtration, settling, absorption, adsorption, or a combination of these mechanisms. Mechanical treatment can be used when Low Impact Development practices are shown to not be feasible for the site. Mechanical treatment devices must be capable of removing at least 80% of the long term influent Total Suspended Solids (TSS) as demonstrated in full scale field testing following the multi -state endorsed Technology Acceptance Protocol — Ecology (TAPE). Independent proof of 80% TSS removal performance must be submitted in the form of a verification letter from a Technology Acceptance and Reciprocity Partnership (TARP) participating state or a General Use Designation by the Washington State Department of Ecology. II. When sizing a mechanical treatment device for the water quality flow rate, use Equation 9 to calculate the peak discharge (qp). III. The City Engineer reserves the right to deny the use of any emerging technologies and mechanical treatment systems even if it has been approved by Ecology. The City shall consider the following as they make decisions regarding the use of new stormwater technologies: a. Remember the oal: The goal of any stormwater management program or BMP is to treat and release stormwater in a manner that does not harm beneficial uses. Treatment performance objectives are listed in the Stormwater Qualms Management Plan. b. Exercise reasonable caution: An emerging technology shall not be considered for use for new development sites unless there are strong supporting data indicating that its performance is expected to be reasonably equivalent to the BMPs already approved by the City. 4.7 FLOW CONTROL 4.7.1 INTRODUCTION A. This Section outlines the requirements for sizing flow control facilities. Standard flow control facilities are detention, retention (natural depressions), and infiltration facility. Any other facility is considered a non-standard system, and shall be evaluated individually by the City Engineer. Flow control facilities are necessary to mitigate potential adverse impacts on down -gradient properties due to the increase in stormwater runoff caused by land development. B. The peak rate of stormwater runoff from any proposed land development to any natural or constructed point of discharge downstream shall not exceed the pre - development peak rate of runoff. The post development volume of runoff can exceed the pre -development volume of runoff when the required down -gradient analysis demonstrates that there will be no adverse impacts on down gradient properties or existing natural and constructed conveyance systems. Refer to Section 4.10 for maintenance requirements. 107 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.2A 4.7.2 APPLICABILITY A. All projects meeting the regulatory threshold outlined in Section 4.2.1 C shall comply with this Basic Requirement. 4.7.3 DETENTION FACILITIES A. Introduction A detention system is a storage facility that has a surface discharge. A detention facility is intended to control peak stormwater runoff rates but may not control volume. II. Minimum Requirements. The following minimum requirements shall be met. Additional requirements are specified in Section 4.7.8. Discharge Rates i Detention facilities shall be designed such that the release rate does not exceed the pre -developed conditions for various storm events. The analysis of various design storms is needed to control and attenuate flows from both low and high frequency storm events. ii The total post -developed discharge rate leaving the site shall be limited to the pre -development rates outlined in Table 4. By-pass flow shall be discharged at the pre -developed flow rate. Bypass flow is the runoff that leaves the site without being conveyed through the new development or redevelopment drainage system. iii If the detention facility is also proposed to function in conjunction with a water quality treatment facility, the following criteria must be met: A) The first orifice or outlet from the facility must be placed a minimum 6 inches above the pond bottom; and, B) Infiltration rate shall be verified by methods outlined in 4.4.313.III. Table 16 - Allowable Discharge Rates Design Frequency (Type 1 - 24-hr storm) Post -Developed Discharge Rate[ 1] 10-year < 10-year pre -developed 100-year < 100-year pre -developed 100-yearl2l (Emergency Overflow) >_ 100-year post -developed. Overflow route only 1 Post -developed flow is equal to the release from detention facility plus the bypass flow. 2 The emergency overflow shall direct the 100-year post -developed flow safely towards the downstream conveyance system. 108 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4A b. Facility Volume The NRCS Type 1 24-hour storm events are the design storms to be used for all flow control facilities that use a surface discharge. The design water surface for all facilities shall be the 100-year post developed water surface elevation. All overflows (structure or spillway) shall be located above the design water surface elevation and pass the 100-year 24-hr post developed peak flow rate. Setbacks When a detention facility is proposed upslope of developed property or at the top of a slope inclined 15% or greater, the minimum setback from the slope must be greater than or equal to 50 feet or as determined by a licensed engineer with geotechnical experience. The distance between the outlet structure and the inlet into the detention facility shall be maximized. d. Release Point Stormwater runoff from a developed site shall leave the site in the same manner and location as it did in the pre -developed condition. Therefore, a detention system may be used only when a well- defined drainage conveyance system is present prior to development. 4.7.4 OUTFLOW CONTROL STRUCTURES A. Introduction Control structures are manholes or catch basins with a restrictor device used for controlling outflow from a facility to meet a desired standard. Outflow structures are required for all stormwater detention facilities. The restrictor device is usually multiple orifices, consisting of two or more orifices and/or a weir section sized to meet performance requirements. This section presents a general overview of flow control structures. 109 100-YR 24-HR POST -DEVELOPMENT W.S. ELEVATION 10-YR 24-HR POST -DEVELOPMENT W.S. ELEVATION 6" ABOVE POND BOTTOM CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4A 100-YR MINUS 10-YR PRE -DEVELOPMENT FLOWRATE -YR DEVELOPMENT )WRATE Figure 12 - Example Outflow Control Structure 110 CHAPTER 4 - STORMWATER DESIGN SECTION 4.7.4A II. Runoff shall enter the detention facility through a conveyance system separate from the control and outflow conveyance system. The distance between the inlet and outlet shall be maximized to reduce sediment from accumulating in the outflow structure. FIGURE 7-1, TYPICAL DETENTION POND OUTLET SECTION NTS CONTROL S EMERGENCY OVERFLOW WC g, POND OVERFLOW WS 100 YR P4-HR POND DESIGN WS u In YR P4-HP MIN. 6" �,.--•"'r-- SEOIMENT STORAGE 2' EMBANKMENT JOP WIDTH OF BERM EMERGENCY? OVERFLOW SPILLWAY EMERGENCY OVERFLOW SPILLWAY CROSS SECTION NTS TOP WIDTH OF SPILLWAY EMERGENCY OVERFLOW WS _ POND OVERFLOW WS s I00 YR 74-HR POND DESIGN WS 2 10 YR 24-dB OCK LINING OMPACTED EMBANKMENT EMERGENCY OVERFLOW SPILLWAY CROSS SECTION NTS EMERGENCY OVERFLOW WATER SURFACE n 2' MIN. POND OVERFLOW WS—4 100 i' WELL GRADED ROCK UNING ARMOR ARMOR WITH COVER, NTS 2 IDO YR 94—HR 1a4 ,.i, .......___.. • _ °GRASS AND TOP SOIL �i' WELL GRADED ROCK LINING NOTES: THE ARMORING MAY HAVE A 4' COVER OF TOPSOIL AND GRASS Figure 13 - Detention Facility Outflows 111 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.413 B. OUTFLOW CONTROL STRUCTURE TYPES I. Multiple Orifice Restrictors a. In most cases, a control structure needs only two orifices: one at the bottom and one near the top of the riser; b. Minimum orifice diameter is 3 inches; and, C. Orifice shall be constructed on a baffle (Figure 14) or on a tee section (Figure 15). II. Risers and Weir Restrictor a. Properly designed weirs maybe used as flow restrictors. However they must be designed to provide for primary overflow of the developed 100-year peak flow discharging to the detention facility; and, b. The combined orifice and riser (or weir) overflow may be used to meet flow requirements. However the design must still provide for primary overflow of the developed 100-year peak assuming all orifices are plugged. III. Skimmer a. A skimmer is used as a flow restrictor and traps floatable debris and petroleum product. A skimmer keeps the outlet pipe free of debris and reduces maintenance; b. Provide skimming up to the 10-year event high water level or greater; and, C. Design flow velocities thru the submerged skimmer opening at 1.5 fps or lower under the 10-year event high water level. See Figure 16 and Figure 17 for details. C. MINIMUM REQUIREMENTS. The following minimum requirements shall be met. Additional requirements are specified in Section 4.7.8. I. Access Requirements a. An access road to the control structure is required for inspection and maintenance, and shall be designed and constructed as specified in Section 10; and, b. Manhole and catch basin lids for control structure shall be locking and rim elevation shall match proposed finish grade. 112 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C Frames, grates and round solid covers marked "drain" with locking bolts. ///''' attach shear gate J control rod to support in j bracket on inside of 1' min. t' min. i rams grate a evatwn _ access opening under pavement per plans ; max w.s. G [DESIGN W.S. s= min. overflow conditions i �- elbow restrictors i4 . see detail below ''- .4 shear gate with handholds, i_� control rod for drain steps or ladder - flow orifice plate 10 gage 2; min. �j= alvanized galvanized steel with orifice — n diameter 1" minimum min. { _ less than diameter of ' concrete hole A t— SECTION A -A NTS PLAN VIEW NTS removable water -tight coupling i grouted 6" min, plate welded -f to elbow with \6"max. orifice as specified ELBOW RESTRICTOR DETAIL NTS SECTION B-B NTS ISOMETRIC NTS Notes: Metal parts: corrosinon resistant steel parts galvanized and asphalt coated Catch basin: 72" diameter, in accordance with AASHTO M-199 Orifice: sized and located as required with lowest orifice a minimum of 2' from base Figure 14 - Flow Restrictor Baffle 113 removable watertight coupling or flange CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C frame, grate & solid cover marked "DRAIN" with locking bolts min. 1 pa ement ts" max vertical bar 6" min. grate for T secondary inlet late welded to elbow---1 detail with orifice as specified elbow restrictor,see pipe supports I f I handholds. steps or ELBOW RESTRICTOR DETAIL see Note 6 -" ladder NTS 4.5 x D T T min. 2' min D 1 I outlet pqe see rotes t & 5 Inlet ' Pipe invert and elevation £ shear gate with control per plans CV 2" rod for cleanoutJdrain t' section of pipe t 2" (rod bent as required attached by gasketed = € for vertical alignment band to allow removal N 1 2" with cover) restrictor plate with orifice diameter as specified (not needed if SECTION A -A ISOMETRIC for spill control only) NTS NTS 2' min. clearance Notes: 1. Metal parts: corrosinon resistant. Non galvanized part preferred. Parts galvanized to have asphalt coated 2. Catch basin: minimum 54" diameter 3. Frame and ladder or steps offset so: A) Cleanout gate is visible from top, B) Climb -down space is clear of riser and ceanout gate 4. If metal outlet pipe connects to cement concrete pipe: outlet pip to have smooth O.D. equal to concrete pip I.D. less '/4". 5. Provide at least one 3" X .90 gage support bracket anchored to concrete wall. (maximum 3 ft vertical spacing) 6. Locate elbow restrictor (s) as necessary to provide minimum clearance as shown. / to any portion of frog-T including elbows A A t -1 s l tI i angle as 1 necessary ' see note 7 j ladder rungs elbow restrictor �r-,-2-rnin.see detail / PLAN VIEW NTS Figure 15 - Flow Restrictor (Tee) 114 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C 2"x6" KEYWAY CAST INTO WALL BY SUPPLIER BAFFLE WALL SHALL BE CAST A WITH STRUCTURE, KEYED INTO STRUCTURE, OR BE OTHERWISE CONSTRUCTED TO CREATE A WATER -TIGHT __ SEAL. XX" DIA. HOLE IN BAFFLE WALL XX" 0 HOLE CENTERED // RECTANGULAR) _ XXXX IN BAFFLE WALL SKIMMER ADDITIONAL4'S OPENING x4'-0" LONG FOR GRATE DESIGN A #4 0 12 SEE DETAIL HORIZONTAL HOLE FOR XX" RCP #4 ® 72" SKIMM R VERTICAL GRAT SECTION A -A CONCRETE BAFFLE WALL XX" DIA. HOLE IN BAFFLE WALL 1 RIM ELEV. XXXX' _ _ HOLE FOR XX" DIA. FLEV_= XXXX I OUTLET PIPE OUTLET ELFV. (BE) ELEV.= XXXX' 0.5' %> 4'(W) X i'(H) �-�--�-� MIN. OPENING 0.5' 1. 4 CY CLASS- 1" MINUS AGGREGATE t RIPRAP O 6" r CAI NOTES: 1, SEE STORM DRAWINGS/SCHEDULE FOR DESIGN ELEVATIONS. 2. CENTER SKIMMER ON O.E. CONTOUR AND GRADE IN FRONT OF SKIMMER OPENING AS NECESSARY TO PROVIDE FOR SKIMMER OPENING. 3. ANCHOR BOLTS SHALL BE STAINLESS STEEL (OR HOT DIPPED OALVANI2ED) WEDGE OR STRIKE ANCHORS, 3.5" MIN. LENGTH. 4. PREFABRICATED GALVANIZED SKIMMER GRATE, PLATE STYLE BY HAALA INDUSTRIES IS AN APPROVED EQUAL. (SEE HAALAINDUSTRIES.COM) STANDARD DETAILS PONOING BASIN SKIMMER STRUCTURE WITH CONCRETE BAFFLE WALL SKIMMER DIAMETER SKIMMER OPENING (wxH) 3' 2'x0.5 -0' 5' 4'x t' 6' S.5'x7.5' Figure 16 - Skimmer (with baffle wall) 115 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C /—PROVIDE 6-1/2 ANCHOR i BOLTS WITH CLIPS (1) 1 1/2%3/8" OUTER RING I I 1 1/2"x3/8" STEEL DIAMETER OPENING (wxH) Figure 17 - Skimmer 116 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C II. Methods of Analysis a. Figure 18 provides equations and coefficients for calculating flow through the most common types of weirs and orifices used for flow control. For additional information on weirs the engineer should consult a hydraulic reference. FLOW EQUATIONS FOR VARIOUS S IN EIR AND ORIFICE TYPES 'WeiriOrifice Type Equation � Sharp Crested V-notch D = C(Yan � Yz OMOti�•eirl Broad Crested Suppressed 0 = CLHY2 0.33 Rectangular ,,weir Rectangular Sharp Crested Weirs' Q=QL-0.2H)H 3.27+0.40 Contracted 1,- Suppressed 0 = CLHY2 Sharp Crested. Cipoletti jrapezoidail Q = GLH - 3.367 Side slopes are 1:4 Broad Crested Trapezoidal 'Weir 7 t:- 2 a X 7 =C�.�� n,9)H�" i LH —13 0,60 — t 3 , Orifice 0 = C.� "� 0.62 The weir inserts should be set above the pond bottom a height of at least hvice the =aximum bead. Q = floor (cfs); C = coefficient of discharge; -4 = area of orifice (square feet):, H = hydraulic head (feet); g = gravity (32.2 feet'secornd2): Q = angle of side slopes (degrees); Y= storage depth (,feet)- L = weir lenngdn or opening (feet) Figure 18 - Flow Equations for Various Weir and Orifice Types III. Risers Overflow a. Figure 19 can be used to determine the head (in feet) above a riser of given diameter and for a given flow (usually the 100-year peak flow for developed conditions). For additional information, consult a hydraulics reference. 117 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.4C 1 1 i a • I Figure 19 - Flow Rates vs. Head (riser) 118 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.5A 4.7.5 INFILTRATION FACILITIES A. Introduction I. An infiltration facility is used for disposing of stormwater runoff into the subsurface and can be used for flow control provided that: a. The discharge is uncontaminated or properly treated prior to the stormwater entering the infiltration facility; b. The Geotechnical Site Characterization demonstrates the suitability of the soil for subsurface disposal; and, C. The down -gradient analysis indicates that adverse impacts are not anticipated. II. The engineer shall consider the impact of infiltration on groundwater elevations both on site and on down -gradient properties. B. MINIMUM REQUIREMENTS (in addition to Section 4.7.8). Pretreatment Pretreatment is required for urban watersheds with more than 0.25 acres of impervious surface before the stormwater enters the infiltration facility; Pretreatment volume shall be equal to 20% of WQv. The pretreatment volume is in addition to the infiltration basin's WQv sizing requirement. II. Depth to Groundwater and Limiting Layer a. The base of the infiltration facility shall be > 5 feet above the limiting layer (bedrock, clay lens, etc.); and, b. The bottom of the basins shall be a least 3 feet above the seasonal high groundwater table. The seasonal high water table would be based on long-term piezometer records during at least one wet season or the mottled soil layer as determined by a licensed geologist, licensed engineer with geotechnical expertise, or hydrogeologist. III. Access and Setbacks a. Minimum infiltration facility setback restrictions: Building Foundations: Infiltration facility to be at least 50 feet up - slope and 20 feet down -slope from building foundation unless a reduction is geotechnically justified; ii Back from top of slope greater than 15%: At least 50 feet or as determined by a licensed engineer with geotechnical expertise; iii At least 200 feet from springs used for drinking water supplies; iv Septic drain fields: At least 100 feet; 119 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.513 v Shallow water supply wells (typically individual homeowner wells): At least 100 feet; vi Easement, external tracts or property line: 20 feet; and , vii Floodplain: Outside 10-year High Water Level (HWL). b. Provide dedicated maintenance access route to infiltration facility from a public roadway. Access route to be dedicated by maintenance easement or drainage parcel. IV. Infiltration Criteria. Short term infiltration rates shall be determined using the field methods presented in Section 4.4; a. Short-term infiltration rate: The short-term soil infiltration rate shall be a minimum of 0.5 inches/hr and a maximum of 20 inches/hr. i Short-term infiltration rate determination: The requirements and procedures to conduct infiltration tests are described in Section 4.4.313.II1; and, ii Reduction factors (RF): The reduction factor is applied to the measured short-term rate. A reduction factor of two (2) shall be used in determining the long-term infiltration rate below. b. Long-term soil infiltration rate determination: The long-term infiltration rate is the estimated short-term rate with an applied reduction factor. The reduction factor is to account for measurement uncertainty, site variability, fluctuation of infiltration rate with water levels, pretreatment for total suspended solids (TSS) control and degree of maintenance that together affect long-term infiltration rates: i Long-term infiltration rate: Divide short-term rate by total reduction factor (RF) to determine the design long-term infiltration rate. C. An infiltration rate of 0.5 inches/hr to 2.5 inches/hr is typical for soil textures that possess sufficient physical and chemical properties for adequate treatment. When the Long-term infiltration rate is greater than 2.5 inches/hr a site specific analysis shall be performed to determine pollutant removal to prevent groundwater contamination. The maximum infiltration rates for the various soil types are outlined in Table 14. The maximum rate used to calculate the design infiltration rate shall be the lesser of the values in Table 14 and the Long-term infiltration rate. Infiltration basin drawdown time: Designed to drain dry within 72 hours after the design event using the long term soil infiltration rate: Infiltration basins will need to be refreshed and infiltration rate restored when the actual draw down time to drain dry exceeds 72 hours. 120 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.513 V. Planting Requirements a. Plant the basin with native vegetation containing a mixture of species of varying moisture tolerances. See Section 4.7 for planting guidelines. VI. Post Construction Verification a. Submit post -construction verification of volume and infiltration capacity: Submit an as -built grading plan of the infiltration basin after construction to the City to verify the design storage volume has been provided; and, ii Perform post -construction testing of actual short-term infiltration rates to ensure the basin functions as designed or corrective action will need to be taken. Refer to APPENDIX B2. VII. Facility Volume a. The size of the infiltration facility can be determined by routing methods outlined in Section 4.5.4. Infiltration facilities shall be sized to fully infiltrate the post -development NRCS Type 1 10-year 24-hr design storm and the design water surface for all facilities shall be the post developed 100-year water surface elevation. All overflows (structure or spillway) shall pass the 100-year 24-hr developed peak flow rate. b. To prevent the onset of anaerobic condition and mosquito breeding, the infiltration facility shall be designed to drain completely within 72 hours after the design storm event. VIII. Location a. If the site has the potential for contaminated or unstable soil, then these conditions shall be investigated and appropriate mitigating measures taken before designing infiltration facilities in these areas. 121 ACCESS F ----7- CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.513 PARCEL LINES AS REQUIRE INFLOW PIPE tt A SETILING POND IF REQUIRED CONNECTING SPILLWAY-__. CONTROL STRUCTURE 4- INFILTRATION POND OVERFLOW SPILLWAY ---------------------------- PLAN VIEW A 4—J NTS 4' IF H < 6' OR EXT GROUN �REQUIREO BY GEOTECHNICAL ANALYSIS v 7�-7,7�7777,- SECTION A —A NTS CIE& DETAIL IS A SCHEMATIC REPRESENTATION ONLY. ACTUAL CONFIGURATION WILL VARY DEPENDING ON SPECIFIC SITE CONSTRAINTS AND APPLICABLE DESIGN CRITERIA Figure 20 - Infiltration Facility Details 122 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.6A 4.7.6 UNDERGROUND DETENTION FACILITIES A. Introduction I. Underground detention is typically utilized on sites where developable surface area is at a minimum. Underground detention facilities can be either large diameter metal, plastic, or concrete pipe, or box -shaped facilities constructed of reinforced concrete. II. Underground detention serves as an alternative to above surface detention for stormwater flood control where there is not adequate land for an above ground pond. IIl. Perforated pipe, open bottomed structures, and covered infiltration trenches will not be considered underground detention. B. Minimum Requirements I. Location a. Underground detention facilities are to be located downstream of water quality treatment BMPs. b. Underground detention facilities should be a minimum of five feet from any structure or property boundary. C. Permanent buildings or structures shall not be placed above the underground detention facility. II. Sizing a. Pipe segments shall be sufficient in number, diameter, and length to provide the required minimum storage volume for the 100-year storm event. III. Materials a. Pipe thickness, cover, bedding, and backfill shall be designed to withstand HS-20 loading. b. Pipe joints shall be watertight, not soil tight. C. The minimum diameter of pipe allowed shall be 12 inch. d. End caps shall be designed for structural stability at maximum hydrostatic loading conditions. IV. Flow Control Structure a. The outlet pipe(s) shall discharge into a standard manhole structure. b. If an orifice plate is required to control the release rates, the plate shall be hinged to open into the detention pipes to facilitate back flushing of the outlet pipe. C. A high flow bypass shall be included to safely pass the 100-year storm event in the event of outlet structure blockage or mechanical failure. The bypass shall be located so that downstream structures will not be impacted by emergency discharges. 123 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.7A V. Buoyancy a. In moderately pervious soils where seasonal groundwater may induce flotation, buoyancy tendencies must be balanced either by ballasting with backfill or concrete backfill, providing concrete anchors, increasing the total weight, or providing subsurface drains to permanently lower the groundwater table. Calculations that demonstrate stability must be provided. VI. Access a. The maximum depth from finished grade to tank invert should be 10 feet. b. To facilitate cleaning of the pipe segments, a minimum of 3-foot diameter maintenance access ports shall be placed: i At the beginning of every pipe run, including manifolds; ii At the outlet of the detention system; iii And as otherwise necessary for proper cleaning and maintenance. C. Access ports shall have a minimum 2 foot sump. d. All tank access ports and openings shall have solid locking lids. e. All tank access ports and openings must be readily accessible by maintenance vehicles. 4.7.7 RETENTION FACILITIES A. Retention facilities are used for storage of stormwater runoff when site conditions are not conducive to infiltration, and can be used for flow control provided that: I. The stormwater discharge is properly treated prior to the entering the facility; and, II. Retention facilities shall be sized for storage of the post -developed NCRS Type 1 100-year 24-hour storm event. B. MINIMUM REQUIREMENTS. Retention facilities shall meet all requirement outlined for detention facilities and the additional requirements specified in Section 4.7.8. 4.7.8 ADDITIONAL REQUIREMENTS FOR ALL FACILITIES A. GENERAL I. The design of flow control facilities shall adhere to the following: a. Pond bottoms shall be located a minimum of 0.5 feet below the outlet to provide sediment storage. Sediment storage volume shall not be included in the design volume; and, 124 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.8B b. In general, all pond bottoms shall be sloped from 0.5% to 1 %. Roadside swales are considered flat if the swale bottom slope is 1% or less. When calculating treatment volume, the designer can assume a flat bottom for swale/pond bottom slopes up to 1 %. II. Drainage facilities shall be located within a drainage parcel. Refer to Section 4.10.2 for specific information. B. SETBACKS I. Setbacks for any detention pond, swale or ditch (measured from the maximum design operating depth) shall be at least 30 feet when located up -gradient or 20 feet when located down -gradient from septic tanks or drain fields. II. Pond overflow structures shall be located a minimum of 10 feet from any structure or property line. The toe of the berm or top of bank shall be a minimum of 5 feet from any structure or property line. III. Building Foundation: At least 50 feet from the top of the facility's slope; IV. Easement or property line: 20 feet from the top of the facility's slope; V. Floodplain: Outside 10-year High Water Level (HWL); and, VI. Drainage facilities located at, or adjacent to, schools, nursing homes, day -cares, or similar facilities: At least 200 feet. C. DRAWDOWN TIME Detention and infiltration facilities shall have a minimum subgrade infiltration rate of 0.5 inches/hour and drain completely within 72 hours after a storm event. A drawdown time of 72 hours is intended to prevent the onset of anaerobic condition and mosquito breeding. D. SIDE SLOPES Pond side slopes shall meet one of the following requirements: a. Interior side slopes shall not be steeper than 3H:1 V; b. Pond walls may be vertical retaining walls, provided that: i A fence is provided along the top of the wall for walls 2.5 feet or taller; ii An 8-foot-wide access ramp to the pond bottom is provided, with slopes less than 4:1 (horizontal to vertical); and, iii The design is by a professional engineer with structural expertise if the wall is 4 feet or more in height. E. EMERGENCY OVERFLOW SPILLWAY An emergency overflow spillway shall be provided to bypass the 100-year developed peak flow toward the downstream conveyance system in the event of plugged orifices or high flows that exceeds the design storm. 125 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.8F II. Emergency overflow spillways shall be analyzed as broad crested trapezoidal weirs and comply with the following requirements: a. The spillway shall have the capacity to pass the 100-year developed peak flow; b. The full width of the spillway shall be armored with riprap and extend downstream to where emergency overflows enter the conveyance system. The armoring may have a 4" topsoil and grass cover; C. Rip rap shall extend just beyond the point that bank and stream bed erosion occurs: d. If the detention/infiltration facility is located on an embankment, the overflow spillway shall be armored to a minimum of 10 feet beyond the toe of the embankment; and; e. The overflow path shall be identified on the construction plans and easements shall be provided as necessary. III. Engineers may choose to design the detention pond multi -stage outflow structure with an emergency bypass that can route the 100-year storm through the structure and out of the pond directly into the conveyance channel. However, due to the high potential for sedimentation and plugged orifices within these structures, an emergency overflow spillway shall still be provided in order to reduce the potential for a pond berm breach for detention ponds that require an emergency overflow spillway. F. EMBANKMENTS I. The height of an embankment is measured from the top of the berm to the catch point of the native soil at the lowest elevation. Embankments shall meet the following minimum requirements: a. Embankments 4 feet or more in height shall be constructed as recommended by a geotechnical engineer. Depending upon the site, geotechnical recommendations may be necessary for lesser embankment heights; b. Embankments shall be constructed on native consolidated soil, free of loose surface soil materials, fill, roots, and other organic debris or as recommended by the geotechnical engineer; C. Energy dissipation and erosion control shall be provided to stabilize the berm and its overflow; d. The embankment compaction shall produce a dense, low permeability engineered fill that can tolerate post -construction settlements with minimal cracking. The embankment fill shall be placed on a stable subgrade, placed in 6" lifts, and compacted to a minimum of 95% of the Modified Proctor Density (ASTM Procedure D1557); 126 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.8G e. Anti -seepage filter -drain diaphragms shall be considered on all outflow pipes and are required on outflow pipes when design water depths are 8 feet or greater; f. In the event of a berm fracture or failure, the berm shall allow the passage of water through the berm without additional erosion or failure of the berm structure. g. Embankments must be constructed by excavating a key. The key width shall equal 50 percent of the berm base width, and the key depth shall equal 50 percent of the berm height; and, h. The berm top width shall be a minimum of 4 feet. G. FENCING I. Fencing or other barriers may be required to protect the health, welfare and safety of the public. In general, fencing is required for the following: a. Drainage facilities with the first overflow at 4 or more feet above the pond bottom; b. Drainage facilities with retaining walls 2.5 feet high or taller; C. Drainage facilities located at, or adjacent to, schools, nursing homes, day - cares, or similar facilities; d. Fencing is not required for a typical infiltration swale. However, the City Engineer reserves the authority to require a fence along any swale or pond should there be a concern for safety; and, At the discretion of the City Engineer, if a pond is proposed as an amenity, i.e., enhancements to the disposal facility are proposed, such as rocks, boulders, waterfalls, fountains, creative landscaping or plant materials, the design will be reviewed on a case -by -case basis, such that the fencing requirements may be reduced or waived. II. At the discretion of the City Engineer, marking fences, terraces, shallower side - slopes, egress bars, etc. may be allowed instead of fencing. III. The minimum fencing requirements are as follows: a. The fencing shall be at least 4 feet tall unless otherwise specified by the City Engineer, and provide visual access; and, b. Gates are to be provided where drainage facilities are fenced. The gates shall be a minimum of 12 feet wide with two leaves and have locks. IV. The City Engineer reserves the authority to waive any and all fencing in commercial areas, as reviewed and accepted on a case -by -case basis by the City Engineer. 127 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.9A 4.7.9 PLANTING REQUIREMENTS A. Exposed earth on the pond bottom and interior side slopes shall be sodded, seeded, or vegetated in a timely manner, taking into account the current season. Unless a dryland grass or other drought tolerant plant material is proposed, irrigation shall be provided. All remaining areas of the tract or easement shall be sodded or planted with dryland grass or landscaped. Refer to APPENDIX F for planting guidelines. 4.7.10 LANDSCAPING A. Where space and circumstances allow, the landscaping scheme and common use areas shall be integrated with the open drainage features and into the overall stormwater plan. Plants other than turf grass have characteristics that can provide additional stormwater management benefits such as enhanced evapotranspiration and improved soil -holding capabilities. B. However, in all cases the landscaping and other uses must be subservient to the primary stormwater needs and functions. Landscaping shall not conflict with the collection, conveyance, treatment, storage, and disposal of stormwater. The following general principles should guide the landscaping and selection of plants in conjunction with stormwater facilities: I. Supplemental landscaping areas should be grouped into irregular islands and borders outside of the immediate stormwater facilities and not uniformly dispersed throughout them. The constructed stormwater features should be irregular and curved in shape to look more natural. Avoid straight lines and regular shapes where possible; II. Trees and shrubs shall not be planted on pond liners due to potential leakage from root penetration; III. Planting is restricted on berms that impound water either permanently or temporarily during storms; IV. Trees and shrubs shall not be planted within 10 feet of drainage appurtenances such as outlet control structures, manholes, catch basins, inlets and outlets, spillways, storm drain lines, and underground disposal structures such as drywells or drain -fields. The minimum spacing between the tree or shrub and the drainage structure shall be equal to the crown diameter of the mature plant; V. Trees and shrubs shall not be planted within the treatment, storage, and conveyance zones of swales, ponds, and open channels, unless treatment and storage calculations take into account the mature tree size and allow runoff to reach the drainage facilities; VI. Self-limiting plants shall be used, not spreading or self -seeding types; 128 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7. I OC VII. Full-size forest trees and trees with aggressive root systems should not be used except where space and circumstances allow. Deciduous trees with heavy shade and leaf -fall should also be avoided to allow the survival of the surrounding grass areas and not plug drainage facilities. Evergreens and smaller ornamental trees are normally better suited to urban conditions; VIII. Shrubs should be upright in form and groundcovers should have neat growth patterns to assist in their maintenance and that of the surrounding grass areas; and, IX. The plant selection needs to consider the native soil conditions and altered moisture conditions created by the stormwater facilities. The plants need to be adaptable to the changes in site conditions. Plants that are self- sufficient and self-limiting do not require year-round irrigation and require minimal care are encouraged. Guidelines for plantings are listed in APPENDIX F. C. MAINTENANCE I. Maintenance is of primary importance for drainage facilities to operate as designed. The requirements of Section 4.10 shall be met as applicable. 4.7.11 SPECIAL REQUIREMENTS A. FLOODPLAINS I. Floodplain requirements are administered by the City Planning Department. Contact the City Flood Plain Administrator for more information and specific requirements. II. When any property is developed in or around identified Special Flood Hazard Areas all work must conform to the requirements of the City of Kalispell Flood Plain Management Ordinance. B. WETLANDS I. A wetland analyses is required for all new development and redevelopment. A wetland checklist, located in APPENDIX A is required to be completed and submitted with the drainage report. The Wetland checklist helps to identify if wetland resources may be present and further wetland assessment is required. If you check "yes" for any wetland indicators on the checklist, a Wetland Assessment outlined in the Kalispell Stormwater Quality Management Plan is required. The assessment must be performed by a wetland professional trained and familiar with the current US Army Corps of Engineers Regional Supplements for Wetland Delineations and the most recent Army Corps of Engineers guidance for Jurisdictional Determinations. II. Protection strategies have been developed to protect wetlands from changes to their hydrology, plant diversity, function and water quality. An on -site wetland assessment is required to determine the stormwater management classification for each wetland. Refer to Stormwater Quality Management Plan Chapter 3.4 for the procedure. The Stormwater Ouali , Management Plan can be obtained from the Kalispell Public Works Department. 129 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.11 C III. The protection standards and classifications acknowledge that wetlands demonstrate varying susceptibility to stormwater impacts. The standards for the closest downstream wetland will apply. Unless the wetland discharges into a lake, flow control standards shall apply to discharges leaving the overall site. C. CLOSED DEPRESSIONS I. Closed depressions are natural low areas that hold a fixed volume of surface water. Depending upon soil characteristics, a closed depression may or may not accumulate surface water during wet periods of the year. Some closed depressions may be classified as wetlands. If so, the engineer shall comply with the wetland criteria specified in this section. Analysis of closed depressions shall include the following at a minimum: a. Identification of the location of the closed depression on the pre -developed basin map; b. A routing analysis of the drainage basins contributing to the closed depression to estimate the peak flow rates and volumes entering the closed depression in the pre -developed condition; C. An estimation of the storage capacity of the closed depression for the 100- year storm event; d. If the closed depression will be filled in, a facility shall be provided that has the capacity to store the 100-year 24-hour volume that was historically intercepted by the closed depression. This is in addition to the drainage facilities required for flow control and treatment due to the increase in stormwater runoff. The construction plans shall include a grading plan of any closed depression areas to be filled in. The grading plan shall show both existing and finish grade contours. The plans shall also specify compaction and fill material requirements; and, Closed depressions have the same flow control requirement as retention facilities. 4.7.12 REGIONAL DETENTION PONDS A. Regional Detention Ponds are located along major stormwater conveyances and natural drainage ways. Most regional facilities serve more than a single development within a given contributing drainage basin. Regional facilities have the potential to lessen flooding in existing drainage problem areas. B. The City of Kalispell has adopted the 2008 Stormwater Facility Plan Update with proposed locations for regional stormwater facilities and mapped natural drainage areas within the study area. The updated plan provides design data for drainage basins including basin delineations, drainage areas, and existing natural drainage ways. A quantitative analysis provides approximate pond storage volumes, allowable peak discharge flow rates and potential regional pond locations. 130 CHAPTER 4 — STORMWATER DESIGN SECTION 4.7.12C C. Project owners shall coordinate with the City Staff early in the planning process when the project site is in an area for which natural drainage ways and regional detention ponds are featured in the 2008 Stormwater Facility Plan Update. 4.8 NATURAL AND CONSTRUCTED CONVEYANCE SYSTEMS 4.8.1 INTRODUCTION A. A conveyance system includes all natural or constructed components of a storm drain system that collects stormwater runoff and conveys it away from structures, minimizing the potential for flooding and erosion. B. Conveyance facilities consist of curbs and gutters, inlets, storm drains, catch basins, channels, ditches, pipes, and culverts. The placement and hydraulic capacities of storm drain structures and conveyance systems shall consider the potential for damage to adjacent properties and contain flooding within traveled roadways. The conveyance system shall also provide discharge capacity sufficient to convey the design flow at velocities that are self-cleaning without being destructive to the conveyance facilities. These objectives are achieved by designing all conveyance facilities using the design storm event specified for the given facility and by adhering to requirements such as minimum velocity, freeboard, cover, etc. C. A properly designed conveyance system maximizes hydraulic efficiency by using the proper material, slope, and size. Constructed conveyance systems should emulate natural, pre -developed conditions to the maximum extent practical. Field -verified defined natural drainage ways must be preserved and protected; filling them in and building on top of them is not an acceptable practice. D. Inflow and discharge from the system shall occur at the natural drainage points in the same manner as the pre -developed condition. 4.8.2 APPLICABILITY A. All projects shall comply with this Basic Requirement: Conveyance Natural and Constructed regardless of whether the project meets the regulatory threshold. 4.8.3 NATURAL AND CONSTRUCTED CHANNELS A. CHANNEL ANALYSIS I. A channel analysis shall be performed for all constructed channels proposed for a project and for all field -verified existing natural drainage ways/channels present on -site (refer to 4.8.3 for details). The following requirements apply to the Drainage Report and the road and drainage plans, when applicable: 131 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.313 B. Complete channel calculations shall be provided, indicating the design peak flow rates and assumptions, such as channel shape, slope and Manning's coefficient (see Table 9); C. Calculations, including the velocity, capacity, and Froude number shall be provided for each distinct channel segment whenever the geometry of the channel changes, i.e., if the slope, shape or roughness changes significantly. The centerline and direction of flow for all constructed drainage ditches or natural channels within the project limits are to be clearly shown on the construction plans and basin map. For all proposed channels, stationing information shall be provided at all angle points; Calculations shall support the riprap area, thickness, riprap size and gradation, and filter blanket reinforcement for all channel protection, which shall be provided when permissible velocities are exceeded (see Table 17). This information shall be included in the plans; a. The Froude number shall be checked near the beginning and near the end of a channel that has significant grade changes to determine if a hydraulic jump occurs (as indicated by the Froude number changing from <1 to >1, or vice versa). Since it is difficult to correlate the location of a hydraulic jump to the actual location in the field, the engineer shall propose evenly spaced riprap berms, check dams, or other protective measures to ensure that the jump does not erode the conveyance facility; b. When geosynthetics are used for channel protection, the plans shall clearly specify fabric type, placement, and anchoring requirements. Installation shall be per the manufacturer's recommendation; and, C. Plans for grass -lined channels shall specify seed mixture and irrigation requirements, as applicable. 132 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3D Table 17 - Permissible Velocities for Channels with Erodable Linings,Based on Uniform Flow in Continuously Wet, Aged, Channels Ill Soil Type Of Lining (Earth; No Vegetation) Maximum Permissible Velocities (feet/second) Clear Water Fine sand (non -colloidal) 1.5 Sandy loam (non -colloidal) 1.7 Silt loam (non -colloidal) 2.0 Ordinary firm loam 2.5 Volcanic ash 2.5 Fine gravel 2.5 Stiff clay (very colloidal) 3.7 Graded, loam to cobbles (non -colloidal) 3.7 Graded, silt to cobbles (colloidal) 4.0 Alluvial silts (non -colloidal) 2.0 Alluvial silts (colloidal) 3.7 Coarse gravel (non -colloidal) 4.0 Cobbles 5.0 Shales and hard pans 6.0 D. MINIMUM REQUIREMENTS Slope a. Minimum grades for constructed channels shall be as follows: i 1.0% for asphalt concrete; and, ii 0.5% for cement concrete, graded earth, or close -cropped grass. II. Side Slopes a. Ditch cross -sections shall be trapezoidal; and, b. The side slope of roadside ditches shall be a maximum of 4:1. 1 Source: Special Committee on Irrigation Research, American Society of Civil Engineers, 1926. 133 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3E III. Location a. Constructed channels shall not be placed within or between residential lots. Ditches, swales, and channels shall be located within a drainage parcel. Ditches, swales, or channels may be allowed to traverse through lots in large -lot subdivisions (lots of 1 acre or more) and consideration may be given to placement within an easement versus a parcel. The City Engineer will review these proposals on a case by -case basis. IV. Depth a. The minimum depth of open channels shall be 1.3 times the flow depth or 1 foot; whichever is greater. V. Velocity a. Table 17 lists the maximum permissible mean channel velocities for various types of soil and ground cover. If mean channel velocities exceed these values, channel protection is required (refer to Section G). In addition, the following criteria shall apply: i Where only sparse vegetative cover can be established or maintained, velocities should not exceed 3 feet/second; ii Where the vegetation is established by seeding, velocities in the range of 3 to 4 feet/second are permitted; iii Where dense sod can be developed quickly or where the normal flow in the channel can be diverted until a vegetative cover is established, velocities of 4 to 5 feet/second are permitted; and, iv On well -established sod of good quality, velocities in the range of 5 to 6 feet/second are permitted. E. CHANNEL DESIGN I. Channel Capacity a. Open channels shall be sized using the following variation of Manning's formula. 2 1 Equation 20 Q = V * A = 1.486*A*R3*SZ n Where:Q = rate of flow (cfs); V = mean velocity in channel (feet/second); A = cross -sectional area of flow in the channel (square feet); R = hydraulic radius (feet); where R = A/P, and P = wetted perimeter (feet) S = channel slope (feet/foot); and, n = Manning's roughness coefficient (Table 9). 134 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3F b. Note: Manning's equation will give a reliable estimate of velocity only if the discharge, channel cross-section, roughness, and slope are constant over a sufficient distance to establish uniform flow conditions. Uniform flow conditions seldom, if ever, occur in nature because channel sections change from point to point. For practical purposes, however, Manning's equation can be applied to most open channel flow problems by making conservative assumptions. F. Energy Dissipation Design I. An energy dissipater is useful in reducing excess velocity, as a means of preventing erosion below an outfall or spillway. Common types of energy dissipaters for small hydraulic works are: hydraulic jumps, stilling wells, riprap outfall pads, and gabion weirs. G. Channel Protection I. Channel velocities shall be analyzed at the following locations, and if they are found to be erosive, channel protection shall be provided: a. At the top of a watershed, at the point where the stormwater runoff becomes concentrated into a natural or constructed channel; b. At all changes in channel configuration (grade, side slopes, depth, shape, etc.), if an erosive velocity is determined at a change in channel configuration, the velocity shall be evaluated up the channel until the point at which the velocity is determined not to be erosive; and, C. At periodic locations along the entire channelized route. II. A material shall be selected that has revetment and armoring capabilities, and the channel shall be analyzed using the Manning's "n" value for that material to determine if the material will reduce the velocity in the channel. In some cases, vegetative cover (natural grasses, etc.) may provide excellent protection without changing the flow characteristics and should be evaluated. If the calculations reveal that common materials such as riprap are not adequate, stronger protection such as gabions and/or stilling pools may be necessary. H. Riprap Protection at Outlets I. If the velocity at a channel or culvert outlet exceeds the maximum permissible velocity for the soil or channel lining, channel protection is required. The protection usually consists of a reach between the outlet and the stable downstream channel lined with an erosion -resistant material such as riprap. II. The ability of riprap revetment to resist erosion is related to the size, shape, and weight of the stones. Riprap-lined channels are required to have filter fabric under the riprap. Riprap material shall be blocky in shape rather than elongated. The riprap stone shall have sharp, angular, clean edges. Riprap stone shall be reasonably well -graded and a minimum size of 6 inches. 135 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3H III. Apron Dimensions: The length of an apron (La) is determined using the following empirical relationships that were developed for the U.S. Environmental Protection Agency (ASCE, 1992): Equation 21 La = 1'8Q + (7 * Do); for TW < Do Doff or Equation 22 La = 3Q + (7 * Do); for TW >_ Do Dot Where: La = length of apron (feet) Do = maximum inside culvert width (feet); Q = pipe discharge (cfs); and, TW=tailwater depth (feet). a. When there is no well-defined channel downstream of the apron, the width, W, of the apron outlet as shown in Figure 21, shall be calculated using Equation 23 or Equation 24: Figure 21 - Riprap Revetment at Outfall Schematic 136 Equation 23 Equation 24 IV. Equation 25 Equation 26 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3H W = 3 * Do + (0.4 * La); for TW >_ °° 2 or W = 3 * Do + La; f or TW <Do b. When there is a well-defined channel downstream of the apron, the bottom width of the apron should be at least equal to the bottom width of the channel and the lining should extend at least 1 foot above the tailwater elevation. The width of the apron at a culvert outlet should be at least 3 times the culvert width. Apron Materials: a. The median stone diameter, D50 is determined from the following equation: 4 0.02*Q3 D5_ o Da*TW Where: D50 = the diameter of rock, for which 50% of the particles are finer. b. The riprap should be reasonably well graded, within the following gradation parameters: 1.25<_D"<_1.50and D15=0.5and D"'<_0.25 D50 D30 D50 Where: Dmax = the maximum particle size; Dmin = the minimum particle size; and, D15 = the diameter of rock, for which 15% of the particles are finer. V. Minimum Thickness: The minimum thickness of the riprap layer shall be 12 inches, Dmax or 1.5*D50, whichever is greater. VI. Filter Blanket: A filter fabric blanket shall be placed under the riprap. 137 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3I I. PRESERVATION OF NATURAL DRAINAGE WAYS (NDW) I. Introduction a. New development shall be designed to protect existing natural drainage features that convey or store water or allow it to infiltrate into the ground in its natural location. Preserving the NDW will help ensure that stormwater runoff can continue to be conveyed and disposed of at its natural location. Preservation will also increase the ability to use the predominant systems in conjunction with regional stormwater facilities. b. Projects located within the City of Kalispell shall refer to the City of Kalispell's 2008 Storm Water Facility Plan Update for specific details with regards to the location of NDW. II. Definitions a. The drainage ways that need to be preserved have been mapped and defined in the City of Kalispell's 2008 Storm Water Facility Plan Update. Each natural drainage way shall be designed to pass the 100-year 24-hour storm event as described in the Plan Update. Because every site is unique, the City Engineer shall make interpretations, as necessary, based on site visits and technical information as to the exact location on a project site. The City Engineer may also require the project owner to provide engineering information to assist in this determination. b. The maps denoting these drainage ways are not definitive; a computer program was used to identify the drainage ways. The maps are only one tool that may be used to identify existing natural drainage ways; field verification will typically be required to fully identify the existence of a drainage way and its significance with regard to a natural conveyance system. C. All projects shall be reviewed for the presence of natural drainage ways mapped in the 2008 Stormwater Facility Plan, and a determination will be made as to their significance with regard to preservation of natural conveyance and potential use as part of a regional system. III. Protection No cuts or fills shall be allowed in predominant natural drainage ways except for perpendicular driveway or road crossings with engineering plans showing appropriately sized culverts or bridges. Natural drainage ways shall be preserved for stormwater conveyance in their existing location and state, and shall also be considered for use as regional facilities; 138 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.3I b. Less prominent drainage ways in a non-residential development and in a residential development containing lots 1 acre or smaller may be realigned within the development provided that the drainage way will enter and exit the site at the pre -developed location and that discharge will occur in the same manner as prior to development; C. Realignment of a less prominent drainage way shall be defined as still following the "basic" flow path of the original drainage way. An acceptable example would be if the drainage way is proposed to be realigned such that it will follow a new road within the proposed development, and will be left in its existing state or utilized as part of the project's on -site stormwater system. d. Stormwater leaving the site in the same manner shall be defined as replicating the way the stormwater left the site in its existing condition. If the drainage way is preserved in its existing location and is left undisturbed, this goal should be met; e. If the City Engineer accepts the proposal to allow a less predominant drainage way to be routed through the site via a pipe or approved drainage material, the following additional criteria shall be met: i Where the less prominent drainage way enters the site, the design shall ensure that the entire drainage way is "captured" as it enters the site; i.e., the surrounding property shall not be regraded to "neck -down" the drainage way so that it fits into a drainage easement or tract or structure intended to capture and reroute the off -site stormwater runoff, ii Where the less prominent drainage way exits the site, the design shall ensure that the stormwater leaves the pipe, pond or structure a significant distance from the edge of the adjacent property so that by the time the stormwater reaches the property boundary, its dispersal shall mimic that of the pre -developed condition; and, iii Since some of the less prominent drainage ways may iv also be useful for managing regional stormwater, if identified as a significant drainage way, i.e., necessary conveyance for flood control, or being considered as a connection to a planned regional facility or conveyance route, then the drainage way may be subject to the same limitations and criteria as a predominant drainage way. f. The size of the tract or easement containing the drainage way shall be determined based on an analysis of the existing and proposed stormwater flows directed to these drainage systems and any access and maintenance requirements found in this manual; and, 139 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.4A g. All new development containing lots that are 1 acre or smaller shall be required to set aside the drainage way as open space in a separate parcel. For new development containing lots that are greater than 1 acre, the drainage way may be set aside in either a parcel or an easement. 4.8.4 CULVERTS A. Introduction I. A culvert is a short pipe used to convey flow under a roadway or embankment. Culverts are used to pass peak flow from defined drainage ways identified on contour maps. A culvert shall convey flow without causing damaging backwater flow constriction, or excessive outlet velocities. Factors to be taken into consideration in culvert design include design flows, the culvert's hydraulic performance, the economy of alternative pipe materials and sizes, horizontal and vertical alignment, and environmental concerns. B. CULVERT ANALYSIS I. When applicable, the following items shall be included in the Drainage Report and on road and drainage plans: II. Complete culvert calculations that state the design peak flow rates, velocities at the inlet and outlet, flow control type, and design information for the culvert such as size, slope, length, material type, and Manning's coefficient (refer to Table 18); a. Headwater depths and water surface elevations for the design flow rate; b. Roadway cross-section and roadway profile; Location information for each of the culvert inverts and invert elevations; d. Type of end treatment (wingwall, flared end sections, etc); e. Wall thickness; and f. Inlet or outlet flow control. C. MINIMUM REQUIREMENTS FOR CULVERTS I. Peak Flow Rate a. Culverts shall be sized to handle the design peak flow rates calculated using the methods described in Section 4.5 and the design criteria specified in Section 4.2; b. To avoid saturation of the road base, culverts shall be designed such that the water surface elevation for the design storm event does not exceed the elevation of the base course of the roadway; and, C. Culverts shall be designed to convey the 100-year peak storm event without damage. 140 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.4C Table 18 - Manning's Roughness Coefficient (n) For C'nlverts Material Type n Reinforced concrete pipe (RCP) 0.013 Ductile iron 0.412-.015 HDPE121 0.012 PP3 0.012 CMP 0.024 II. Allowable Headwater Elevation a. Headwater is the depth of water at the culvert entrance at a given design flow. Headwater depth is measured from the invert of the culvert to the water surface; and, b. Culverts shall be designed to carry the design runoff with a headwater depth less than 2 times the culvert diameter for culverts 18 inches or less in diameter, and less than 1.5 times the culvert diameter for culverts more than 18 inches in diameter. III. Velocity and Slope a. To avoid silting, the minimum velocity of flow through culverts shall be 2.5 feet/second and the minimum slope shall be 0.5%. IV. Diameter a. Table 19 lists required minimum culvert diameters. Table 19 - Minimum Culvert Sizes Culvert Location Minimum Size (inches) Under public roads 12 Under private roads 12 Under driveways/approaches 12 1 Manning's Coefficient (n) can also be based on manufactures specifications. 2 HDPE = high -density polyethylene; 3 PP = Polypropylene 4 CMP = corrugated metal pipe. 141 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.4C V. Allowable Pipe Material and Pipe Joints a. Corrugated metal pipe: i Joints shall be rubber gasketed and securely banded. b. Ductile iron; i Joints shall be flanged, bell and spigot, or restrained mechanical joints; C. Reinforced concrete: i Joints shall be rubber gasketed; d. High -density polyethylene (HDPE): i Pipes shall have a smooth interior and annular exterior corrugations; ii Joints shall be watertight according to ASTM D3212. Gaskets shall meet ASTM F477 iii Corrugated couplings shall be split collar, engaging at least 2 full corrugations. e. Polypropylene i Pipes shall have a smooth interior and annular exterior corrugations meeting ASTM F2736 (12"-30") or ASTM F2881 (36"-60") and AASHTO MP-21; ii Joints shall be joined with a gasketed integral bell & spigot joint meeting the requirements of ASTM F2736 or ASTM F2881, for the respective diameters; iii Corrugated couplings shall be split collar, engaging at least 2 full corrugations. VI. Pipe Anchoring a. For grades greater than or equal to 20%, anchors are required unless calculations or the manufacturer's recommendations show that they are not necessary. VII. Placement/Alignment a. Generally, culverts shall be placed on the same alignment and grade as the drainage way. Design shall consider changes of conditions over time and use design measures such as: i Cambering or crowning under high tapered fill zones; ii Raising intakes slightly above the flow line to allow for sedimentation; iii Using cantilevered outfalls away from road banks to allow for toe erosion; and, iv Using drop inlets or manholes to reduce exit velocities on steep terrain. 142 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.4C VIII. Angle Points a. The slope of a culvert shall remain constant throughout the entire length of the culvert. However, in situations where existing roadways are to be widened, it may be necessary to extend an existing culvert at a different slope; the location where the slope changes is referred to as the angle point. The change in slope tends to create a location in the culvert that catches debris and sediment. If an extension of a culvert is to be placed at a different grade than the existing culvert, a manhole shall be provided at the angle point to facilitate culvert maintenance. IX. Outfalls a. Outfalls shall conform to the requirements of all federal, state, and local regulations. Erosion control shall be provided at the culvert outfall. Refer to Section 4.8.3H for additional information regarding outfall protection. X. Structural Design a. For culverts under roadways, the amount of cover over the culvert is defined as the distance from the top of the pipe to the bottom of the pavement. It does not include asphalt or concrete paving above the base. The minimum amount of cover is 2 feet for culverts. All pipe designs shall meet AASHTO HS-20 loading criteria. b. Also, extreme fill heights (20 feet or greater) may cause structural damage to pipes and will require a special design or adherence to the manufacturer's recommendations. Refer to manufacturers requirements for the maximum cover for different pipe materials and sizes. XI. End Treatments a. Culverts shall have end treatments. The type of end treatment used on a culvert depends on many interrelated and often conflicting considerations: Projecting Ends is a treatment in which the culvert is simply allowed to protrude out of the embankment. This is the simplest and most economical. There are several disadvantages such as susceptibility to flotation and erosion, safety when projecting into a roadway clear zone (an area beyond the traveled roadway provided for recovery of errant vehicles), and aesthetic concerns; Beveled End Sections consist of cutting the end of the culvert at an angle to match the embankment slope surrounding the culvert. Beveled ends should be considered for culverts 6 feet in diameter or less. Structural problems may be encountered for larger culverts not reinforced with a headwall or slope collar; 143 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.41) iii Flared End Sections are manufactured culvert ends that provide a simple transition from culvert to a drainage way. Flared end sections are typically only used on circular pipe or pipe arches. This end treatment is typically the most feasible option in pipes up to 48 inches in diameter. Safety concerns generally prohibit their use in the clear zone for all but the smallest diameters; iv Headwalls are concrete frames poured around a beveled or projecting culvert. They provide structural support and eliminate the tendency for buoyancy. They are considered feasible for metal culverts that range from 6 to 10 feet in diameter. For larger diameters, a slope collar is recommended. A slope collar is a reinforced concrete ring that surrounds the exposed culvert end; or, v Wingwalls and Aprons are intended for use on reinforced concrete box culverts. Their purpose is to retain and protect the embankment, and provide a smooth transition between the culvert and the channel. D. CULVERT DESIGN Culvert analysis is typically performed using commercially available computer software. If hand calculations are proposed, example calculations can be found in technical publications and open channel hydraulics manuals. 4.8.5 STORM DRAIN SYSTEMS A. INTRODUCTION I. A storm drain system is a network of pipes that convey surface drainage from catch basins or other surface inlets, through manholes, to an outfall. II. The design of storm drain systems shall take into consideration runoff rates, pipe flow capacity, hydraulic grade line, soil characteristics, pipe strength, potential construction problems, and potential impacts on down -gradient properties. B. PIPE ANALYSIS I. The following items shall be included in the Drainage Report, or on road and drainage plans: a. A basin map showing on -site and off -site basins contributing runoff to each inlet, which includes a plan view of the location of the conveyance system; b. Complete pipe calculations that state the design peak flow rates and design information for each pipe run, such as size, slope, length, material type, and Manning's coefficient (see Table 20); C. Velocities at design flow for each pipe run; d. The hydraulic grade line at each inlet, angle point, and outlet; and, e. The minimum depth from finish grade to pipe invert and the minimum pipe slope necessary to satisfy the freeboard and self-cleaning velocity requirements shall be provided. 144 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.513 Table 20 - Manning's Roughness Coefficient (n) For Closed Svstems Material Type n Reinforced concrete pipe (RCP) 0.013 Ductile iron 0.012-.015 HDPE 0.012 PVC (only allowed in closed system) 0.012 pp[4]0.012 IL Allowable Pipe Material and Pipe Joints a. Ductile iron; i Joints shall be flanged, bell and spigot, or restrained mechanical joints; b. Reinforced concrete: i Joints shall be rubber gasketed; C. Polyvinyl Chloride (PVC): i Pipe shall be install following procedures outlined in ASTM D2321; ii Joints shall conform to ASTM D3212, and gasket shall conform to ASTM F477; iii Pipe must be a min of SDR 35 or a constant stiffness thermoplastic pipe and meet the requirements of ASTM D3034 or ASTM F949, respectively; d. High -density polyethylene (HDPE): i Pipes shall have a smooth interior and annular exterior corrugations; ii Joints shall be watertight according to ASTM D3212. Gaskets shall meet ASTM F477 iii Corrugated couplings shall be split collar, engaging at least 2 full corrugations. iv ADS N-12 smooth interior pipe or approved equal; 1 Manning's Coefficient (n) can also be based on manufactures specifications. 2 HDPE = high -density polyethylene 3 PVC = Polyvinyl chloride 4 PP = Polypropylene 145 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.5C Polypropylene i Pipes shall have a smooth interior and annular exterior corrugations meeting ASTM F2736 (12"-30") or ASTM F2881 (36"-60") and AASHTO MP-21. ii Joints shall be joined with a gasketed integral bell & spigot joint meeting the requirements of ASTM F2736 or ASTM F2881, for the respective diameters. iii Corrugated couplings shall be split collar, engaging at least 2 full corrugations. C. MINIMUM REQUIREMENTS I. Peak Flow Rate: a. Closed pipe systems shall be sized to handle the design peak flow rates. These peak rates can be calculated using the methods described in Section 4.5 and the design criteria specified in Section 4.2. II. Hydraulic Grade Line: a. The hydraulic grade line (HGL) represents the free water surface elevation of the flow traveling through a storm drain system. Pipes in closed systems will be sized by calculating the HGL in each catch basin or manhole. A minimum of 0.5 feet of freeboard shall be provided between the HGL in a catch basin or manhole and the top of grate or cover. III. Pipe Velocities and Slope: a. The pipe systems shall be designed to have a self-cleaning velocity of 2.5 feet/second or greater calculated under full flow conditions even if the pipe is only flowing partially full during the design storm. b. Pipe velocities should not be excessively high since high flow velocities (approaching and above 10 feet/second) cause abrasion of the pipes. When the design velocities are 10 feet/second or greater, manufacturer's recommendations demonstrating that the pipe material can sustain the proposed velocities shall be provided. C. When the grade of a storm pipe is greater than or equal to 20%, pipe anchors are required at the joints, at a minimum, unless calculations and manufacturer's recommendations demonstrate that pipe anchors are not needed. Pipe anchor locations are to be defined on the plans, and a pipe anchor detail shall be referenced or provided. IV. Pipe Diameter and Length: The minimum pipe diameter shall be 12 inches, and the maximum length of pipe between junctions shall be no greater than 400 feet. No pipe segment shall have a diameter smaller than the upstream segments. 146 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.51) V. Placement and Alignment: a. No storm drain pipe in a drainage easement shall have its centerline closer than 5 feet to a private rear or side property line. A storm drain located under a road shall be placed in accordance with the City Engineer's requirements or standard plans. b. A storm drain system located in the road shall not be placed vertically under the curb and gutter. C. If it is anticipated that a storm drain system may be expanded in the future, provisions for the expansion shall be incorporated into the current design. d. Storm pipe shall not be placed in the street boulevard. VI. Outfalls: a. Pipe outfalls shall be placed on the same alignment and grade as the drainage way. Outfalls shall conform to the requirements of all federal, state, and local regulations. Erosion control is required at the storm system outfalls. Refer to Section 4.8.3H for additional information regarding outfall protection. b. Outfalls shall be located at the downstream side of culvert crossings. VII. Structural Design: a. The amount of cover over the pipe is defined as the distance from the top of the pipe to the bottom of the pavement. The minimum cover shall meet manufacturer's recommendations for AASHTO HS-20 loading criteria. VIII. Inverts at Junctions: a. Whenever two pipes of the same size meet at a junction, the downstream pipe shall be placed with its invert 0.1 feet below the upstream pipe invert. When two different sizes of pipes are joined, pipe crowns shall be placed at the same elevation. The exception to this rule is at drop manholes. Exceptions may be allowed by the City Engineer when topographic conditions will significantly impact the depth of the disposal location. IX. Combined Systems: a. Combined sanitary and stonnwater sewer systems are prohibited. D. PIPE DESIGN I. To analyze the conveyance capacity of a closed pipe system, the following general steps may be followed when steady flow conditions exist, or conditions can be accurately approximated assuming steady flow conditions: a. Estimate the size of the pipes assuming a uniform flow condition, using Equation 20. Refer to Table 9 for Manning's coefficient values; b. For the pipe sizes chosen, determine uniform and critical flow depth; 147 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.6A C. Determine if upstream (accelerated) flow conditions or downstream (retarded) flow conditions exist. Subcritical flow occurs when downstream conditions control. Supercritical flow occurs when upstream conditions control. Determine what flow regime will occur by comparing uniform flow depth, critical flow depth, and initial flow depth. Identify hydraulic jump locations, and where any other discontinuity of flow depth will occur; and, d. Conduct a more detailed analysis by computing the hydraulic grade line. The direct step method or standard step method is often used to calculate the hydraulic grade line. For supercritical flow, begin at the upstream end and compute flow sections in consecutive order heading downstream. For sub - critical flow, begin at the downstream end and compute flow sections in consecutive order heading upstream. II. The analysis of closed pipe systems is typically done using commercially available computer software packages. If hand calculations are proposed, example calculations can be found in technical publications on open channel hydraulics, such as: "Handbook of Hydraulics", by Brater and King; and "Open -Channel Hydraulics" by French. 4.8.6 GUTTERS A. Introduction I. A gutter is a section of pavement adjacent to a roadway that conveys water during a storm runoff event. Gutter flow calculations are necessary to establish the spread of water onto the shoulder, parking lane, or travel lane. II. Roadways shall have an adequate non -flooded width to allow for the passing of vehicular traffic during the design storm events and shall not over top the curb onto the boulevard or sidewalk. The non -flooded width (L) is shown in Figure 22and the minimum non -flooded widths for various road classifications are outlined in Table 21. GUTTER FLOW L CURB SIDEWALK Figure 22 - Non -Flooded Road Width (L) 148 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.613 Table 21 - Non -Flooded Road Width Requirements Road Classification Non -Flooded Width (L) Private Road 12 feet Local Street 12 feet Collector Street, 2 Lane 16 feet Arterials Per City Engineer Other road types Per City Engineer III. The non -flooded width shall be evaluated at low points and at proposed inlet locations. The non -flooded width shall also be evaluated at intersections. Bypass flow shall be limited to 0.1 cfs at intersections and at the project boundary. IV. Non -flooded width and flow depth at the curb are often used as criteria for spacing pavement drainage inlets (curb or grate inlets). Drainage inlets shall be spaced so that the non -flooded width requirements are met and stormwater does not flow over the back of the curb. V. Spacing shall not exceed 400 feet regardless of flooded width and flow depth compliance. Generally, inlets shall be placed in the uphill side of the curb return. Additionally, the first inlet shall not be located more than 600 feet from the point where the gutter flow path originates. VI. Gutters shall have a minimum longitudinal slope of 0.5%. B. GUTTER ANALYSIS The drainage report shall include complete gutter calculations that state the design peak flow rates, design flow depth, road cross slope, road grade, and non - flooded width. II. The equation for calculating gutter flow is a modified version of Manning's equation. Equation 27 Q = Where: 0.56*SX1.67 *SL0.5 *T•2.67 n Q = flow rate (cfs); n = Manning's coefficient (from Table 22); SL = longitudinal slope of the gutter (feet/foot); S,t = cross slope (feet/foot); and, T = spread (feet). 149 CHAPTER 4 — STORMWATER DESIGN SECTION 0 Table 22 - Mannin 's Roughness Coefficients (n) for Street and Pavement Gutters[]] Type of Gutter or pavement n Concrete gutter, troweled finish 0.012 Asphalt Pavement Smooth Texture 0.013 Rough Texture 0.016 Concrete pavement Float finish 0.014 Broom finish 0.016 C. GUTTER DESIGN I. Uniform Gutter Section a. Uniform gutter sections have a cross slope that is equal to the cross slope of the shoulder or travel lane adjacent to the gutter (see Figure 23). The spread (T) in a uniform gutter section can be calculated using Equation 28 and solving for T (spread) as follows: Equation 28 T = ( Q*n *n o.$)0.375 0.56*Sx *SL S Figure 23 - Uniform Gutter Section b. An example calculation for determining the non -flooded width and the depth of flow for a uniform gutter section is provided in APPENDIX G1. 1 Source: Federal Highway Administration (FHWA), Hydraulic Engineering Circular No. 22, Second Edition 150 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.7A 4.8.7 DRAINAGE INLETS A. INTRODUCTION I. Drainage inlets are used to collect runoff and discharge it to a storm drainage system. They are typically located in gutter sections, paved medians, and roadside and median ditches. II. Inlets most commonly used in the City of Kalispell are as follows: a. Grate Inlets consist of an opening in the gutter or ditch covered by a grate. They perform satisfactorily over a wide range of longitudinal slopes. Grate inlets generally lose capacity as the grade of the road, gutter or ditch increases. b. Curb Inlets (combination inlets) consist of both a curb -opening and a grate inlet. They offer the advantages of both grate and curb inlets, resulting in a high capacity inlet. III. There are many variables involved in designing the number and placement of inlets, and in determining the hydraulic capacity of an inlet. The hydraulic capacity of a storm drain inlet depends upon its geometry as well as the characteristics of the gutter flow. Inlet capacity governs both the rate of water removal from the gutter and the amount of water that can enter the storm drainage system. Inadequate inlet capacity or poor inlet location may cause flooding on the roadway resulting in a hazard to the traveling public. B. MINIMUM REQUIREMENTS I. Peak Flow Rate: a. The capacity of drainage inlets shall be determined using the design peak flow rates. These rates can be calculated using the methods described in Section 4.5 and the design storm criteria specified in Section 4.2. Bypass flow shall be limited to 0.1 cfs at intersections and at the project boundary. Il. Structures: a. Storm drain manhole ring and cover shall be as shown in Standard Detail DR.8. Open grates shall be used only in paved area; b. Storm drain inlets shall be as follows: Straight (ST.8) and Curb & Gutter (ST.6) Applications East Jordan Iron Works #7222, Olympic Foundry SM49B, or approved equal; and, ii Drive Over Curb & Gutter (ST.7) Applications East Jordan Iron Works 47711, Olympic Foundry SM44, or approved equal. 151 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.7B C. Catch basins shall be used in all public and private roads; d. Catch basins, inlets, and storm manholes shall be placed at all breaks in grade, pipe size change, and horizontal alignments; e. Catch basins, inlets, and storm manholes shall have a minimum 24" sump below the lowest pipe invert elevation; f. Pipe runs shall not exceed 400 feet for all pipe sizes; g. The first inlet shall not be located more than 600 feet from the point where the gutter flow path originates; and h. Horizontal and vertical angle points shall not be allowed in a storm system unless a manhole is provided for cleaning. III. Grates: a. All grate inlets shall follow requirement set in the City of Kalispell Standards for Construction and Design; b. Grate inlets on grade shall have a minimum spacing of 20 feet to enable the bypass water to reestablish its flow against the face of curb; C. Drainage inlets shall not be located on the curved portion of a curb return; d. Grates shall be depressed to ensure satisfactory operation; the maximum depression is 1 inch; and, e. Inlets with larger openings may be used for additional capacity but must be approved by the City Engineer. IV. Curb Inlets: a. All curb inlets shall follow requirement set in the City of Kalispell Standards for Design and Construction. V. Concrete Aprons: a. Concrete aprons shall be used at the entrance to all open grate manholes, catch basins, and curb inlets. Aprons shall slope toward the grate as shown in the Standard Detail DR.2. b. A minimum 2-foot apron shall be used with inlets when no curb and gutter is present. VI. Inlet Placement: a. Inlets shall be located at intersections to prevent the flow from crossing the intersection. b. Inlets at intersections shall be located so they do not encroach upon the curb return. C. No drainage structure shall be permitted at an ADA ramp. 152 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.7C C. DRAINAGE INLET DESIGN Grate Inlets, Continuous Grade: a. The capacity of an inlet on a continuous grade can be found by determining the portion of the gutter discharge directly over the width of the inlet. On continuous grades (assuming that the grate has the capacity to intercept the entire flow rate directed toward it), the amount of stormwater intercepted by a grate is equal to the amount of stormwater runoff flowing directly over the grate plus the amount that flows in over the side of the grate through the slats/bars. The analysis shall include a 35% clogging factor. The use of formulas for side flow interception for grate inlets found in FHWA Hydraulic Engineering Circular No. 22 (HEC-22) will be accepted. b. The following procedure is most accurate when velocities are in the range of 3 to 5 feet/second at a 2% or 3% longitudinal slope. For instances where the velocity is found to exceed 5 feet/second, additional intermediate inlets can be added, contributing basins redefined, and the associated velocities recalculated. While adding inlets is one solution to reducing the velocity, more information may be found regarding the effect of side flow by consulting the HEC-22 Circular, Section 4.4 Drainage Inlet Design. Note that commercially available software may be used to determine grate inlet capacity. C. The capacity of a grate inlet on a continuous grade may be calculated using the procedure outlined below. Figure 24 identifies key parameters. Example calculations for grate inlets on a continuous grade for a uniform gutter section are provided in APPENDIX G2. i Determine the runoff from the contributing basin at the high point to the first inlet. This is the amount of runoff that could be intercepted by the first inlet. Depth (d) cannot exceed the top of the curb. ii Select an inlet and note the grate width (GW) in the calculations (refer to Table 23). Figure 24 - Typical Grate Inlet Cross -Section 153 CHAPTER 4 — STORMWATER DESIGN SECTION 4.8.7C Table 23 - Allowable Width and Perimeter for Grate Capacity Analvsis Structure Type Allowable Width on a Continuous Grade (feet) Curb Inlet[ 1 ] 1.41 Roll -Over Grate Inlet[21 1.43 iii Analyze the most upstream inlet. The width of flow (T) is calculated using the procedure described in 4.8.6. Verify that T is within the allowable limit (see Table 21), and then determine the amount of flow intercepted by the grate (basin flow — bypass flow). iv The inlet bypass flow on a continuous grade is computed as follows: 8 Equation 29 QBP = Q (T-wG)s T I Based on Olympic Foundry SM49B 2 Based on Olympic foundry SM44 A) Where: I) QBP = portion of flow outside the grate width (cfs); II) Q = total flow of gutter approaching the inlet (cfs); III) T = spread, calculated from the gutter section upstream of the inlet (feet); and IV) WG= width of grate inlet as measured perpendicular to the direction of flow (feet), see Table 23. 154 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.1 A v The velocity shall not exceed 5 feet/second. The velocity of flow directly over the inlet is calculated as follows: Equation 30 Vl = Q-QBP WG*[d—(0.5*Wc*Sx)l A) Where: I) VI = velocity over the inlet (feet/second); II) Sx = cross slope (feet/foot); and, III) d = depth of flow at the face of the curb (feet), given by: d = (T)(Sx ) B) If the non -flooded road width does not meet the minimum criteria, an additional inlet should be placed at an intermediate location and the procedure repeated. C) If the velocity exceeds 5 feet/second then side flow shall be considered using the method outlined in HEC-22 Circular, Section 4.4 Drainage Inlet Design. vi The analysis is then repeated with the next inlet. The bypass flow (QBP) from the previous inlet shall be added to the flow from the contributing basin to determine the total flow to the inlet at the station being analyzed. vii The last inlet may require an adjustment of spacing (usually smaller spacing) in order to prevent a bypass flow to the project boundaries. 1I. Other Drainage Inlets a. The design for the drainage inlets other than Grate Inlets, Continuous Grade described above shall be calculated using the procedure outlined in FHWA Hydraulic Engineering Circular No. 22 (HEC-22). Example calculations can also be found in the 2008 Spokane Regional Stormwater Manual, Chapter 8. 4.9 EROSION AND SEDIMENT CONTROL DESIGN 4.9.1 INTRODUCTION A. Stormwater Management is increasingly important for the purpose of maintaining clean water and preserving waterbodies such as streams, rivers, and lakes. The City of Kalispell's Stormwater Management Ordinance 1600 went into effect May 2, 2007, as mandated under the Federal Clean Water Act (CWA) and the Montana Pollution Discharge Elimination (MPDES) regulation. These regulations are designed to improve water quality in waterbodies by reducing the amount of pollutants that stormwater collects and carries into storm conveyance systems. 155 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.1 B B. This section lists the steps for developing a construction site Stormwater Management Plan (also known as an Erosion and Sediment Control Plan (ESQ. Controlling erosion and preventing sediment and other pollutants from leaving the project site during construction can be achieved by implementing the best management practices (BMPs) identified in this section. The ESC plan shall outline specific construction BMPs for a project site to avoid adverse stormwater impacts from construction activities on water resources, roads, drainage facilities, surrounding properties and other improvements. C. Potential impacts due to erosion and sedimentation include: I. Sediment accumulation in culverts, storm drains and open channels, resulting in decreased capacities and the potential for increased flooding and increased maintenance frequency; II. Sedimentation of storage ponds and swales, resulting in decreased infiltrative and storage capacity, and the potential for increased flooding and failure; III. Destruction of vegetation, topsoil and seeds, making re-establishment of vegetation difficult; IV. Increased turbidity, reducing water quality in water bodies; and, V. Air pollution due to fugitive dust. D. Implementation of an effective construction site stormwater management plan may help to reduce these potential impacts as well as other unforeseen environmental impacts and associated costs. 4.9.2 APPLICABILITY A. A City Stormwater Management Plan for construction sites is required for land - disturbing activities which include, but are not limited to, excavation, planting, tilling, and grading, which disturbs the natural or improved vegetative ground cover so as to expose soil to the erosive forces of rain, stormwater runoff or wind. All installations and maintenance of franchise utilities such as telephone, gas, electric, etc., shall be considered land disturbing activities. B. The following land -disturbing activities require a City Stormwater Management Permit: I. Any activity where the total volume of material disturbed, stored, disposed of or used as fill exceeds five (5) cubic yards; or, II. Any activity where the area disturbed exceeds one thousand (1,000) square feet provided it does not obstruct a watercourse, and is not located in a floodplain. C. The Stormwater Management Plan shall adhere to Ordinance 1600 and be submitted prior to any land -disturbing activity. The following is a summarization of the standards set in Ordinance 1600. 156 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3A 4.9.3 EROSION AND SEDIMENT CONTROL (ESC) PLAN A. INTRODUCTION I. A professional with a good working knowledge of hydrology and ESC practices, must prepare the ESC plan. For projects greater than 1 acre requiring a state SWPPP, the ESC must be prepared by a certified SWPPP Administrator. A copy of the ESC plan must be located on the construction site or within reasonable access to the site. As site construction progresses, the ESC plan may require modification to reflect changes in site conditions. II. The ESC plan must accompany the road and drainage plans, grading plan, or permit request and should be integrated into the grading plan whenever possible. It must contain sufficient information to demonstrate to the City Engineer that potential problems associated with erosion, sediment, and pollution have been adequately addressed for the proposed project. The drawings and notes should be clear and concise and describe when and where each BMP is to be implemented. B. MINIMUM REQUIREMENTS FOR ESC PLANS I. At a minimum, all ESC plans must be legible, reproducible and on good quality, and must contain the following information: a. Description of project, list of the locations of any existing water bodies and/or stormwater systems; b. Summary description of ESC BMPs utilized; and, Construction Sequence. C. BEST MANAGEMENT PRACTICES FOR ESC PLANS I. BMPs must be used to comply with the requirements of this section. It is not the intent of this section to limit innovative or creative efforts to effectively control erosion and sedimentation. Experimental ESC management practices to improve erosion control technology and meet the purpose and intent of this section are encouraged as a means of solving erosion and sedimentation problems. It is important to note that not only do new facilities and off -site properties need to be protected from erosion and sedimentation, but existing facilities on -site or downstream also need to be evaluated and protected if there is potential for damage due to lack of erosion control. II. As the season and subsequent site conditions dictate, alterations to existing ESC BMPs may be warranted or additional ESC measures may be required. Note that items below are considered suggested general erosion and sedimentation control notes and guidelines. The notes can be used on the ESC plan, when applicable to a given project site. 157 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C III. BMPs referenced in this section are from the Montana Department of Transportation Erosion and Sediment Control Best Management Practices Manual (MDT ESC Manual). Detailed examples and descriptions of these BMPs are included in MDT ESC Manual. At a minimum, the following items shall be addressed in the ESC plan: a. Construction Sequence i Install temporary ESC BMPs; constructing sediment trapping BMPs as one of the first steps prior to grading; ii Clear, grub and rough grade for roads, temporary access points and utility locations; iii Stabilize roadway approaches and temporary access points with the appropriate construction entry BMP; iv Temporarily stabilize, through re -vegetation or other appropriate BMPS, lots or groups of lots in situations where substantial cut or fill slopes are a result of the site grading; v Construct roads, buildings, permanent stormwater facilities, i.e., inlets, ponds, UIC facilities, etc.; vi Protect all permanent stormwater facilities utilizing the appropriate BMPs; vii Install permanent ESC controls, when applicable; and, viii Remove temporary ESC controls when: A) Permanent ESC controls, when applicable, have been completely installed; B) All land -disturbing activities that have the potential to cause erosion or sedimentation problems have ceased; and, C) Vegetation had been established in the areas noted as requiring vegetation on the accepted ESC plan on file with the City Engineer. b. Clearing Limits Distinctly mark all clearing limits, both on the plans and in the field— taking precaution to visibly mark separately any flood plain areas, and trees that are to be preserved —prior to beginning any land - disturbing activities, including clearing and grubbing; and, ii If clearing and grubbing has occurred, there is a window of 14 days in which construction activity must begin, otherwise the cleared area must be stabilized. 158 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C iii Suggested BMPs: A) Preserving Natural Vegetation B) Flood Plain Delineation C) Buffer Zones D) High Visibility Plastic or Metal Fence E) Stake and Wire Fence C. Construction Access Route i Limit access for construction vehicles to one route whenever possible; ii Stabilize the construction access routes to minimize the tracking of sediment onto roadways; iii Install temporary vehicle tracking approach at site entrance locations; iv Inspect all roadways, at the end of each day, adjacent to the construction access route. If it is evident that sediment has been tracked offsite and/or beyond the roadway approach, removal and cleaning is required; v If sediment removal is necessary prior to street washing, it shall be removed by shoveling or sweeping and transported to a controlled sediment disposal area; vi If street washing is required to clean sediment tracked offsite, once sediment has been removed, street wash wastewater shall be controlled by pumping back on -site or otherwise prevented from discharging into systems tributary to waters of the state; and, vii Locate wheel washes or tire baths, if applicable to ESC plan, on site. Dispose of wastewater into a separate temporary on -site treatment facility in a location other than where a permanent stormwater facility is proposed. viii Suggested BMPs: A) Stabilized Construction Entrance/Exit B) Stabilized Construction Roadways C) Entrance/Outlet Tire Wash D) Rumble Strip/Cattle Guard E) Construction Road/Parking Area Stabilization 159 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C d. Install Sediment Controls i Retain the duff layer, native topsoil, and natural vegetation in an undisturbed state to the maximum extent practical; ii Pass stormwater runoff from disturbed areas through a sediment pond prior to leaving a construction site or discharging to an infiltration facility; iii Keep sediment on the project site, to the maximum extent practical, in order to protect adjacent properties, water bodies, and roadways; iv Stabilize earthen structures such as dams, dikes, and diversions with either quarry spalls, seed or mulch, or a combination thereof; v Locate sediment facilities such that they will not interfere with natural drainage channels or streams; and, vi Inspect sediment control BMPs bi-weekly at a minimum, daily during a storm event, and after any discharge from the site (stormwater or non-stormwater). The inspection frequency may be reduced to once a month if the site is stabilized and inactive. vii Suggested BMPs: A) Check Dams B) Street Sweeping and Vacuuming C) Silt Fence D) Vegetated Strip E) Straw Wattles (fiber rolls) F) Sediment Trap G) Desilting Basin e. Soil Stabilization Select appropriate BMPs to protect the soil from the erosive forces of raindrop impact, flowing water and wind, taking into account the expected construction season, site conditions and estimated duration of use; ii Control fugitive dust from construction activity in accordance with state and local air quality Ordinances; iii Stabilize exposed unworked soils (including stockpiles), whether at final grade or not, within 14 days; iv Soils must be stabilized and seeded by October 15 of every year; and, v Stabilization practices include, but are not limited to, temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabric and mats, soil application of polyacrylamide (PAM) and the early application of gravel base on areas to be paved, and dust control. 160 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C vi Suggested BMPs: A) Scheduling B) Preservation of Existing Vegetation C) Temporary Seeding D) Erosion Seeding E) Mulching (straw, wood) F) Geotextiles, Plastic Covers, and Erosion Control Nets/Blankets/Mats G) Sodding H) Topsoiling I) Polyacrylamide (PAM) for Soil Erosion Protection J) Surface Roughening K) Gradient Terraces L) Dust Control f. Protection of Inlets i Protect inlets, drywells, catch basins and other stormwater management facilities from sediment, whether or not facilities are operable, so that stormwater runoff does not enter the conveyance system (both on and off site) without being treated or filtered to remove sediment; ii Keep roads adjacent to inlets clean; sediment and street wash water shall not be allowed to enter the conveyance system (both on and offsite) without prior treatment; and, iii Inspect inlets weekly at a minimum and daily during storm events. Inlet protection devices shall be cleaned or removed and replaced before 6 inches of sediment can accumulate. iv Suggested BMPs: A) Inlet protection -products manufactured for grate inlet protection. Placing silt fence fabric or other drain fabric over an inlet grate is an unacceptable practice and will not be allowed. g. Runoff from Construction Sites i Protect down -gradient properties, waterways, and stormwater facilities from possible impacts due to increased flow rates, volumes, and velocities of stormwater runoff from the project site that may temporarily occur during construction; ii Runoff from the construction site through the detention/retention 161 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C iii Storage pond or swales shall be addressed in the construction sequence. No sediment laden water shall pass through the flow control system and discharge to an offsite storm conveyance system; iv Construct stormwater control facilities (detention/retention storage pond or swales) before grading begins. These facilities shall be operational before the construction of impervious site improvements; and; v Protect permanent infiltration facilities that are used for flow control during construction. vi Suggested BMPs: A) Scheduling B) Sediment Trap C) Temporary Sediment Pond D) Temporary/Permanent Seeding h. Washout Site for Concrete Trucks and Equipment i Designate the location of a slurry pit where concrete trucks and equipment can be washed out. Slurry pits are not to be located in or upstream of a swale, drainage area, stormwater facility or water body, or in an area where a stormwater facility is existing or proposed. ii Suggested BMP: A) Concrete Waste Management i. Material Storage/Stockpile i Identify locations for storage/stockpile areas, within the proposed ESC plan boundaries, for any soil, earthen and landscape material that is used or will be used on -site; ii Stockpile materials (such as topsoil) on -site, keeping off roadway and sidewalks; and, iii Maintain on -site, as feasible, items such as gravel and a roll of plastic, for emergency soil stabilization during a heavy rain event, or for emergency berm construction. iv Suggested BMP: A) Stockpile Management B) Material Use C) Material Delivery and Storage 162 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.3C j. Cut and Fill Slopes i Consider soil type and its erosive properties; ii Divert any off -site stormwater run-on or groundwater away from slopes and disturbed areas with interceptor dikes, pipes or temporary swales. Off- site stormwater shall be managed separately from stormwater generated on -site; iii Reduce slope runoff velocities by reducing the continuous length of slope with terracing and diversion, and roughening the slope surface; iv Place check darns at regular intervals within ditches and trenches that are cut into a slope; and, v Stabilize soils on slopes, where appropriate. vi Suggested BMPs: A) Temporary and Permanent Seeding B) Surface Roughening C) Gradient Terraces D) Interceptor Dike and Swale E) Grass -Lined Channels F) Pipe Slope Drains G) Level Spreader H) Check Dams 1) Triangular Silt Dike (Geotextile-Encased Check Dam) k. Stabilization of Temporary Conveyance Channels and Outlets i Stabilize outlets of all conveyance systems adequately to prevent erosion of outlets, adjacent streambanks, slopes and downstream reaches. ii Suggested BMPs: A) Channel Lining B) Outlet Protection 1. Control of Pollutants Other Than Sediment on Construction Sites i Control on -site pollutants, such as waste materials and demolition debris, in a way that does not cause contamination of stormwater or groundwater. Woody debris may be chopped or mulched and spread on - site; ii Cover, contain and protect all chemicals, liquid products, petroleum products, and non -inert wastes present on -site from vandalism use secondary containment for on -site fueling tanks; 163 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.4A iii Conduct maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system repairs, solvent and de- greasing operations, fuel tank drain down and removal, and other activities that may result in discharge or spillage of pollutants to the ground or into stonmwater runoff using spill prevention measures, such as drip pans. Clean all contaminated surfaces immediately following any discharge or spill incident. If raining, perform on -site emergency repairs on vehicles or equipment using temporary plastic over and beneath the vehicle; and, iv Locate pH -modifying sources, such as bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and cutting, exposed aggregate processes, and concrete pumping and mixer washout waters, downstream and away from any stormwater facilities or location of proposed stormwater facilities. v Suggested BMPs: A) Concrete Waste Management B) Liquid Waste Management M. Permanent BMPs i Include permanent BMPs, if necessary, in the ESC plan to ensure the successful transition from temporary BMPs to permanent BMPs; and, ii Restore and rehabilitate temporary BMPs that are proposed to remain in place after construction as permanent BMPs. n. Maintenance of BMPs Inspect on a regular basis (at a minimum bi-weekly, and daily during/after a runoff producing storm event) and maintain all ESC BMPs to ensure successful performance of the BMPs. Conduct maintenance and repair in accordance with individual ESC BMPs outlined in this section; and, ii Remove temporary ESC BMPs within 30 days after they are no longer needed. Permanently stabilize areas that are disturbed during the removal process. 4.9.4 STORMWATER MANAGEMENT PERMIT A. PERMIT RESPONSIBILITY I. Greater Than or Equal to an Acre a. Construction site disturbing greater than or equal to an acre in the City Limits are generally required to follow two sets of guidelines. The guidelines are from the Montana Department of Environmental Quality (MDEQ) and the City of Kalispell. In order for a construction project to begin follow the steps below regarding stormwater permits and requirements. 164 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.4A MDEQ Requirements for the General Permit for Stormwater Discharges Associated with Construction Activity (Permit MTR100000) A) Develop a Stormwater Pollution Prevention Plan (SWPPP) I) The SWPPP is a document that is developed to direct and assist operators in identifying sources of potential pollutants at the construction activity site and Best Management Practices (BMPs) to be used to help ensure pollutants do not impact receiving surface water through stormwater runoff. II) The SWPPP must contain a narrative description of the project and a drawing of the site with proposed improvements and BMPs. III) The plan is to be kept on site and available for inspection by MDEQ and the City of Kalispell. B) Review and submit a Notice of Intent (NOI) I) To obtain the forms necessary to complete the NOI refer to the MPDES General Permit for Stormwater Discharges Associated with Construction Activity, which can be downloaded from www.deq.state.mt.us. C) Provide a copy of the NOI, SWPPP, and approval letter to the City of Kalispell Public Works Department a minimum of 5 days prior to starting land disturbance activities. D) Post a copy of the complete NOI and SWPPP at the construction site until completion of construction activity. E) Implement SWPPP prior to beginning land disturbance activity. F) Inspect and maintain BMPs outlined in Permit MTR100000 G) At the completion of the project submit a Notice of Termination (NOT) following permit requirements. A copy of the NOT must be submitted to the City of Kalispell Public Works Department. 165 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.4A ii City of Kalispell Stormwater Management Permit Requirements A) Submit a complete Stormwater Management Permit Application to the City of Kalispell Public Works Department a minimum of five (5) days prior to land disturbance. • The permit application must have the following complete forms • Stormwater Management Permit Application Form • Stormwater Management GREATER Checklist (included in application packet) B) NOI, SWPPP, Site Map and approval letter from DEQ I) The permit fee of $45 for sites greater than or equal to one (1) acre is to be paid at the time the permit application is submitted. C) Inspect and Maintain BMPs I) The permittee(s) will be required to perform a site inspection every 14 days and after major storm events to ensure all BMPs have been constructed and are functioning properly. II) All inspections shall be documented in written form, kept on the project site, and made available for review and duplication by the City. D) All changes and notifications submitted to DEQ for the General Permit must also be submitted to the City. This includes notification of facility contact changes and changes to authorization. E) At the completion of the project, submit a copy of the Notice of Termination (NOT) to the City of Kalispell Public Works Office. II. Less Than an Acre a. Owners/operators of construction sites less than one (1) acre are required to apply for a City of Kalispell Stormwater Management Permit (SMP). The SMP requires submittals of an application form and a Stormwater Management Plan in compliance with the City of Kalispell's Stormwater Management Ordinance 1600. 166 CHAPTER 4 — STORMWATER DESIGN SECTION 4.9.4E b. The Stormwater Management Plan shall contain the following items; i A completed Stormwater Management Plan checklist which outlines the project site's Best Management Practices (BMPs) ii A short narrative explaining how the permittee(s) will implement BMPs described on the checklist iii A map of the construction site showing the locations of the BMPs The Stormwater Management Permit application must be submitted to the City of Kalispell Public Works Department a minimum of five days before construction begins. A fee of $10 for sites less than one (1) acre shall be paid at the time the permit application is submitted. B. MAINTENANCE RESPONSIBILITY I. The owner or owner agent is responsible to ensure that BMPs are used, maintained, and repaired so that the performance standards continue to be met. After all land -disturbing activity is complete and the site has been permanently stabilized, maintenance and the prevention of erosion and sedimentation is the responsibility of the property owner. C. INPECTIONS AND RECORDS I. Site Inspections a. The permittee(s) will be required to perform a site inspection every 14 days and after major storm events to ensure all BMPs have been constructed and are functioning properly. b. All inspections shall be documented in written form, kept on the project site, and made available for review by the City. II. Changes a. All changes and notifications submitted to DEQ for the General Permit for Stormwater Discharges Associated with Construction Activity (Permit MTR100000) must also be submitted to the City. This includes notification of facility contact changes and changes to authorization. D. ENFORCEMENT AND APPEALS PROCESS If any violation is found, a notice will be issued to the Responsible Party. The notice will state the nature of the alleged violation(s), the action required to fix the violation(s), and a time limit to fix the violation(s). The City has the authority to issue a stop work order, clean the public way and bill the owner directly for the actual cost of cleanup plus a $200 administrative fee, and issuing a civil citation. Any person, firm, or corporation violating any of the provisions or terms of Ordinance 41600 of the City of Kalispell may be subject to penalties as a municipal infraction pursuant of Chapter 1, Article II of the Kalispell City Code. Each day of continued violation shall constitute a separate, additional offense. 167 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.1A 4.10 MAINTENANCE, PARCELS, AND EASEMENTS 4.10.1 MAINTENANCE A. INTRODUCTION I. Proper maintenance of stormwater facilities leads to better performance and increases the life of the facility. Insufficient maintenance of stormwater control facilities can lead to poor performance, shortened life, increased maintenance and replacement costs, and property damage. II. The City of Kalispell maintains the stormwater system structures located within the public road right of way. Drainage parcels created by public projects will be maintained by the City of Kalispell. The project owner shall provide for the perpetual maintenance of all elements of the stormwater system located outside the public right of way. III. The high -frequency maintenance of vegetated cover, turf grass, and other landscaping within the public right of way and within easements that accommodate public road runoff is the responsibility of the adjacent property owner. When applicable, the following maintenance -related items shall be submitted with the Drainage Submittal (refer to Section 4.3) for all projects: a. A copy of the conditions, covenants and restrictions (CC&Rs) for the homeowners' association (HOA) in charge of operating and maintaining all elements of the stormwater system; b. A Financial Plan outlining the funding mechanism for the operation, maintenance, and repair of the private stormwater system, including contingencies; and, C. An Operations and Maintenance (O&M) Manual. IV. APPENDIX HI outlines facility maintenance recommendations and frequencies. I. All projects that meet the regulatory threshold and that propose drainage facilities or structures shall comply with the Basic Requirement for operation and maintenance. See Section 4.2.1 C for regulatory threshold descriptions. C. HOMEOWNERS' AND PROPERTY OWNERS' ASSOCIATIONS I. For privately maintained stormwater systems in residential neighborhoods, a homeowner's association shall be formed to maintain the facilities located outside of the public right of way. 168 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.1D II. A draft copy of the CC&Rs for the HOA in charge of operating and maintaining the facilities associated with the stormwater system shall be submitted as part of the Drainage Submittal review package. The CC&Rs shall summarize the maintenance and fiscal responsibilities of the HOA and reference the O&M Manual. HOA dues shall provide funding for the annual operation and maintenance and replacement costs of all facilities associated with the stormwater system. III. For commercial/industrial and multi -family residential developments with joint stormwater systems and multiple owners, a property owners' association (POA) or similar entity such as a business shall be formed, or a reciprocal -use agreement executed. IV. Homeowners' associations and property owners' associations are to be non- profit organizations. A standard business license is not acceptable for this purpose. D. OPERATION AND MAINTENANCE MANUAL I. For stormwater systems operated and maintained by a HOA or POA, an O&M Manual is required. The O&M Manual summarizes the tasks required to ensure the proper operation of all facilities associated with the stormwater system and must include, as a minimum: Description of the entity responsible for the perpetual maintenance of all facilities associated with the stormwater system, including legal means of successorship; b. A list of contact names, phone numbers, and address of the entity responsible for the perpetual maintenance of all facilities associated with the stormwater system; C. Description of maintenance tasks to be performed and their frequency; d. An inspection check list to be used for the annual maintenance inspections. Refer to APPENDIX H2 for an example checklist; e. A list of the expected design life and replacement schedule of each component of the stormwater system; and, f. A general site plan (drawn to scale) showing the overall layout of the site, all the facilities associated with the stormwater system, and their elevations. E. MAINTENANCE AGREEMENT The owner shall be responsible for the operation and maintenance of such measures outlined in the Operation and Maintenance Manual and shall pass such responsibility to any successor owner. Prior to the approval by the Public Works Department of the stormwater management design plan, each owner shall submit a Maintenance Agreement. The agreement shall be recorded in the office of the clerk and recorder for Flathead County, Montana. 169 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.1 F II. The stormwater Maintenance Agreement shall be in a form approved by the City, and shall, at a minimum meet the following required elements of the Maintenance Agreement: a. Designate Responsible Party Designate for the land development the owner, governmental agency, or other legally established entity (responsible party) which shall be permanently responsible for maintenance of the structural or non-structural measures required by the Manual. b. Pass Responsibility to Successors: Pass the responsibility for such maintenance to successors in title. Property Description: Provide a legal description for the property. d. Operation and Maintenance Manual: Ensure the continued performance of the maintenance obligation required by the Operation and Maintenance Manual. e. Signature: The agreement shall be signed and dated by the designated responsible party. III. The agreement shall be recorded in the office of the clerk and recorder for Flathead County, Montana and shall run with the land. IV. An example agreement is given in APPENDIX H3. F. FINANCIAL PLAN L A Financial Plan is required in order to provide the entity responsible for maintenance with guidance in regard to financial planning for maintenance and replacement costs. The Financial Plan shall include the following items: a. A list of all stormwater-related facilities and their expected date of replacement and associated costs; b. Sinking fund calculations that take into consideration probable inflation over the life of the infrastructure and estimates the funds that need to be set aside annually; and, C. A mechanism for initiating and sustaining the sinking fund account demonstrating that perpetual maintenance of all facilities associated with the stormwater system will be sustained. G. FAILURE TO MAINTAIN STORMWATER SYSTEMS I. If the required maintenance and repairs are not being performed and inhibit the intended function of the stormwater system the City may hire a contractor to perform the required maintenance and bill the HOA, POA, or responsible property owner. 170 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.1 H II. In the event the HOA, POA, or responsible property owner fail to perform the required maintenance and repairs to the stormwater facility and inhibit the intended function of the stormwater system, a stormwater maintenance district program may be formed in accordance with §7-12-4102 MCA incorporating all the lots with in a development. The taxes levied within the maintenance district shall be determined by the Public Works Department with approval by the Kalispell City Council. H. MAINTENANCE ACCESS REQUIREMENTS An access road is required when the stormwater system facilities/structures are located 8 feet or more from an all-weather drivable surface. When required, maintenance access roads shall meet the following minimum requirements: a. The horizontal alignment of all access roads shall be designed and constructed to accommodate the turning movements of a Single -Unit Truck (as defined by AASHTO Geometric Design of Highways and Streets, Exhibit 2-4, 2004 Edition). The minimum outside turning radius shall be 50 feet. The minimum width shall be 12 feet on straight sections and 15 feet on curves; b. Access roads shall consist of an all-weather, drivable surface: i Reinforced turf is an acceptable surface and shall be installed per manufacturer's specifications and recommendations. Turf Reinforcement Units: `GRASSPAVE 2', as manufactured by Invisible Structures, Inc. in an acceptable product or approved equivalent. C. Access roads shall be located within a 20-foot-minimum-width (or as required by the horizontal alignment requirements) parcel or easement, extending from a public or private road; d. Access roads shall have a maximum grade of 8 percent; e. A paved apron must be provided where access roads connect to paved public roads; and, II. The following access road requirements apply only when the City has assumed the responsibility of the maintenance and operation of the facilities, though it is recommended that access roads for privately maintained facilities also be designed to meet these criteria: a. If the maintenance access road is longer than 150 feet, a turn -around is required at or near the terminus of the access road. Turn-arounds are required for long, winding, or steep conditions, regardless of the length of the drive, where backing up would otherwise be difficult; and, b. Turn-arounds shall conform to the City's Standards for Design and Construction. 171 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.2A 4.10.2 PARCELS AND EASEMENTS A. INTRODUCTION I. Flow control and treatment facilities shall be located within an individual parcel. Stormwater facilities serving commercial projects do not generally require parcels or easements unless they serve more than one parcel. II. A stormwater facility, as defined for this section, is a natural drainage way, constructed conveyance, Swale, or flow control facility. It is acceptable for other types of drainage systems, such as a pipe, to be in a drainage easement. Other stormwater drainage systems in a drainage easement, such as pipes, shall not straddle private property lines. A drainage parcel for access, maintenance, operation, inspection and repair shall be dedicated to the entity in charge of the maintenance and operation of the stormwater system. A parcel will be dedicated when any of the following situations are present: a. Facilities associated with a stormwater system serving a residential development are located outside of the public right of way; b. Drainage ditches located in residential neighborhoods. The limits of the parcel may have to be delineated with a permanent fence when the ditch is located near property lines; or, C. A natural drainage way is present. II. Parcels shall be of sufficient width to provide access to, and maintain, repair or replace elements of the stormwater system without risking damage to adjacent structures, utilities and normal property improvements, and without incurring additional costs for shoring or specialized equipment. C. EASEMENTS A drainage easement for access, maintenance, operation, inspection and repair shall be granted to the entity in charge of the maintenance and operation of the stormwater system. The easement shall grant to the City of Kalispell the right to ingress/egress over the easement for purposes of inspection, maintenance or repair. If not in a parcel, the following infrastructure shall be placed within drainage easements: 172 CHAPTER 4 — STORMWATER DESIGN SECTION 4.10.2C a. Elements of a stormwater system, such as a pipe, located outside the public right of way. Easements for stormwater conveyance pipes shall be of sufficient width to allow construction of all improvements, including any associated site disturbances, and access to maintain, repair or replace the pipe and appurtenances without risking damage to adjacent structures or incurring additional costs for shoring or special equipment. i No storm pipe in a drainage easement shall have its centerline closer than 5 feet to a private rear or side property line. ii The storm drain shall be centered in the easement. iii The minimum drainage easement shall be 20 feet. iv The drainage easement shall not straddle lot lines. v The drainage easement shall be offset five (5) feet from sidewalk. b. For drainage ditches and natural drainage ways, the easement width shall be wide enough to contain the runoff from a 100-year 24-hour storm event for the contributing stonnwater basin. Constructed drainage ditches shall not straddle lot lines. Natural drainage ways (refer to Section 4.8.3I) located on lots larger than 1 acre may be placed in an easement; and, C. Easements for access roads and turnarounds shall be at least 20 feet wide. II. Easement documents shall be drafted by the project owner for review by the City Engineer and recorded by the project owner. III. Off -Site Easements a. When a land action proposes infrastructure outside the property boundaries, an off -site easement shall be recorded separately from plat documents, with the clerk and recorders reception number placed on the face of the plat. The easement language shall grant the City of Kalispell the right to ingress and egress for purposes of routine or emergency inspection and maintenance. The following shall be submitted to the City Engineer for review: i A legal description of the site stamped and signed by a surveyor; ii An exhibit showing the entire easement limits and easement bearings, stamped and signed by a surveyor; iii Proof of ownership for the affected parcel and a list of signatories; and, iv Copy of the draft easement. b. For plats and binding site plans, the off -site drainage facility shall be clearly identified on the plans and operation and maintenance responsibilities shall be clearly defined prior to acceptance of the project. 173 APPENDIX A - CHECKLIST FOR IDENTIFYING WETLANDS Checklist for Identifying Wetlands Site °Data,; Subdivision/Parcel: Completed by: Evaluation date: Site visit date: Location: Township Range Section (" ") Physical Address: The following questions should be answered prior to a site visit using publicly available tools. If the response to any of these questions is yes, it is possible that a wetland is present on the parcel and the Site Visit Survey portion of this checklist should be completed. If no "Yes" answers, wetlands may still be present and wetlands should still be considered during the site visit. Yes No ❑ ❑ 1. Does the parcel or any adjacent parcels include U.S. Fish and Wildlife Service National Wetland Inventory (NWI) mapped wetlands? Refer to U.S. Fish and Wildlife Service National Wetlands Inventory maps (http.1/www.fws.gov/n. 2. Does an aerial photo of the parcel or any adjacent parcels show surface ❑ El Geological Refer to current aerial photo of property and other maps including U.S. Geological Survey topographic maps and digital hydrography layers (http:/inhd.uscis ocovv/), ❑ ❑ 3. Is the parcel or any adjacent parcels located within the 100-year floodplain? Refer to current floodplain maps available through County floodplain administrators. 4. Are there any streams, canals, ditches, or drainages present on the parcel ❑ ❑ or any adjacent parcels? Refer to current aerial photo of property and other maps including U.S. Geological Survey topographic maps and digital hydrography layers (httpJ/nhd. usgs. gov/1. 5. Does the parcel or any adjacent parcels have hydric soils mapped? Referto ❑ ❑ the most current soil survey data available through the Natural Resources Conservation Service (hitp://soils.usda.gov�. 6. Is there documentation of shallow groundwater on the parcel, or any ❑ ❑ adjacent parcel? Refer to groundwater data sets available from County Environmental Health Departments. 174 Wetland Checklist Site -is it Suirvey Wetland Indicators The following questions are for use during a site visit and will help determine if a wetland may be present at the parcel and if it is likely to be regulated by federal, state or local laws or regulations. If you check `yes" for any wetland indicators below, a Wetland Assessment outlined in the Kalispell Stormwater Quality Management Plan is required. The assessment must be performed by a wetland expert. The Stormwater Quality Management Plan can be obtained from the Kalispell Public Works Department. Yes No Wetland Hydrology ❑ ❑ 7. Is standing or flowing water observed at the parcel during the growing season? ❑ ❑ 8. Is the soil waterlogged during the growing season? ❑ ❑ 9. Are there water marks on any trees, shrubs, fencelines, buildings, etc.? ❑ ❑ 10. Optional (if you have had wetland delineation training) are there any primary or secondary hydrology indicators present? Wetland Vegetation ❑ ❑ 11. Does the parcel have plant communities that commonly occur in areas having standing water for part of the growing season (e.g. cattail marshes, sedges, bulrush, willows)? ❑ ❑ 12. Are any of the plants shown in the guide to `Common Wetland Plants of Western Montana' present? ❑ ❑ 13. If the parcel has been cleared of vegetation or mowed, are there adjacent areas that have plant communities or wetland plants connected to the parcel? Wetland Soils ❑ ❑ 14. Does soil show any hydric indicators (consists of predominantly decomposed plant materials, thick layer of decomposing plant material on the surface, sulfur odor, or soil is bluish gray)? ❑ ❑ 15. Is there standing water or is the soil surface either saturated or inundated? ❑ ❑ 16. Are the soils wet at or near the surface during dry summer periods? 175 EA99Die 101K4 MQyV%R0DIW1111111110*1� Purpose The swale flood test verifies the path of flow into a swale and the drawdown time of a bio- infiltration swale. The flood test shall be conducted, when required, after the swale has been constructed and the vegetation has been established, i.e., is not in danger of being washed out when water is introduced into the Swale. Procedure l . Introduce clean water into the swale by directing the water (via hose from a hydrant or other clean water source) along the curb and gutter upstream of the swale inlet. 2. Raise the water level in the swale until it reaches 6 inches in depth (typically to the rim of the drywell or catch basin). Discontinue flow and note the time; this is the beginning of the flood test. 3. If the Swale is draining rapidly, the progress is observed, and when the swale is empty, the time is documented, and the flood test has ended. 4. If the Swale is not draining, measure the depth of water currently in the swale, documenting the time, and return to the swale site at a later time in order to verify that the Swale has completely drained within 72 hours. APPENDIX B2 — POND FLOOD TEST Purpose The Pond Flood Test Method verifies drawdown time of a stormwater disposal facility, such as a detention pond. The pond flood test shall be conducted, when required, after the pond has been constructed, and after vegetation has been established, i.e., is not in danger of being washed out when water is introduced into the pond. Procedure 1. Introduce clean water into the pond. Use some form of splash -guard or diffuser device to prevent surface erosion of the pond. 2. Raise the water level in the pond until it reaches operational depth ,i.e., to the invert elevation of the first outlet device (culvert, orifice, weir, etc.). Discontinue flow. 3. Document the time and measure the depth of water in the pond; this is the beginning of the pond flood test. 4. The pond's ability to drain is observed. If the pond appears to be emptying rapidly, as soon as the pond is empty, the time is documented, and the flood test has ended. 5. If the pond is not draining, or is draining very slowly, measure the depth of water currently in the pond, documenting the time, and return to the pond site at a later time in order to verify that the pond has completely drained within 72 hours. NOTE: Contact the City Engineer for specific requirements for this Test Method. Some ponds will be large enough that a pond flood test may not be the most efficient method of determining drawdown time or infiltrative ability. Consideration may need to be given to other types of infiltrative test methods, such as the double -ring infiltrometer test. 176 APPENDIX C — BMP T5.100 API (Baffle type) Separator Bay (Source Section 5.10.7 of the Stormwater Management Manual for Eastern Washington.) The design criteria for small drainages are based on the design velocity, oil rise rate, residence time, width, depth, and length considerations. As a correction factor, the American Petroleum Institute (API) turbulence criterion is applied to increase the length. Ecology is modifying the API criterion for treating stormwater runoff from small drainage areas (fueling stations, commercial parking lots, etc.) by using the design hydraulic horizontal velocity, Vs, for the design Vet ratio rather than the API minimum of Vh/Vt = 15. The API criterion appears applicable for greater than two acres of impervious drainage area. Performance verification of this design basis must be obtained during at least one wet season using the test protocol referenced in Section 5.12 for new technologies. The following is the sizing procedure using the modified API criterion: Determine the oil rise- rate, Vt, in cintsec, using Stoke's Law (Water Pollution Control Federation, 1985), or empirical determination, or 0.033 ft./min for 60OF oil. The application of Stoke's Law to site -based oil droplet sizes and densities, or empirical rise rate determinations recognizes the need to consider actual site conditions. In those cases the design basis would not be the 60 micron droplet size and the 0.033 Ninin. rise rate. # Stoke's Law equation for rise rate, Vt (cm/sec), Vt = g(ow-a,)D' /I 8,q,) Where.- g = gravitational constant (981 cm sect) D = diameter of the oil particle in cm Use oil particle size diameter D=60 microns; (0.006 cm) cyw =0.999 gm/cc. at 32°F a,,: Select conservatively high oil density, for example. if diesel oil @ a.= 0.85 gm/ec and motor oil @ a. = 0.90 can be present, then use cr. = 0.90 gnVec ,q,,r = 0.017921 poise, gm/cm-sec at Tw = 3rF (See .API Publication 421, February, 1990) # Use the following separator dimension criteria* 1990 US Army Corps of Engineem, 1,994) Separator width w = between 6 and 20 feet (WEF & ASCE, 1998; King County Surface Water Management, 1998) 1 177 APPENDIX C Depth to width ratio d/w = between 0.3 and 0.5 (API, 1990) For stormwater Inflow from drainages, less thin 2 acres: • Determine Vt and select depth and width of the separator section based on above criteria. • Calculate the minimum residence time (ti.) of the separator at depth (d): t. = d/Vt • Calculate the horizontal velocity of ft bulk. fluid, Vh, vertical cross - sectional area, A,, and actual design Vb[Vt (American Petroleum Institute, 1990, US Army Corps of Engineers, 1994). Vh � Q/dw � Q/A,� (VI, maximum at < 2.0 fi/min, American Petroleum Institute, 1990) Q = 2.15 times the water quality design flow rate in ftlYmin, at minimum residence time, tm V-D of the SWMMWW) API F factors range from 1,28-1.74. (American Petroleum Institute, 1999) # Calculate the minimum length of the separator section, I(s), using- I(s) = FQtd-,vd = F(VhIVOd. 1(t) = 1(f) + I(s) +,(a) l(t) = l(t)13 + 1(s) + l(t)/4 Where: l(t) = total length of 3 bays l(f) = length of forebay l(a) = length of afterbay a Calculate V = I(s)wd = FQtm, and Ah = wl(s) V = minimum hydraulic design volume Ah = minimum horizontal area of the separator 178 APPENDIX D APPENDIX D - FLOW SPREADER OPTIONS Flow spreaders function to uniformly spread flows across the inflow portion of water quality facilities. • Anchored plate (Option A) • Concrete sump box (Option B) • Notched curb spreader (Option C) • Through -curb ports (Option D) • Level spreader treanch (Option E) Options A through C and E can be used for spreading flows that are concentrated. Any one of these options can be used when spreading is required by the facility design criteria. Options A through C and E can also be used for unconcentrated flows, and in some cases must be used, such as to correct for moderate grade changes along a filter strip. Options D is only for flows that are already unconcentrated and enter a filter strip or continuous inflow biofiltration swale. Anchored plate (Option A) An anchored plate flow spreader shall be preceded by a sump having a minimum depth of 8 inches and minimum width of 24 inches. The top surface of the flow spreader plate shall be level, projecting a minimum of 2 inches above the ground surface of the water quality facility, or v-notched with notches 6 to 10 inches on center and 1 to 6 inches deep (use shallower notches with closer spacing). Alternative designs are allowed. A flow spreader plate shall extend horizontally beyond the bottom width of the facility to prevent water from eroding the side slope. The horizontal extent should be such that the bank is protected for all flows up to the 100-year flow or the maximum flow that will enter the WQ facility.Flow spreader plates shall be securely fixed in place. Flow spreader plates may be made of either wood, metal, fiberglass, reinforce plastic, or other durable material. Anchor posts shall be 4-inch square concrete, tubular stainless steel, or other material resistant to decay. Concrete sump box (Option B) The wall of the downstream side of a rectangular concrete sump box shall extend a minimum of 2 inches above the treatment bed. This serves as a weir to spread the flows uniformly across the bed. The downstream wall of a sump box shall have "wing walls" at both ends. Side walls and returns shall be slightly higher than the weir so that erosion of the side slope is minimized. 179 APPENDIX D Notched curb spreader (Option C) Concrete for a sump box can be either cast -in -place or precast, but the bottom of the sump shall be reinforced with wire mesh for cast -in -place sumps.Sump boxes shall be placed over bases that consists of 4 inches of crushed rock, 5/8-inch minus to help assure the sump remains level. Notched curb spreader sections shall be made of extruded concrete (or equivalent) laid side by side and level. Typically five "teeth" per four -foot section provide good spacing. The space between adjacent "teeth" forms a v- notch. Through -curb ports (Option D) Unconcentrated flows from paved areas entering continuous inflow biofiltration swales can use curb ports to allow flows to enter the swale. Curb ports use fabricated openings that allow concrete curbing to be poured or extruded while still providing an opening through the curb to admit water to the WQ facility. Openings in the curb shall be at regular intervals but at least every 6 feet (minimum). The width of each curb port opening shall be a minimum of 11 inches. Approximately 15 percent or more of the curb section length should be in open ports, and no port should discharge more than about 10 percent of the flow. Level Spreader Trench -pea gravel (Option E) The trench shall be a 2' by 2' trench filled with pea gravel. 180 Y-notched or level plate spreader EMEMEMM nrotaction at outfalls Extend into she to protect from the 100 year How or the Nghest flow entering water quality facility. r== PLAN VIEW NTS rock rip rap S. (min.) gravel layer ekisfinggrac* 24* ftlia 181 APPENDIX D FLOW SPPX"ER OPTION B: CONCRETE SUMP BOX Example of a concrete sump flow spreader used with a bilofiltration swale (may be used with other WQ facilities), inlet pi" A* side with vein q walls See note Swale bottom w i n PLAN VIEW NTS inlet pipe wing wall outline cfearance r (M concrete sump (4' wall thickness� Mote: Extend sides into slope. Height of 182 SECTION A -A NTS r (minj IM B N 7 !j FRONT VIEW A -A NTS =1 APPENDIX D PLAN VIEW NTS SECTION B reinforce as nemssary NTS reinforced concrete curb Z A44 Opening I" min, grass filter sirip 183 APPENDIX D FLOW SPREADER OPTION E: LEVEL SPREADER TRENCH I IW.-10MiIATiT CURB OUT RIPRAP iNFL,CYVV e (1 W DEPTH, CLASS I) W CURB CA1'i ._.' RIPRAP INFLOW (1 S' DEPTH. CLASS 1) • W+iPrr� FILTER s LEVEL SPREADER TRENCH (PEA. GRAVEL) 7 DEPTH LEVELSPRF—ADER NTS 184 APPENDIX E APPENDIX E - FILTER STRIPS USED FOR PRE-TREATMENT Bioretention areas may utilize a filter strip as a pre-treatment measure. The required length of the filter strip depends on the drainage area, imperviousness, and the filter strip slope. The table below provides sizing guidance for using filter strips for pre-treatment. Sizing of Filter Strips for Pre-treatment (Source: Adapted from Georgia Stormwater Management Manual) Parameter Impervious Areaslil Pervious Areas (Lawns, etc) Maximum inflow approach 35 75 75 100 length (feet) Filter strip slope (max = 5%) < 2% > 2% < 2% > 2% < 2% > 2% < 2% > 2% Filter strip minimum 10 15 20 25 10 12 15 18 length (feet)[31 Flow must enter the filter strip as sheet flow, designed to spread out over the width of the strip with a depth of I to 2 inches. An effective flow spreader is a pea gravel diaphragm at the top of the slope (ASTM D 448 size no. 6, 1/8" to 3/8"). The pea gravel diaphragm (a small trench running along the top of the filter strip) serves two purposes. First, it acts as a pre-treatment device, settling out sediment particles before they reach the treatment BMP. Second, it acts as a level spreader, maintaining sheet flow as runoff flows over the filter strip. Other types of flow spreaders include a concrete sill and curb stops. 1 75 feet maximum impervious area flow length to filter strip. 2 150 feet maximum pervious area flow length to filter strip. 3 At least 25 feet is required for minimum pre-treatment of 10% TSS removal. Fifty feet is required for 50% removal 185 APPENDIX E Grass Channels Used for Pretreatment: Bioretention areas may utilize a filter strip as a pre-treatment measure. The length of the grass channel depends on the drainage area, land use, and channel slope. To be used as a pretreatment measure, the grass channel must have a minimum length of 20 feet. The Table below provides minimum lengths for grass channels based on channel slope and percent imperviousness (of the contributing drainage area). Grass Channel Sizing Guidance (Source. Georgia Stormwater Management Manual) Parameter < 33%Impervious Between 34% and 66% Impervious < 67%Impervious Slope < 2% > 2% < 2% > 2% < 2% > 2% (max = 4%) Grass channel min. length (feet) 25 40 30 45 35 50 assumes 2-ft bottom width 186 APPENDIX F APPENDIX F — PLANTING GUIDELINES Planting Guidelines for: Detention Pond: Seed mixtures Common & Species Name Bulk Rate (lb/ac) % of Mix Component Bluebunch Wheatgrass - Psuedoroegneria spicata (Goldar) 8 32 Thickspike Wheatgrass — EI mus lanceolatus (Critana) 5 20 Rough Fescue Festuca scabrella 3 12 Idaho Fescue Festuca idahoensis (Joseph) 6 24 Prairie Junegrass Koeleria macrantha crastad 3 12 Grass Totals: t-2-5 100 Or Slender Wheatgrass EI mus trach caulus Revenue 4 10 Mountain Brome Bromus mar inatis (Bromar) 6 15 Annual Ryegrass Lolium multiflorum 6 15 Winter Wheat* 24 60 Cover Crop Totals; 1 40 1 100 GRAND TOTAL: 1 65 1 100 187 APPENDIX F Planting Guidelines for: Infiltration facilities, Detention facilities, Swales, and Ditches Common & Species Name % of Mix Component Perinnial Rye Grass 15 Intermediate Wheatgrass 46 Creeping Fescue 8 Tall Fescue 31 Total 100 W1 Common & Species Name % of Mix Component Tall or Meadow 68 Fescue Seaside/ Creeping 10 Bentgrass Meadow Foxtail 10 Alsike Clover 6 Redtop Bentgrass 6 Total 100 188 APPENDIX F Planting Guidelines for Wetponds: Wetland Grasses Common & Species Name % of Mix Component Redtop Bentgrass 35 Meadow Foxtail 35 Russian Wildrye 20 Red Fescue 7 Bridsfoot Trefoil 2 Blackeyed Susan 1 Total 100 Or Common & Species Name % of Mix Component Redtop Bentgrass 35 Red Fescue 35 Meadow Foxtail 30 Total 100 189 Emergent Wetland Plant Species Recommend for Wetponds Agropyron riparian Elymus trachycaulus Elymus lanceolatus Festuca idahoensis Elymus glaucus Elymus trachycaulus Leymus triticoides Pascopyrum smithii Carex utriculata/rostrata Carex nebrascensis Carex lanuginosa Eleocharis palustris Juncus balticus Juncus tenuis Scirpus actus Bechmania syzigachne Carex aquatilis Carex utriculata/rostrata Eleocharis palustris Glyceria striata Juncus ensifolius Juncus mertensiana Juncus tenuis Sagittaria latifolia Scirpus microcarpus Scirpus americanus Scirpus acutus Typha latifolia streambank wheatgrass 5 30 slender wheatgrass 6 20 thickspike wheatgrass 6 30 Idaho fescue 3 20 beaked sedge nebraska sedge wooly sedge creeping spiked rush baltic rush slender rush hard stemmed rush western slough grass water sedge beaked sedge creeping spiked rush fowl mannagrass 3 stamen/dagger leaf rush Merten's rush slender rush arrowhead small fruited bulrush olney's bulrush hardstem bulrush cattail 190 shrubs�Corn on Name Willows- with standing long inundation Salix dummondii Drummond willow Salix boothii Booth's willow Willows -requires longer dry period Salix exigua sandbar/coyote willow Salix bebbiana Bebb's willow Salix geyeriana Geyer's willow Moist upland shrubs -see also recommended species list from Native Plant Society Acer glabrum rocky mountain maple Amelanchier alnifolia serviceberry Cornus stolonifer Eleagnus commutata Prunus virginiana Ribes aurem Sambucus racemosa Moist to wet fortis Iris missouriensis Mimulus lewisii red osier dogwood silverberry chokecherry golden current elderberry Rocky Mountain iris red monkeyflower APPENDIX F Notes: Regional distributors for wetland planting are 1)Windriver Seeds, 2) Blackfoot Native Plants, 3) Native West, 4) Western Native Seeds, 5)Wind Flower Native Plants 191 APPENDIX G1- EXAMPLE CALCULATION: NON -FLOODED WIDTH (UNIFORM GUTTER SECTION) GIVEN APPENDIX G1 A crowned road with a uniform gutter section (as illustrated), assuming an equal flow rate on each side of the road. • Flow rate (Q) = 4.2 cfs • Gutter width (W) = 1.5 feet • Road/Gutter cross slope (SX) = 0.02feet/foot • Longitudinal slope (SL) = 0.01 feet/ft • Manning's friction coefficient, n = 0.016 • Road width (RW) = 30 feet CALCULATIONS 1. Calculate the spread (T) for half of the roadway using Equation 28. T 0375 (4.20.01) 9 0,375 T = _ =12.4 feet fh5 � .. � .. , O� 5+6 (.02)` � (0.01 2. Calculate the non -flooded width using the following relationship for crowned roadways, and then verify that the non -flooded width is within the allowable limit (refer to Table 21). Non -flooded width = 2[(1/2)(RW) + W —T)] = 2[(1/2)(30) + 1.5—12.4)] 8.2 feet < 12 feet FAIL* * Table 21 indicates that the minimum non -flooded width is 12 feet for roads. Therefore, the design fails to meet the required non -flooded road width criteria. The design will need to be altered, i.e., try an additional inlet placed at an intermediate location, contributing basins redefined, new flow rates calculated, and the above steps repeated. 192 APPENDIX G2 APPENDIX G2 - EXAMPLE CALCULATION: GRATE INLET CAPACITY (UNIFORM GUTTER SECTION) GIVEN A crowned private road with a uniform gutter section (as illustrated), assuming an equal flow rate on each side of the road. • Flow rate (Q) = 2.5 cfs • Gutter width (W) = 1.5 ft • Grate width (GW) = 1.67 feet • Road/Gutter cross slope (Sj = 0.02 feet/foot • Longitudinal slope (SL) = 0.03 feet/foot' • Manning's friction coefficient, n = 0.016 • Road width (RW) = 30 feet CALCULATIONS 1. Determine the runoff from the contributing basin at the high point to the first inlet; • For this example, the design flow rate (Q) is given as 2.5 cfs 2. Select an inlet and note the grate width. • For this example, the grate width (GW) is given as 1.67 ft 3. Calculate the spread (T) for half of the roadway using Equation 28. U 11 (2.5�j,0.016) 0.375 T=E , s _ (=8.3lfeet 0.56 ��;.��5`�" 0.56 (0.02Y-'-1(0.0.��e.� r 193 APPENDIX G2 4. Calculate the non -flooded width using the following relationship, and then verify that the non -flooded width is within the allowable limit (refer to Table 21): Non -flooded width = 2[(1/2)(RW) + W — T )] = 2[(1/2)(30)+ 1.5-8.31)] = 16.38 feet > 12 feet OK* * Table 21 indicates that the minimum non -flooded width is 12 feet for private roads. Therefore, design has met the required non -flooded road width criteria. 5. Calculate the inlet bypass flow using 6. Equation 29: • With 35% clogging factor, grate width (GW) = 1.67(1 - 0.35) = 1.09' 8 g 13 (T) — (GW ? = 2 5 8.31-1.C19 QBP = =1.72cfs (T) 8.31 1 Therefore the capacity of the inlet = 2.5 — 1.72 = 0.78 cfs 5. Verify that the velocity does not exceed 5 feet/second. The velocity of flow directly over the inlet is calculated using Equation 30 (where d = T Sx): Q QSP 2.5 —1.72 � 4 611tYs 5 feet/ TV) r� —,5 GFi feet/sec szd OK* **Refer to Section 4.8.7C for guidance when the velocity exceeds 5 feet/second. 7. The analysis is then repeated with the next inlet. The bypass flow (QBP) from the previous inlet shall be added to the flow from the contributing basin to determine the total flow (Q) to the inlet at the station being analyzed. 194 APPENDIX Hl APPENDIX Hl - FACILITY MAINTENANCE RECOMMENDATIONS The following are operation and maintenance tasks for Treatment BMPs and Flood Control Facilities and should be used to create the required Operation and Maintenance Manual. Maintenance of facilities is driven by annual inspections that evaluate the condition and performance of the stormwater facilities. Based on inspection results, specific maintenance tasks will be triggered. An annual maintenance inspection form for facilities can be accessed at CWP website: //www.cwp.org/Resource_Library/Center—Docs/SW/pcguidance/Tool6.pdf. A more detailed maintenance inspection form is also available from Appendix B of CWP (2004) and from the City of Kalispell Public Works Department. WET:POND MAINTENANCE First -Year Maintenance Operations Successful establishment of wet ponds requires that certain tasks be undertaken in the first year. • Initial inspections: For the first six months following construction, the site should be inspected at least twice after storm events that exceed a 1/2 inch. • Planting of Benches: The aquatic benches should be planted with emergent wetland species. • Spot Reseeding: Inspectors should look for bare or eroding areas in the contributing drainage area or around the pond buffer, and make sure they are immediately stabilized with grass cover. • Watering: Trees planted in the pond buffer need watering during the first growing season, In general, consider watering every three days for first month, and then weekly during first year (Apr — Oct), depending on rainfall Inspections and Routine Maintenance Tasks Maintenance of wet ponds is driven by annual inspections that evaluate the condition and performance of the facility (see Table below). Suggested Activity Measure sediment accumulation levels in forebay. Monitor the growth of wetland plant, tree and shrubs planted. Record species and approximate coverage, and note presence of any invasive plant species. Inspect the condition of stormwater inlets to the pond for material damage, erosion or undercutting. Inspect upstream and downstream banks for evidence of sloughing, animal burrows, boggy areas, woody growth or gully erosion that may undermine embankment integrity. Inspect the pond outfall channel for erosion, undercutting, rip -rap displacement, woody growth, etc. Inspect condition of principal spillway and riser for evidence of spalling, joint failure, leakage, corrosion, etc. Inspect condition of all trash racks, reverse sloped pipes or flashboard risers for evidence of clogging, leakage, debris accumulation, etc. Inspect maintenance access to ensure it is free of woody vegetation and check to see whether valves, manholes or locks can be opened and operated. Inspect internal and external pond side slopes for evidence of sparse vegetative cover, erosion or slumping, and repaired immediately. Note: For a more detailed maintenance inspection checklist, see Appendix B in CWP (2004) Stormwater Pond and Wetland Maintenance Guidebook. 195 APPENDIX H 1 Maintenance is needed so stormwater ponds continue to operate as designed on a long-term basis. Wet ponds normally have less routine maintenance requirements than other stormwater treatment options. Stormwater pond maintenance activities range in terms of the level of effort and expertise required to perform them. Routine stormwater pond maintenance, such as mowing and removing debris or trash, is needed several times each year (See Table below). More significant maintenance such as removing accumulated sediment is needed less frequently, but requires more skilled labor and special equipment. Inspection and repair of critical structural features such as embankments and risers, needs to be performed by a qualified professional (e.g., a structural engineer) that has experience in the construction, inspection, and repair of these features. The maintenance plan should clearly outline how vegetation in the pond and its buffer will be managed or harvested in the future. Periodic mowing of the stormwater buffer is only required along maintenance rights -of -way and the embankment. The remaining buffer can be managed as a meadow (mowing every other year) or forest. The maintenance plan should schedule a shoreline cleanup at least once a year to remove trash and floatables. Typical Wet Pond Maintenance Tasks and Frequency Maintenance Items Frequency • Pond buffer reinforcement plantings and planting One time - After First Year of aquatic benches. • Mowing — twice a year. Quarterly or After Major Storms • Remove debris and blockages. (> 1 inch) • Repair undercut, eroded, and bare soil areas. • Shoreline cleanups to remove trash, debris and floatables. Annual • Full maintenance inspection. • Open up riser to access valves. • Repair broken mechanical components if needed. • Forebay Sediment Removal. 5-7 years • Repair pipes, riser andspillway where needed. 5-25 years 196 APPENDIX H1 INFILTRATION MAINTENANCE Maintenance Inspections Annual site inspections are critical to the performance and longevity of infiltration practices, particularly for small-scale and conventional infiltration practices. Maintenance of infiltration practices is driven by annual inspections that evaluate the condition and performance of the practice (see Table below). Ongoing Maintenance Effective long-term operation of infiltration practices requires a dedicated and routine maintenance inspection schedule with clear guidelines and schedules, as shown in the Table below. Where possible, facility maintenance should be integrated into routine landscaping maintenance tasks. Suggested Activity The drawdown rate should be measured at the observation well for three days following a storm event in excess of 0.5 inch in depth. If standing water is still observed in the well after three days, this is a clear sign that that clogging is a problem. Check inlets, pretreatment cells and any flow diversion structures for sediment buildup and structural damage. Note if any sediment needs to be removed. Inspect the condition of the observation well and make sure it is still capped. Check that no vegetation forms an overhead canopy that may drop leaf litter, fruits and other materials that could clog the device. Evaluate the vegetative quality of the adjacent grass buffer and do spot reseeding if cover is less than 90%. Generally inspect the upland CDA for any controllable sources of sediment or erosion. Look for weedy growth on rock surface that might indicate sediment deposition or clogging. Inspect maintenance access to ensure it is free of woody vegetation and check to see whether valves, manholes or locks can be opened and operated. Inspect internal and external infiltration side slopes for evidence of sparse vegetative cover, erosion or slumping, and repaired immediately. 197 APPENDIX H 1 Typical Maintenance Activities for Infiltration Practices Activity Schedule • Replace pea gravel/topsoil and top surface filter As needed fabric (when clogged). • Mow grass filter strips as necessary and remove clippings. • Ensure that contributing area, practice and inlets Quarterly are clear of debris. • Ensure that the contributing area is stabilized. • Remove sediment and oil/grease from pretreatment devices, as well as overflow structures. • Repair undercut and eroded areas at inflow and outflow structures. • Check observation wells following 3 days of dry Semi-annual Inspection weather. Failure to percolate within this time period indicates clogging. • Inspect pretreatment devices and diversion structures for sediment build-up and structural damage. • Remove trees that start to grow in the vicinity of the trench. • Clean out accumulated sediments from the Annually pretreatment cell 198 APPENDIX H1 POND MAINTENANCE Maintenance Inspections Maintenance of ED ponds is driven by annual inspections that evaluate the condition and performance of the facility (see Table below). Based on inspection results, specific maintenance tasks will be triggered. Common Maintenance Issues Ponds are prone to a high clogging risk at the low flow orifice. These aspects of pond plumbing should be inspected at least twice a year after initial construction. The constantly changing water levels in ponds make it difficult to mow or manage vegetative growth. The bottom of ponds often become soggy, and water -loving trees such as willows may take over. The maintenance plan should clearly outline how vegetation in the pond and its buffer will be managed or harvested in the future. Periodic mowing of the stormwater buffer is only required along maintenance rights -of -way and the embankment. The remaining buffer can be managed as a meadow (mowing every other year) or forest. The maintenance plan should schedule a shoreline cleanup at least once a year to remove trash and floatables that tend to accumulate in the forebay and on the bottom of ponds. Frequent sediment removal from the forebay or sump area is essential to maintain the function and performance of a pond. Maintenance plans should schedule cleanouts every 5-7 years, or when inspections indicate that 50% of forebay or smp area capacity has been lost. Suggested Annual Maintenance Inspection Activity Measure sediment accumulation levels in forebay. Monitor the growth of wetlands, trees and shrubs planted. Record species and approximate coverage, and note presence of any invasive plant species. Inspect the condition of stormwater inlets to the pond for material damage, erosion or undercutting. Inspect upstream and downstream banks for evidence of sloughing, animal burrows, boggy areas, woody growth or gully erosion that may undermine embankment integrity. Inspect pond outfall channel for erosion, undercutting, rip -rap displacement, woody growth, etc. Inspect condition of principal spillway and riser for evidence of spalling, joint failure, leakage, corrosion, etc. Inspect condition of all trash racks, reverse sloped pipes or flashboard risers for evidence of clogging, leakage, debris accumulation, etc. Inspect maintenance access to ensure it is free of woody vegetation and check to see whether valves, manholes or locks can be opened and operated. Inspect internal and external pond side slopes for evidence of sparse vegetative cover, erosion or slumping, and repaired immediately. Note: For a more detailed maintenance inspection checklist, see Appendix B in CWP(2004) Stormwater Pond and Wetland Maintenance Guidebook. 199 APPENDIX H 1 DRY SWALE MAINTENANCE Maintenance Inspections Inspections are used to trigger maintenance operations such as sediment removal, spot revegetation and inlet stabilization. Several key maintenance inspection points are detailed in the Table below. Ideally, inspections should be conducted in the spring of each year. Inspections/CleanupsSuggested Spring Maintenance Dry Swales Activity Add reinforcement planting to maintain 95% turf cover on vegetation density. Reseed any salt killed vegetation. Remove any accumulated sand or sediment deposits on the filter bed surface or in pretreatment cells. Inspect upstream and downstream of check dams for evidence of undercutting or erosion, and remove and trash or blockages at weep holes. Examine filter beds for evidence of braiding, excessive ponding or dead grass. Check inflow points for clogging and remove any sediment. Inspect side slopes and grass filter strips for evidence of any rill or gully erosion and repair. Look for any bare soil or sediment sources in the contributing drainage area and stabilize. Routine Maintenance and Operation Once established, dry swales have minimal maintenance needs outside of the spring clean up, regular mowing and pruning and management of trees and shrubs. The surface of the filter bed can become clogged with fine sediment over time, but this can be alleviated through core aeration or deep tilling of the filter bed. Additional effort may be needed to repair check dams, stabilize inlet point and remove deposited sediment from pretreatment cells. 200 APPENDIX H1 BIOSWALE AND GRASS CHANNEL MAINTENANCE Maintenance Inspections Annual inspections are used to trigger maintenance operations such as sediment removal, spot revegetation and inlet stabilization. Several key maintenance inspection points are detailed in the Table below. Ideally, inspections should be conducted in the spring of each year. Ongoing Maintenance Once established, bioswales and grass channels have minimal maintenance needs outside of the Spring clean up, regular mowing, repair of check dams and other measures to maintain the hydraulic efficiency of the channel and a dense, healthy grass cover. Suggested Spring Maintenance I nspections/Clean ups for Grass Channels Activity Add reinforcement planting to maintain 90% turf cover. Reseed any salt killed vegetation. Remove any accumulated sand or sediment deposits behind check dams. Inspect upstream and downstream of check dams for evidence of undercutting or erosion, and remove and trash or blockages at weep holes. Examine channel bottom for evidence of erosion, braiding, excessive ponding or dead grass. Check inflow points for clogging and remove any sediment. Inspect side slopes and grass filter strips for evidence of any rill or gully erosion and repair. Look for any bare soil or sediment sources in the contributing drainage area and stabilize immediately. BIORETENTION'' MAINTENANCE First -Year Maintenance Operations Successful establishment of bioretention areas requires certain tasks be undertaken in the first year. • Initial inspections: For the first six months following construction, the site should be inspected at least twice after storm events that exceed a half- inch • Spot Reseeding: Inspectors should look for bare or eroding areas in the contributing drainage area or around the bioretention area, and make sure they are immediately stabilized with grass cover • Fertilization: one-time, spot fertilization for initial plantings • Watering: Once a week during the first two months, and then as needed during first growing season (Apr — Oct), depending on rainfall • Remove and replace dead plants. Since up to ten percent of plant stock may die off in the first year, construction contracts should include a care and replacement warranty to ensure vegetation is properly established and survives during the first growing season following construction. The typical thresholds for replacement are 85% survival of plant material and 100% survival of trees. 201 APPENDIX H I Maintenance Inspections It is highly recommended that a spring maintenance inspection and cleanup be conducted at each bioretention area. The Table below presents some of the key maintenance problems. Suggested Spring Maintenance Inspections for Bioretention Activity Check to see if 90% mulch + vegetative cover has been achieved in the bed, and measure depth of remaining mulch. Check for sediment buildup at curb cuts, gravel diaphragms or pavement edges that prevent flow from getting into the bed. Check for any winter or salt -killed vegetation and replace with hardier species. Note presence of accumulated sand, sediment and trash in pretreatment cell or filter beds and remove. Inspect bioretention side slopes and grass filter strips for evidence of any rill or gully erosion and repair. Check bioretention bed for evidence of mulch flotation, excessive ponding, dead plants or concentrated flows and take appropriate remedial action. Check inflow points for clogging and remove any sediment. Look for any bare soil or sediment sources in the contributing drainage area and stabilize immediately. Routine and Non -Routine Maintenance Tasks Maintenance of bioretention areas should be integrated into routine landscaping maintenance tasks. If landscaping contractors will be expected to perform maintenance, their contracts should contain specifics on unique bioretention landscaping needs, such as maintaining elevation differences needed for ponding, proper mulching, sediment and trash removal, and limited use of fertilizers and pesticides. A customized maintenance schedule must be prepared for each bioretention facility, since the maintenance tasks will differ depending on the scale of bioretention, the landscaping template chosen, and the nature of surface cover. A generalized summary of common maintenance tasks and their frequency is provided in the Table below. 202 Suggested Bioretention Maintenance Tasks Frequency • Spring inspection and cleanup. Annual • Add reinforcement planting to maintain desired As needed vegetation density. • Spot weeding, erosion repair, trash removal, and Twice during growing season mulch raking. • Sediment removal in pretreatment cells and Once every two to three years inflow points. • Mowing of grass filter strips and bioretention turf At least four times a year cover. • Remove invasive plants using recommended As needed control methods. • Supplement mulch to maintain a 3 inch layer. Annual • Replace mulch layer. Every three years • Prune trees and shrubs. Annual • Stabilize contributing drainage area to prevent When needed erosion. The most common non -routine maintenance problem involves standing water. If water remains on the surface for more than 48 hours after a storm, adjustments to the grading may be needed or underdrain repairs may be needed. The surface of the filter bed should also be checked for accumulated sediment. Core aeration or deep tilling may relieve the problem. 203 APPENDIX H2 APPENDIX H2 — FACILITY INSPECTION CHECKLIST Stormwater Management Facility Inspection and Maintenance Log (Sample) Property Address: Inspection Date: Inspection Time: Inspected By: Date and Time of Last Rainfall: Type of Stormwater Management Facility: Location of Facility on Site (in relation to buildings or other structures): Water levels and observation (Oil sheen, Smell, Turbidity, etc.): Sediment accumulation and record of sediment removal: Condition of Vegetation (Height, survival rates, invasion species present, etc.) and record of replacement and management (mowing, weeding etc.) Condition of physical properties such as inlets, outlets, piping, fences, irrigation facilities, and side slopes. Record damaged items and replacement activities: Presence of insects or rodents. Record control activities: Identify safety hazards present. Record resolution activities: 204 APPENDIX H3 APPENDIX H3 - EXAMPLE MAINTENANCE AGREEMENT This Page Intentionally Left Blank 205 F.11mo ld01P.M:al Maintenance Agreement Responsible Party List the party that shall be permanently responsible for the maintenance of structural or non-structural measures required by the Operation Manual. (e.g. owner, governmental agency, or other legal established entity Designate personnel for inspection and maintenance: Name: Address: Contact Phone: Property Description List legal description of property: Cell: Operation and Maintenance Has the Operation and Maintenance Manual been created? ❑ Yes ❑ No Responsible Party shall ensure the continued performance of the maintenance obligation in accordance with the Operation and Maintenance Manual. Failure to Maintain Stormwater Systems If the required maintenance and repairs are not being performed and inhibit the intended function of the stormwater system the City may hire a contractor to perform the required maintenance and bill the HOA, POA, or responsible property owner. In the event the HOA, POA, or responsible property owner fail to perform the required maintenance and repairs to the stormwater facility and inhibit the intended function of the stormwater system, a stormwater maintenance district program may be formed in accordance with §7-12-4102 MCA incorporating all the lots within a development. The taxes levied within the maintenance district shall be determined by the Public Works Department with approval by the Kalispell City Council. By signing the Maintenance Agreement the Responsible Party shall assume full responsibility for the maintenance of the stormwater system. X Signature of Responsible Party Date 206 ABBEVIATIONS AND ACRONYMS ABBREVIATIONS AND ACRONYMS • AASHTO—American Association of State Highway and Transportation Officials • APWA—American Public Works Association • ARC —Antecedent Runoff Condition • ASTM—American Society for Testing and Materials • BMP—Best Management Practice • CC&R—Conditions, Covenants and Restrictions • efs—Cubic Feet per Second • CMP—Corrugated Metal Pipe • CN—Curve Number • ESC—Erosion & Sediment Control • FEMA—Federal Emergency Management Agency • FHWA—Federal Highway Administration • FIRM —Flood Insurance Rate Map • FS—Factor of Safety • GW—Grate Width • GSC—Geotechnical Site Characterization • HDPE—High-Density Polyethylene • HGL—Hydraulic Grade Line • HOA—Homeowner' s Association • IBC —International Building Code • Manual —City of Kalispell Stormwater Manual • MDT —Montana Department of Transportation • NDW—Natural Drainage Ways • NOAA—National Oceanic and Atmospheric Administration • NPDES—National Pollutant Discharge Elimination System • NRCS —Natural Resources Conservation Service • O&M —Operation and Maintenance • PAM—Polyacrylamide • POA—Property Owners Association • SCS—Soil Conservation Service • sf—Square Feet • TMDL—Total Maximum Daily Load • TPH—Total Petroleum Hydrocarbons • TSS—Total Suspended Solids • USGS—United States Geological Survey • WSDOT—Washington State Department of Transportation 207 GENERAL STANDARD DRAWINGS AND NOTES GENERAL STANDARD DRAWINGS AND NOTES 4" ASPHALT CRUSHED GRAVEL BASE. N y'^ 9"-12" SELECT— SUBBASE >,- `' M N. DETECTABLE WARNING TAPE, MIN. 3" p; 3" MINUS CRUSHED IN WIDTH, APWA COLORS SUBBASE MPWSS SECTION 02234 SLOPING, BENCHING, SHORING OR F a}:m PARAGRAPH 2.3 & 2.4 SUPPORT SYSTEMS IN THIS AREA TO CONFORM TO O.S.H A. REGULATIONS ¢ BEDDING, HAUNCHING & 14 GAUGE INSULATED SOLID CORE INITIAL BACKFILL COPPER TONING WIRE, TAPE TO TOP OF WATER MAIN EVERY 5 FT. JOINTS s SHALL BE MADE WITH MOISTURE DISPLACEMENT CONNECTORS 1.5" TO 3.5 " DIAMETER CRUSHED STONE TO STABILIZE UNSTABLE FOUNDATION ALL PIPE BEDDING AND TRENCH BACKFILL BEDDING, HAUNCHING & INITIAL BACKFILL SHALL BE COMPACTED TO 95% MAXIMUM DRY SHALL BE A CLEAN MEDIUM OR COARSE DENSITY IN ACCORDANCE WITH AASHTO T-99 SAND, OR CONTRACTOR SHALL SUBMIT ALL TRENCH CONSTRUCTION SHALL DOCUMENTATION THAT THE BEDDING, CONFORM TO CURRENT OSHA STANDARDS — HAUNCHING AND INITIAL BACKFILL WILL EXCAVATIONS MEET THE REQUIREMENTS FOR CLASS I MATERIALS DEFINED IN ASD 2321 INSTALL DETECTABLE WARNING TAPE AND TONER WITH A MAXIMUM PARTICLE SIZZE OF WIRE ON ALL WATER MAINS AND SEWER FORCE AND MEETING MIGRAA TION MAINS PER CITY STANDARDS. REQ" REQUIREMENTS QF THE SAME STANDARD (SECTION X.1.8) TYICAL UTILITY TRENCH SECTION DETAIL G. TRIVIEW 3 FACE FLEXIBLE MARKER POST GREEN IN COLOR AND MARKED SEWER, FOR SEWER, BLUE IN COLOR AND MARKED WATER FOR WATER n c�1 P AA QW a TL o P T E Q � � Mn R S R D E p R N l W E Q A B�oRe orcjoiNo IN THIS AREA E M E YY A UV H R a E O WORE omm THIS m Lw N R E IN AREA CALL [ j BsqofmDmm IN THIS AREA CALL NaI LOCATE TRACER WIRE THIS AREA C-LLL INSIDE MARKER POST AS APPLICABLE NOTES: 1, TRIVIEW, 3 FACE MARKER POSTS SHALL BE INSTALLED AT ALL BENDS, VALVES, MANHOLES, AND AT A SPACING OF EVERY 400 FEET FOR ALL WATER MAINS, SEWER MAINS, FORCEMAINS, AND STORM MAINS NOT LOCATED IN PAVED OR GRAVELED AREAS. 2. TRIVIEW, 3 FACE MARKER/TRACING STATIONS SHALL BE USED FOR MAINLINES AT INTERVALS OF EVERY 400 FEET. TRACER WIRE SHALL BE BROUGHT TO SURFACE INSIDE MARKING POST AT EACH POST. TYPICAL UNDERGROUND MARKER POST 208 SEWER SERVICE REQUIREMENTS; 1. SERVICE SHALL EXTEND PERPENDICULARLY FROM THE CONNECTION AT THE SEWER MAIN TO THE PROPERTY LINE. 2. SERVICE SHALL NOT PASS THROUGH ANY ADJACENT PRIVATE PROPERTY. 3.ONE SERVICE IS REQUIRED FOR EACH PARCEL OWNERSHIP, 4. SERVICE SHALL CONNECT AT THE MAIN IN THE DIRECTION OF FLOW. CITY RIGHT-OF-WAY CURB AND GUTTER -\ BOULEVARD GENERAL STANDARD DRAWINGS AND NOTES WATER SERVICE REQUIREMENTS: 1. METER PIT AND CURB STOP SHALL BE CENTERED IN THE BOULEVARD. IF METER PIT IS PLACED IN A DRIVEWAY, A HS20 TRAFFIC RATED RING AND COVER SHALL BE PROVIDED. 2. SERVICE SHALL EXTEND PERPENDICULARLY FROM THE CONNECTION AT THE WATER MAIN TO THE PROPERTY LINE. 3. SERVICE SHALL NOT PASS THROUGH ANY ADJACENT PRIVATE PROPERTY. 4. ONE SERVICE IS REQUIRED FOR EACH PARCEL OWNERSHIP. `-WATER METER PIT & CURB STOP w W FLOW SS SS DIRECTION TYPICAL UTILITY CONNECTIONS E WATER SYSTEM STANDARD DRAWINGS AND NOTES WATER SYSTEM STANDARD DRAWINGS AND NOTES WATER SYSTEM CONSTRUCTION NOTES: 1. THRUST BLOCKING IS REQUIRED AT ALL TEES, BENDS, CAPS, WATER MAIN VALVES, AND FIRE HYDRANTS 1N ACCORDANCE TO WITH MONTANA PUBLIC WORKS STANDARD SPECIFICATIONS. 2. WATER MAINS SHALL BE INSTALLED WITH 12 GAUGE SOLID CORE COPPER TONING WIRE WITH INSULATION RECOMMENDED FOR DIRECT BURY. THE TONER WIRE SHALL BE TAPED TO THE TOP OF THE WATER MAIN AT INTERVALS NO MORE THAN 5 FT. TONER WIRE SHALL BE EXTENDED TO THE SURFACE AT ALL VALVE LOCATIONS. TONER WIRE SHALL BE ROUTED UP THE EXTERIOR OF THE VALVE BOX TO WITHIN 8 INCHES OF THE SURFACE. THE CONTRACTOR SHALL DRILL A HOLE INTO VALVE BOX AND PLACE TONER WIRE IN INTERIOR OF VALVE BOX, TONER WIRE SHALL BE ACCESSIBLE WITH 3 FT OF EXCESS TO CONNECT WITH TONING EQUIPMENT, 3. ALL IRON FITTINGS AND METAL PARTS SHALL BE WRAPPED IN POLYETHYLENE ENCASEMENT. 4, CONCRETE COLLARS SHALL BE INSTALLED AT WATER VALVE BOX RISERS AND MANHOLE RING AND CASTINGS, SEE CITY OF KALISPELL STANDARDS FOR CONSTRUCTION. 5. TEMPORARY WATER SERVICES SHALL BE SUPPLIED DURING CONSTRUCTION WHEN WATER SERVICE WILL BE INTERRUPTED FOR MORE THAN FOUR (4) HOURS. A TEMPORARY WATER SERVICE PLAN SHALL BE SUBMITTED TO AND APPROVED BY THE CITY PRIOR TO THE COMMENCEMENT OF CONSTRUCTION. ALL TEMPORARY WATER SERVICES SHALL COMPLY WITH MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY DESIGN CIRCULAR 1, 6. CONTRACTOR SHALL PERFORM HYDROSTATIC LEAK TESTING IN ACCORDANCE WITH MONTANA PUBLIC WORKS STANDARD SPECIFICATIONS AS MODIFIED BY CITY SPECIAL PROVISION 02660. 7. ALL NEW, CLEANED OR REPAIRED WATER MAINS SHALL BE FLUSHED AND DISINFECTED IN ACCORDANCE WITH MONTANA PUBLIC WORKS STANDARD SPECIFICATIONS AS MODIFIED BY CITY SPECIAL PROVISION 02660. 8. THE CONTRACTOR SHALL BE RESPONSIBLE TO TAKE ALL BAC-T TESTS UNDER THE SUPERVISION OF CITY STAFF. AFTER SAMPLE COLLECTION THE CITY SHALL TAKE CHAIN OF CUSTODY OF SAMPLES AND DELIVER TO CERTIFIED ENVIRONMENTAL LAB. ALL TESTING SHALL BE AT THE EXPENSE OF THE CONTRACTOR. owl WATER SYSTEM CONSTRUCTION NOTES CENTER METER BOX IN BOULEVARD MUELLER H-10308 EXTENSION TYPE WITH ARC BASE. EQUIPPED W/ STATIONARY ROD AND PENTAGON BRASS PLUG. 9" RADIUS %' STEEL T-POST 4.50, 1 4.50, 1 5'1 10.00, MULLER/HUNNT THERMAL -COIL METER BOX WITH DUAL CHECK VALVE BACKFLOW PREVENTER, INSULATING PAD, AND CENTER LOCKING COMPOSITE LID. MUELLER SERIES 300 BALL STYLE CURB STOP VALVE NOTES: 1. 3/4" - 2" SERVICES SHALL BE INSTALLED WITH BR2 SERIES SERVICE SADDLES AND PE SERVICE LINE. 2. 4" AND LARGER SERVICES SHALL BE INSTALLED WITH A ROMAC SSTIII STAINLESS STEEL TAPING SLEEVE AND CLASS 150 PVC SERVICE LINE. rr.2 WATER SERVICE CONNECTION DETAIL 210 RED MUELLER SUPER CENTURION 250 FIRE HYD.--� WITH 5" STORZ ADAPTER TO FACE STREET 2 FT MIN TO MIN. } CY OF WASHED GRAVEL WEEP HOLE, MIN 2"-� ABOVE ALL BLOCKING CONCRETE THRUST BLOCK, MIN. 2 SO. FT. BEARING SURFACE WATER SYSTEM STANDARD DRAWINGS AND NOTES 2 FT MIN PROVIDE TRENCH BACKFILL PER CITY OF KALISPELL TYPICAL UTILITY TRENCH DETAIL 24" MIN CONCRETE BEARING MIN. 2'x2'x6" REPLACE EX. CURB TO MATCH EXISTING GRADE AND ALIGNMENT TYPICAL VALVE BOX COLLAR PER CITY OF KALISPELL CONSTRUCTION STANDARDS CAST IRON, 3 PIECE SUP VALVE BOX, TYLER 6865 SERIES, OR APPROVED EQUAL MARKED WATER 6" MUELLER RESILIENT WEDGE MJ GATE VALVE MJ x SWIVEL TEE, SEE PLAN FOR SIZE CONCRETE THRUST BLOCK PER SCHEDULE w rN. m z r a <tr• >,..z us to E 0 D CONCRETE THRUST BLOCK PER SCHEDULE 3__ STANDARD FIRE HYDRANT DETAIL 12" CONCRETE VALVE DETECTABLE WARNING TAPE, MIN. 3" IN WIDTH, APWA COLORS 5' MAX CL 150 WATER MAIN, SEE PLAN FOR SIZE, SHALL CONFORM TO AWWA C-900 OR AWWA C-905 FOR PIPE > 12" DIA SET VALVE BOX DEPTH IN ACCORDANCE TO MPWWS STANDARD DRAWING DRILL 1/2" DIA, HOLE, RETURN TONING WIRE TO INTERIOR OF VALVE BOX CAST IRON, 3 PIECE SUP VALVE BOX, TYLER 6865 SERIES, OR APPROVED EQUAL MARKED WATER MUELLER SERIES A-2360 RESILIENT WEDGE MJ GATE VALVE, WITH STANDARD SQ. WRENCH NUT SEE PLAN FOR SIZE CONCRETE THRUST BLOCK PER SCHEDULE :1 TYICAL MJ GATE VALVE SECTION DETAIL P.Y 211 WATER SYSTEM STANDARD DRAWINGS AND NOTES 45' MJ BEND WITH MEGALUG AND THRUST BLOCK, EXISTING SANITARY OR TYPICAL OF 4 STORM SEWER MAIN BACKFILL PER TYPICAL TRENCH SECTION CL 150 PVC WATER MAIN, SEE PLAN FOR SIZE �FQ- BACKFILL WITH z FLOWABLE FILL AS REQUIRED °.2 m h :a4 fxh v '-VERTICAL THRUST a� BLOCK WITH ANCHOR REBAR TYPICAL THRUST BLOCK BEDDING PER TYPICAL PER SCHEDULE TRENCH SECTION SW.5 WATER MAIN LOWERING SECTION DETAIL HOR NOTE: 1. COAT RODS WITH A BITUMASTIC NO. 50 COATING OR EQUAL, 2. PRESSURES SHOWN ARE MAXIMUM WORKING PRESSURES IN THE SYSTEM W 6 THRUST BLOCKING FOR WATER MAIN VALVES (MPWSS SO No. 02680-3) 212 WATER SYSTEM STANDARD DRAWINGS AND NOTES NOTES: 1. THESE TABLES ARE BASED ON 150 PSI MAIN PRESSURE & 200 PSF SOIL BEARING PRESSURE. 2. WRAP ALL FITTINGS WITH POLYETHYLENE. r STANDARD DIMENSIONS FOR THRUST BLOCKING FITTING TEES & PLUGS 90' BEND 45' BEND & WYES REDUCERS & 22' BEND SIZE A B A B A B A B 1'-fill 1'-8" o'-10" 1._7. O -fill 6" 2'-0" I 1'-11" 2'-5" 2'-2" l'-loll 1'-7" 1'-9" 0'-10" g^ 2'-8" I 2'-6" 3'-2" �3'-0" 2'-5" 2'-l" 11--9" 1'-8" 10" 3'-4" 3'-3" 4'-0" 3'-loll 3'-0" 2"-9" 2'-2" 1'-11" 12" 4'-0" 3'-10" 4'-8" 4'-8" 3'-8" 3'-3" 2'-7" 2'-3" 3'-5" 3'-5" 2'-5" %THRUST BLOCKING FOR WATER MAIN FITTINGS �1 (MPWSS SD No. 028O-1) L 2 i8" MIN} EXISTING PIPE CROSSING L� L 2 WATER] MAIN EXISTING NO VERTICAL PIPE REQUIREMENT 18" MIN© NEW PIPE SEWMAIN NOTE d SPECIFIC MONTANA DEPARTMENT OF HEALTH AND ENVIRONMENTAL SCIENCE APPROVAL IS REQUIRED FOR A DISTANCE LESS THAN 10 FEE( BETWEEN WATER AND SANITARY SEWER. !�2 NO EXCEPTION TO THE PIPE SEPARATION REQUIREMENT IS PERMITTED WHEN THE SEWAGE PIPE IS A FORCEMAIN. AT CROSSINGS, ONE FULL LENGTH OF WATER MAIN PIPE SHALL BE LOCATED SO THAT BOTH JOINTS WILL BE AS FAR FROM THE FORCEMAIN AS POSSIBLE. LESS THAN 18" OF SEPARATION IS PERMITTED WHEN THE GRAVITY SEWER AT THE CROSSING IS MADE FROM ONE SINGLE 20 FOOT LENGTH OF AWWA PRESSURE PIPE AND THE CROSSING ANGLE 1S APPROXIMATELY 90% SPECIFIC MONTANA DEPARTMENT OF HEALTH AND ENVIRONMENTAL SCIENCES APPROVAL IS REQUIRED FOR A VERTICAL SEPARATION OF LESS THAN 18" BETWEEN WATER MAIN AND SANITARY SEWER, "L" IS A LENGTH OF PIPE AS SUPPLIED BY THE MANUFACTURE. 5 ADEQUATE STRUCTURE SUPPORT FOR PIPES AT CROSSING SHALL BE PROVIDED. ow WATER MAIN AND SEWER MAIN SEPARATION (MPWSS SD No. 02660.2) 213 BUILDING 3' 1 3' ACCEPTABLE STANDARD WATER SYSTEM STANDARD DRAWINGS AND NOTES BUILDING 11 _w ! 1 1 UNACCEPTABLE STANDARD W.9 SERVICE LINE/FIRE SERVICE LINE DETAIL EX. WATER MAIN, SEE PLAN FOR SIZE AND MATERIAL 0 N UNDISTURBED TRENCH EXCAVATION ROMAC MODEL SST CONCRETE THRUST TAPPING SLEEVE, BLOCK SEE PLAN FOR SIZE MUELLER SERIES A-2360 RESILIENT WEDGE MJ x FL GATE VALVE. WITH STANDARD Sp. WRENCH NUT, ALL FLANGE BOLTS SHALL BE COR-BLUE OR COR-TEN, SEE PLAN FOR SIZE PIPE BEDDING TRENCH PER TYPICAL TRENCH SECTION DETAIL -CONCRETE SUPPORT BLOCK ol 0 - WATER MAIN TAPPING SADDLE 214 SANITARY SEWER STANDARD DRAWINGS AND NOTES SANITARY SEWER STANDARD DRAWINGS AND NOTES SANITARY SEWER SYSTEM CONSTRUCTION NOTES: 1. ROOF DRAINS, FOUNDATION DRAINS, STORM SEWERS, SUMP PUMPS AND OTHER CLEAN WATER CONNECTIONS TO THE SANITARY SEWER ARE STRICTLY PROHIBITED. 2. GRAVITY SANITARY SEWER SHALL BE SDR 35 PVC SEWER PIPE CONFORMING TO ASTM D-3034. PIPES SHALL BE CONSTRUCTED MEETING THE MINIMUM PIPE SLOPE REQUIREMENTS OF MONTANA DEQ CIRCULAR 2. 3. ALL PIPE SHALL BE CAPPED OR PLUGGED AT THE END OF EACH WORK DAY. 4. ALL MANHOLES AND FORCEMAIN VALVE BOXES SHALL HAVE A CONCRETE COLLAR PER CITY OF KALISPELL STANDARDS FOR DESIGN AND CONSTRUCTION. 5. SEWER FORCEMAINS SHALL BE INSTALLED WITH A 12 GAUGE SOLID CORE COPPER TONING WIRE WITH THERMOPLASTIC INSULATION RECOMMENDED FOR DIRECT BURY. THE TONER WIRE SHALL BE TAPED TO THE TOP OF THE SEWER FORCEMAIN AT INTERVALS OF NO MORE THAN 5 FT. TONER WIRE SHALL BE EXTENDED TO THE SURFACE AT ALL VALVE BOXES, LIFT STATIONS, AND AT MARKER POSTS. TONER WIRE SHALL BE ACCESSIBLE AT THE SURFACE WITH A MINIMUM 3 FEET OF EXCESS WIRE. 6_ ALL WATER AND SEWER CROSSINGS SHALL BE MADE AT PERPENDICULAR ALIGNMENTS. A MINIMUM OF 18 INCHES OF OUTSIDE PIPE WALL SEPARATION MUST BE MAINTAINED. A MINIMUM OF 10 FEET OF HORIZONTAL SEPARATION MUST ME BE MAINTAINED BETWEEN SANITARY SEWER AND POTABLE WATER MAINS. 7, THE TERMINAL END OF ALL SERVICE STUBS SHALL BE MARKED WITH METAL " T" POST AS INDICATED IN THE CITY OF KALISPELL STANDARDS FOR DESIGN OR CONSTRUCTION. B. ALL GRAVITY SANITARY SEWER MAIN SHALL BE LAID UPSTREAM WITH THE SPIGOT ENDS POINTING DOWNSTREAM. ALL PIPES SHALL BE SET AT CONSTANT GRADE AND ALIGNMENT BETWEEN MANHOLES. 9. SANITARY SEWER PIPE LINE AND APPURTENANCES SHALL BE CLEANED AND TESTED UPON COMPLETION OF BACKFILL OPERATIONS. ALL TESTING SHALL BE UNDER THE SUPERVISION OF THE PROJECT ENGINEER AND REPRESENTATIVE OF THE CITY OF KALISPELL PUBLIC WORKS DEPARTMENT. / 1 SEWER SYSTEM CONSTRUCTION NOTES f� �/SHELF CHANNEL SHELF "l f f \ l✓� \\ H CHANNEL NOTES: 1. SLOPE ALL SHELVES TO CHANNEL AT 1" PER FOOT 2. SEE PLAN -PROFILE SHEETS FOR SLOPE OF CHANNEL. TYPICAL MANHOLE CHANNEL DETAIL 215 SANITARY SEWER STANDARD DRAWINGS AND NOTES TYPICAL MANHOLE COLLAR PER CITY OF KALISPELL CONSTRUCTION STANDARDS MANHOLE RING AND RADIUS OF o MANHOLE SLOPE SHELF AT CASTING, SEE SA_8, OR w 1 INCH PER 1 FT APPROVED EQUAL oLa CHIMNEY SEAL � SECTION A -A 24.. ADJUSTING RINGS OPENING 2" MIN. - 12" MAX. ECCENTRIC CONE SECTION PRECAST CONCRETE X 4� MANHOLE MEETING ASTM C478 z z 00 EXTERIOR RUBBERIZED N JOINT SEALS CONCRETE ENCASEMENT, o Z 48" 3 Cf�FAR ui.----- �^ _. w ._. ./._._. N OrJ uj W W �! I 44 y SHELF -SLOPE 1" uF. lq� PER FOOT TOWARD CHANNEL, SEE CHANNEL DETAIL / • ` � Mqa j�, DROP INLET, USE a/ FOR DROP MANHOLE —A 1 CHANNEL 1 2 DIA. OF PIPE " FLEXIBLE GASKETED JOINT (TYP) DEFLECTION - Y A JOINT, TYPICAL PRE -CAST BASE SLAB, MINIMUM THICKNESS SHALL BE 6" BELOW BOTTOM OF PIPE MANHOLE NOTES: 1. ECCENTRIC MANHOLES REQUIRED ON ALL 4 FT DIAMETER MANHOLES GREATER THAN 5 FT IN OVERALL HEIGHT UNLESS SPECIFIED OTHERWISE. 2, ALL JOINTS BETWEEN MANHOLES SECTIONS, ADJUSTING RINGS, MANHOLE RING AND TOP SECTION, AND AROUND ALL SEWER PIPE IN MANHOLE SHALL BE WATER TIGHT. JOINTING MATERIAL SHALL BE "RAM-NEK" OR EQUAL FOR ALL JOINTS EXCEPT BETWEEN SEWER PIPE AND MANHOLE WALL. 3. FIELD SET COVER TO GRADE WHEN MANHOLE IS LOCATED WITHIN A STREET OR ALLEY. 4. SHELVES SHALL SLOPE AT 1" PER FOOT TOWARD CHANNEL. SANITARY SEWER MANHOLE DETAIL 216 45' ELBOW SANITARY SEWER MAIN SANITARY SEWER STANDARD DRAWINGS AND NOTES 5' METAL "T" POST,- MIN- 3' BURIED AND 2' ABOVE GROUND, PAINT GREEN EXTEND BEYOND — PROPERTY LINE AND UTILITY EASEMENT Y, _ 1w COMPACTED BACKFILL WOOD 2" x 4" PVC BELL AND SPIGOT PIPE, MIN. 4", MIN SLOPE 1J4" PER 12" � SERVICE LINE PLUG IN LINE WYE FOR NEW INSTALLATIONS, SADDLE AS APPROVED BY ENGINEER FOR EXISTING INSTALLATIONS NOTES: 1. NO SERVICE CONNECTIONS SHALL BE MADE AT MANHOLES, EA N 0 E o R E BEFORE DIGGING IN THIS AREA CALL TYPICAL SANITARY SEWER SERVICE TRIVIEW 3 FACE FLEXIBLE MARKER POST GREEN 1N COLOR, MARKED SEWER 36" MAX TYPICAL MANHOLE COLLAR PER CITY OF KALISPELL CONSTRUCTION STANDARDS NOTES: 1. SEWER TRIVIEW MARKER POSTS SHALL BE INSTALLED FOR ALL MANHOLES LOCATED OUTSIDE OF PAVED OR GRAVEL AREAS. TYPICAL SEWER MANHOLE MARKER POST 217 SANITARY SEWER STANDARD DRAWINGS AND NOTES TYPICAL MANHOLE COLLAR PER CITY OF KALISPELL CONSTRUCTION STANDARDS DETECTABLE WARNING TAPE, MIN. 3" IN WIDTH, APWA COLORS 5' MAX COIL TONING WIRE TO INTERIOR OF VALVE BOX CAST IRON, 3 PIECE SLIP VALVE BOX, TYLER 6865 SERIES, OR APPROVED EQUAL MARKED SEWER FLANGED, RESILIENT SEAT, ECCENTRIC PLUG VALVE, WITH STANDARD SO. WRENCH NUT, SEE PLAN FOR SIZE SANITARY SEWER FORCEMAIN,--J NOTES: 1. VALVES 6" AND LARGER SHALL HAVE WORM GEAR REDUCTION ACTUATOR WITH 2" SQUARE NUT. 2. VALVES INSTALLED WITH WORM GEAR SHALL FLOW ENTERING SEAT END OF VALVE AND THE PLUG BEING UP IN OPEN POSITION. SA.6 TYICAL FORCEMAIN VALVE SECTION DETAIL COAT ALL INTERIOR SURFACES OF CONCRETE MANHOLE WITH 100% SOLIDS HIGH BUILD CHEMICAL RESISTANT EPDXY TO RESIST HYDROGEN SULFIDE ATTACK EXTERIOR RUBBERIZED JOINT SEALS STAINLESS STEEL PIPE ANCHOR, DRILL INTO CONCRETE AND EPDXY 45' BEND WITH PLAIN END, ROTATE IN DIRECTION OF FLOWLINE CHIMNEY SEAL AIR VENT RISER FLEXIBLE JOINT BOOT I I -CONCRETE RETRAINING COLLAR FOR HDPE FORCEMAINS FO-'-ICI-RCEMAIN I r- -- - I I I DR 11 HDPE PIPE, i OR COATED 01 PIPE IBLE JOINT BOOT CONCRETE JJ COLLAR H PiEING FORCEMAIN FORM SMOOTH CONCRETE CHANNEL TO MANHOLE OUTFALL .FORCE rTtAJAAXSCAARGE4TlAA AOLE DETAIL 218 SANITARY SEWER STANDARD DRAWINGS AND NOTES 1" LETTERING (RECESSED FLUSH) 9ti',�� (2) PICKHOLES (SEE DETAIL) 1" LEITERING (RECESSED RUSH) 25 3/4"--� 1" 4" COVER SECTION ih 3771A1 irco rrr s 2 3/4" 1 1/2" PICKHOLE DETAIL SANITARY MANHOLE COVER 219 STORM SEWER STANDARD DRAWINGS AND NOTES STORM SEWER STANDARD DRAWINGS AND NOTES 6" CONCRETE APRON, PER CITY OF KALISPELL STANDARDS FOR DESIGN AND CONSTRUCTION EDGE OF CONCRETE 12- 3J8" BELOW PAVEMENT CONCRETE ADJUSTMENT RING,- 2" MIN, 12' MAX CONCRETE CATCH BASIN ZORM PIPE, SEE N FOR SIZE AND SLOPE FLEXIBLE GASKETED OR BOOTED JOINT. GROUT INTERIOR 5" OF 3" MINUS CRUSHED COMPACTED AGGREGATE FOUNDATION EAST JORDAN IRON WORKS #7222, OR OLYMPIC FOUNDRY SM498 STORM INLET FOR STAND UP CURB AND GUTTER EAST JORDAN IRON WORKS #7711, OR OLYMPIC FOUNDRY SM44, STORM INLET FOR DRIVE OVER CURB AND GUTTER NOTE: 1. ALL JOINTS BETWEEN CATCH BASIN, ADJUSTMENT RINGS, CASTING, AND SEWER PIPE SHALL BE WATER TIGHT. JOINING MATERIAL SHALL BE RAM-NEK OR EQUAL FOR ALL JOINTS OTHER THAN JOINTS BETWEEN SEWER PIPE AND CATCH BASIN. 2. ALL PIPE CONNECTIONS NOT CONSTRUCTIBLE AS DETAILED SHALL BE SUBMITTED TO CITY ENGINEER FOR REVIEW. ODRITYPICAL STORMWATER CATCH BASIN DETAIL CONCRETE CATCH BASIN 6' OF 3" MINUS CRUSHED COMPACTED AGGREGATE FOUNDATION EAST JORDAN IRON WORKS, 5031M FRAME AND 5031Z GRATE CONCRETE ADJUSTMENT RING, 2" MIN, 12' MAX NI I STORM PIPE, SLOPE PER PLAN j I FLEXIBLE OR BOOTED JOINT, GROUT INTERIOR NOTE; 1. ALL JOINTS BETWEEN CATCH BASIN, ADJUSTMENT RINGS, CASTING, AND SEWER PIPE SHALL BE WATER TIGHT. JOINING MATERIAL SHALL BE RAM-NEK OR EQUAL FOR ALL JOINTS OTHER THAN JOINTS BETWEEN SEWER PIPE AND CATCH BASIN. 2. ALL PIPE CONNECTIONS NOT CONSTRUCTIBLE AS DETAILED SHALL BE SUBMITTED TO CITY ENGINEER FOR REVIEW. F-2 GUTTER CATCH BASIN INLET PLAN DETAIL 220 CONCRETE MANHOLE COLLAR, PER CITY OF KALISPELL STANDARDS FOR DESIGN AND CONSTRUCTION EDGE OF CONCRETE 3/8" BELOW PAVEMENT z CONCRETE ADJUSTMENT RING, N 2' MIN, 12' MAX STORM PIPE, SEE PLAN FOR SIZE AND SLOPE FLEXIBLE GASKETED OR BOOTED JOINT, GROUT INTERIOR STORM SEWER STANDARD DRAWINGS AND NOTES a STORM MANHOLE RING AND COVER, SEE DR,B, OR APPROVED EQUAL PRECAST CONCRETE MANHOLE MEETING ASTM C478 NOTE: 1. ALL JOINTS BETWEEN MANHOLE, ADJUSTMENT RINGS, CASTING, AND SEWER PIPE SHALL BE WATER TIGHT. JOINING MATERIAL SHALL BE RAM-NEK OR EQUAL FOR ALL JOINTS OTHER THAN JOINTS BETWEEN SEWER PIPE AND CATCH BASIN. 2. ALL PIPE CONNECTIONS NOT CONSTRUCTIBLE AS DETAILED SHALL BE SUBMITTED TO CITY ENGINEER FOR REVIEW. DR 3 TYPICAL STORMWATER MANHOLE DETAIL EROSION AND SEDIMENT CONTROL NOTES: 1. THE CONTRACTOR SHALL BE RESPONSIBLE TO OBTAIN ALL PERMITS ASSOCIATED WITH THIS PROJECT AND IMPLEMENT AND MAINTAIN THE EROSION AND SEDIMENT CONTROL PLAN AND PERMITS REQUIREMENTS UNTIL SUCH TIME AS THE PERMITS ARE TERMINATED. 2- THE CONTRACTOR 1S RESPONSIBLE TO MAINTAIN OR CHANGE THE EROSION AND SEDIMENT CONTROL PLAN AS THE PROJECT PROGRESSES TO ENSURE PERMIT COMPLIANCE. 3. THE CONTRACTOR SHALL REMOVE ALL SEDIMENT, MUD, AND CONSTRUCTION DEBRIS THAT MAY ACCUMULATE IN THE PUBLIC RIGHT OF WAY AS A RESULT OF THIS PROJECT. SAID MATERIAL SHALL BE REMOVED DAILY OR MORE FREQUENTLY PER THE CITY'S REQUEST. 4. THE CONTRACTOR SHALL ENSURE ALL CUT AND FILL MATERIAL IMPORTED TO OR EXPORTED FROM THIS SITE IS PROPERLY COVERED TO PREVENT LOSS OF THE MATERIAL DURING TRANSPORT ON PUBLIC RIGHTS OF WAY. 5. THE CONTRACTOR SHALL ENSURE ALL CUT AND FILL MATERIAL IMPORTED OR EXPORTED iS NOT STORED IN THE PUBLIC RIGHT OF WAY. 6. ALL STOCKPILED MATERIAL SHALL BE DESIGNATED ON THE EROSION AND SEDIMENT CONTROL PLAN, 7. TEMPORARY BMPS ON THE EROSION PLAN SHALL BE INSTALLED PRIOR TO ANY EXCAVATION. 8. INLET PROTECTION BMPS SHALL BE INSTALLED PRIOR TO ANY EXCAVATION AND MAINTAINED UNTIL PAVING IS COMPLETE, INLET PROTECTION BMPS SHALL BE APPROVED BY THE CITY OF KALISPELL PRIOR TO INSTALLATION. EROSIaN AND SEDIMENT CONTROL NOTES VR.Y 221 /y Sf �• j54 SILT FENCE-' STORM SEWER STANDARD DRAWINGS AND NOTES MIN. LENGTH MIN, WIDTH bEMMERCIAL SIDENTIAL 30 FT 15 FT 60 FT 25 FT % FILTER FABRIC-/ -VEHICLE TRACKING PAD 14" OF 3" -6" STONE NOTE: ALL VEHICLES ENTERING AND EXITING THE CONSTRUCTION AND/OR BUILDING SITE SHALL TRAVERSE THE VEHICLE TRACKING PAD TO MINIMIZE MUD AND DIRT FROM TRACKING OFF SITE. ROCK SHALL BE REPLENISHED IF TRACKING OCCURS. TRACKING PAD SHALL BE RENEWED AS NECESSARY TO RETAIN EFFECTIVENESS. ALL MATERIALS SPILLED, DROPPED, WASHED OR TRACKED FROM VEHICLES ONTO ROADWAYS SHALL BE REMOVED IMMEDIATELY. VFH€CIF TRACKING STONE ENTRANCE R QUIR M NTS: • 3"-6" DIAMETER WASHED ROCK • UNDERLYING FILTER FABRIC TO BE REQUIRED AS STATED FILTER FABRIC REQUIREMENTS. • TENSILE GRAB STRENGTH = 200 LBS (ASTM D4632) • ELONGATION MINIMUM = 15% (ASTM D4632) • SEAM BREAKING STRENGTH MINIMUM = 180 LBS (ASTM D4632) • APPARENT OPENING SIZE MAXIMUM = 0.3 MM (#50 SIEVE) (ASTM D4751) • PERMITIVITY MINIMUM = 0.3/SEC (ASTM 04491) DR.5 VEHICLE TRACKING STORMWATER BMP 36" MIN WOOD, OR STEEL POST GEOTEXTILE FABRIC ILTER ( �FABRIC INTO GROUN NUIt: 1. SILT FENCE SHALL BE USED AS A TEMPORARY SEDIMENT CONTROL, FENCES SHALL BE INSTALLED WITH THE CONTOUR OF SLOPE. 2. WOOD POSTS SHALL BE HARDWOOD WITH AND MINIMUM CROSS SECTION AREA OF THREE INCHES. 3. TEMPORARY SILT FENCE SHALL BE REMOVED UPON SITE STABILIZATION WITH 70% ESTABLISHED VEGETATIVE COVER. GEOTFXTILE FABRIC REQUIREMENTS: • TENSILE GRAB STRENGTH = 90 LBS (ASTM 01682) • ELONGATION MINIMUM = 50% (ASTM D1682) • MULLEN BURST STRENGTH MINIMUM = 190 LBS (ASTM D3786) • PUNCTURE STRENGTH MINIMUM = 40 LBS (ASTM D751) • EQUIVALENT OPENING SIZE MAXIMUM = 40-80 US STANDARD SIEVE SIZES • ULTRAVIOLET RADIATION STABILITY = 90 (ASTM G26) / _ - SILT FENCE STORMWATER BMP 222 STORM SEWER STANDARD DRAWINGS AND NOTES ,RT EROSION CONTROL BLANKET 4TERED ON CHANNEL AT OUTLET. BLANKET PARALLEL TO CENTER CHANNEL, OVER LAP ALL SEAMS ) JOINTS 12 INCHES MINIMUM. EROSION CONTROL BLANKET FOR SLOPE PROTECTION NOTES: 1. PREPARE SOIL BEFORE INSTALLING BLANKETS, INCLUDING APPLICATION OF FERTILIZER AND SEED. 2. BEGIN AT TOP OF SLOPE BY ANCHORING THE BLANKET IN A 6' DEEP x 6' WIDE TRENCH. BACKFILL AND COMPACT THE TRENCH AFTER STAPLING. 3. ROLL BLANKETS DOWN, STARTING AT DOWNSTREAM PROCEEDING UPSTREAM, HORIZONTALLY ACROSS THE SLOPE. 4. PARALLEL BLANKETS MUST BE STAPLED WITH A 4' OVERLAP. 5. SPLICE BLANKETS ONLY AS NECESSARY, PLACE BLANKETS END OVER END WITH AN 12" OVERLAP. USE DOUBLE ROW OF STAGGERED STAPLES 4" APART TO SECURE BLANKET, 6. IN HIGH FLOW APPLICATIONS STAPLE WITH DOUBLE STAGGERED ROW EVERY 30' TO 40'. USE A ROW OF STAPLES 4" A PART OVER ENTIRE WIDTH OF CHANNEL, USE SECOND ROW 4" BELOW THE FIRST ROW IN A STAGGERED PATTERN. 7. THE TERMINAL END OF THE BLANKETS SHALL BE ANCHORED IN A 6" x 6" TRENCH. BACKFILL AND COMPACT AFTER STAPLING. DR 7 EROSION CONTROL BLANKET BMP 1" LETTERING (RECESSED FLUSH) 1" of Ko;t 1 1/2„ 3771A1 � ,ue cues ireo ns �4A4 Sy- (2) PICKHOLES (SEE DETAIL) 1" LETTERING (RECESSED FLUSH) 25 3/4"� 1 4" COVER SECTION COVER SACK 2 3/4' 1 1/2" 1" 1 1/2" 7/8' PICKHOLE DETAIL STORM MANHOLE COVER un.a 223 STREET STANDARD DRAWINGS AND NOTES STREET STANDARD DRAWINGS AND NOTES 60' RIGHT OF WAY 10' 5' 6' i' 17' _ 17' _ 6' S10' M f� x EASEMENT -•-W- � t ' ADA SIDEWALK SI EWPLK ! RAMP, TYP. �PAVEMENT MARKING i AS REQUIRED, 8" WHIT�CROSSWA SS PAVEMENT MARK AS REQUIRED, 24" WHITE STOP 1 R I 1 STREET AND STOP SIGN, TYP, I m w BASIN, M Ell In 60' RIGHT OF WAY SIDEWALK CURB AND GUTTER BOULEVARD 17' 17' 6' S' ` �-g;t"ASPHALT CRUSHED BASE 15" SELECT SUB -BASE 40' d SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS ALL NEW UTILITIES SHALL BE PLACED UNDERGROUND. EXCEPT FOR SEWER AND WATER, UNDERGROUND UTILITIES, IF PLACED IN RIGHT OF WAY OR EASEMENT SHALL BE LOCATED BETWEEN THE BACK OF SIDEWALK AND EASEMENT LINE. NO UNDERGROUND UTILITIES SHALL BE PLACED IN THE BOULEVARD BETWEEN THE BACK OF CURB AND SIDEWALK. ST COLLECTOR STREET J1.1 224 In STREET STANDARD DRAWINGS AND NOTES 60' RIGHT OF WAY 10' 5' T 9' F 14' 14' 4' +5' 10' € f � ( I EASEMENT ? SIDEWALK EASEMENT ADA SIDEWALK RAMP, ITYP STREET AND STOP SIGN, TYP. ------------- w ___ ____ ____ w --- ..--- --- .--- .._ j._.--- ..--- ._- SIDEWALK CURB AND GUTTER BOULEVARD 14' � _ 14' 9' S• F 4" ASPHALT ,. 6" CRUSHED BASE 9" SELECT SUB -BASE 34' 0 SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS Im ALL NEW UTILITIES SHALL BE PLACED UNDERGROUND. EXCEPT FOR SEWER AND WATER, UNDERGROUND UTILITIES, IF PLACED IN RIGHT OF WAY OR EASEMENT SHALL BE LOCATED BETWEEN THE BACK OF SIDEWALK AND EASEMENT LINE. NO UNDERGROUND UTILITIES SHALL BE PLACED IN THE BOULEVARD BETWEEN THE BACK OF CURB AND SIDEWALK. LOCAL STREET JI.L 225 STREET STANDARD DRAWINGS AND NOTES 10' EASEMENT ,' `I_ 16 � 12' 12 �'T' 4' . 6' STREET AND STOP SIGN, TYP, 1 60' 28, 12' 1 I . 10' EASEMENT 2'l` 1 2 12 12 Z..._, 2% r- I 2% 10' CLEAR r - - i 6 CRUSHED BASE * " 9" SELECT SUB -BASE 8 CRUSHED BASE SHOULDER *U SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS UTILITY NOTE: ALL NEW UTILITIES SHALL BE PLACED UNDERGROUND. EXCEPT FOR SEWER AND WATER, UNDERGROUND UTILITIES, IF PLACED IN RIGHT OF WAY OR EASEMENT SHALL BE LOCATED OUTSIDE OF DITCH SECTIONS, AND BIKE PATHS. NO PRIVATE UNDERGROUND UTILITIES SHALL BE PLACED IN THE PUBLIC RIGHT-OF-WAY. 1. THIS CROSS SECTION MAY BE USED ONLY WHEN THE AREA ADJACENT TO THE PROPOSED DEVELOPMENT DOES NOT HAVE CURBING OR ESTABLISHED STORM DRAINAGE SYSTEMS. THIS CROSS SECTION SHALL ONLY BE USED IN Ri ZONING AND MUST BE APPROVED BY THE CITY COUNCIL PRIOR TO INCORPORATING INTO THE DRAWINGS. 2. A 10 FT CLEAR ZONE MUST BE MAINTAINED ADJACENT TO SHOULDER OF ROAD. NO ADDRESS POSTS OR MAILBOXES MAY BE PLACED IN THE CLEAR ZONE. RURAL STREET 226 STREET STANDARD DRAWINGS AND NOTES 20' RIGHT OF WAY 1' 6' s 2x 2� $�i 1-12 4 ASPHALT" CRUSHED BASE SELECT SUB -BASE (* SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS RESIDENTIAL 20' RIGHT OF WAY 2% \�j 4 ASPHALT 6" CRUSHED BASE 15" SELECT SUB -BASE O SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS COMMERCIAL ST A ALLEY TYPICAL SECTION d ASPHALT - SHALL BE TYPE B (ASPHALT CONCRETE PAVEMENT SURFACE COURSE TYPE B SHALL BE ACCOMPLISHED IN ACCORDANCE WITH SECTION 02510 MONTANA PUBLIC WORKS STANDARD SPECIFICATIONS, FIFTH EDITION, APRIL 2010. SEE CITY OF KALISPELL STANDARDS FOR DESIGN AND CONSTRUCTION FOR PAVEMENT AND MATERIAL TESTING REOUIREMENTS. ® CRUSHED GRAVEL BASE, -3/4" DIAMETER 095% MAX DRY DENSITY (t 3% OPTIMUM MOISTURE) PER AASHTO T-99 0 SELECT SUB -BASE 095% MAX DRY DENSITY (+ 37. OPTIMUM MOISTURE) PER AASHTO T-991. i D CRUSHED GRAVEL SHOULDER, -3/4" DIAMETER 0 95% MAX DRY DENSITY (+/- 37. OPTIMUM MOISTURE) PER AASHTO T-99. A. THICKNESSES OF ASPHALT, CRUSHED GRAVEL AND SUB -BASE SHALL BE AS SHOWN, UNLESS AN ALTERNATE DESIGN IS APPROVED. THE FINAL STREET DESIGN SHALL BE APPROVED BY THE CITY ENGINEER PRIOR TO START OF CONSTRUCTION. B. THE WIDTH OF THE RIGHT-OF-WAY MAY BE INCREASED DUE TO UTILITIES. OR OTHER REQUIREMENTS. C. THE MAXIMUM GRADE SHALL BE 8%. D. ON STREET PARKING GOVERNED BY CITY OF KALISPELL SUBDIVISION REGULATIONS. ROAD CONSTRUCTION NOTES AND SPECIFICATIONS 227 STREET STANDARD DRAWINGS AND NOTES 1. 1/2" EXPANSION JOINT MATERIAL SHALL BE PLACED AT EACH POINT OF CURVATURE AND POINT OF TANGENCY. 2. CONTRACTION JOINTS SHALL BE PLACED AT EVERY 10' OF CURB LENGTH AND SHALL HAVE A MINIMUM DEPTH OF 0j- AND A MINIMUM WIDTH OF 1/8", CONTRACTION JOINTS SHALL BE CONSTRUCTED BY SAWING OR SCORING. A TOOL SHALL BE USED WHICH WILL LEAVE CORNERS ROUNDED AND DESTROY AGGREGATE INTERLOCK FOR THE SPECIFIED MINIMUM DEPTH. 3. EXPOSED EDGES SHALL HE FINISHED TO A RADIUS OF 1/4". _ 4_ CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM AGGREGATE, MINIMUM 28—DAY STRENGTH OF 4000 PSI, 6%-± 1 1/2% AIR ENTRAINMENT, AND MAXIMUM SLUMP OF 4". 5. INDIVIDUAL CONTRACTORS FORMS MAY VARY SLIGHTLY FROM THIS PATTERN. PATTERNS DIFFERING MATERIALLY FROM THE ABOVE DIMENSIONS SHALL BE SUBMITTED TO THE CITY FOR REVIEW. 6. FOUR INCHES OF CRUSHED GRAVEL BASE MATERIAL, —3/4" DIAMETER IS REQUIRED FOR THE CURB AND GUTTER FOUNDATION, THE BASE MATERIAL SHALL BE COMPACTED TO 95% DENSITY (± 3% OPTIMUM MOISTURE) PER AASHTO T-99. a� STANDARD CURB AND GUTTER SECTION 1, 1/2" EXPANSION JOINT MATERIAL SHALL BE PLACED AT EACH POINT OF CURVATURE AND POINT OF TANGENCY. 2. CONTRACTION JOINTS SHALL BE PLACED AT EVERY 10' OF CURB LENGTH AND SHALL HAVE A MINIMUM DEPTH OF Ur„ AND A y MINIMUM WIDTH OF 1/8". CONTRACTION JOINTS SHALL BE 1 f CONSTRUCTED BY SAWING OF SCORING. A TOOL SHALL BE USED tt WHICH WILL LEAVE CORNERS ROUNDED AND DESTROY AGGREGATE INTERLOCK FOR THE SPECIFIED MINIMUM DEPTH. 3. EXPOSED EDGES SHALL BE FINISHED TO A RADIUS OF 1/4". c+� 4. CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM ,. AGGREGATE. MINIMUM 28—DAY STRENGTH OF 4000 PSI. 6%f 1 1/2% AIR ENTRAINMENT, AND MAXIMUM SLUMP OF 4'. ' w 5. INDIVIDUAL CONTRACTORS FORMS MAY VARY SLIGHTLY FROM THIS PATTERN, PATTERNS DIFFERING MATERIALLY FROM THE ABOVE DIMENSIONS SHALL BE SUBMITTED TO THE CITY FOR 2' REVIEW. 6. FOUR INCHES OF CRUSHED GRAVEL BASE MATERIAL, —3/4- DIAMETER IS REQUIRED FOR THE CURB AND GUTTER FOUNDATION. THE BASE MATERIAL SHALL BE COMPACTED TO 95% DENSITY (+ 3% OPTIMUM MOISTURE) PER AASHTO T-99. 7, THIS CURB DOES NOT MEET HANDICAPPED ACCESS REQUIREMENTS AND SHALL NOT BE USED FOR ACCESS RAMPS. STANDARD DRIVE OVER CURB AND GUTER 228 8 STREET STANDARD DRAWINGS AND NOTES 1. 1/2" EXPANSION JOINT MATERIAL SHALL BE PLACED AT EACH POINT OF CURVATURE AND POINT OF TANGENCY. 2. CONTRACTION JOINTS SHALL BE PLACED AT EVERY 10' OF CURB LENGTH AND SHALL HAVE A MINIMUM DEPTH OF %" AND A MINIMUM WIDTH OF 1/8'. CONTRACTION JOINTS SHALL BE CONSTRUCTED BY SAWING OR SCORING. A TOOL SHALL BE USED WHICH WILL LEAVE CORNERS ROUNDED AND DESTROY AGGREGATE INTERLOCK FOR THE SPECIFIED MINIMUM DEPTH. 3. VISIBLE EDGES SHALL BE FINISHED TO A RADIUS OF 1/4", UNLESS OTHERWISE NOTED. 4. GRADE, ALIGNMENT AND FORMS SHALL BE INSPECTED BY THE CITY PRIOR TO POURING. 5. CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM AGGREGATE, MINIMUM 28-DAY STRENGTH OF 4000 PSI, 6% TO 8% AIR ENTRAINMENT, AND MAXIMUM SLUMP OF 4"- 6. INDIVIDUAL CONTRACTORS FORMS MAY VARY SLIGHTLY FROM THIS PATTERN, PATTERNS DIFFERING MATERIALLY FROM THE ABOVE DIMENSIONS SHALL BE SUBMITTED TO THE CITY FOR REVIEW. 7. FOUR INCHES OF CRUSHED GRAVEL BASE MATERIAL, -3/4" DIAMETER IS REQUIRED FOR THE CURB FOUNDATION. THE BASE MATERIAL SHALL BE COMPACTED TO 95% MOD (+/- 3% MOISTURE) PER AASHTO T-99. B. IF SLIP -FORMS ARE USED, A TEST SECTION SHALL BE POURED. INSPECTED AND APPROVED BY THE PUBLIC WORKS DEPARTMENT PRIOR TO PLACEMENT OF ANY PERMANENT STRAIGHT CURB. 9. ONLY ALLOWED WITH SPECIFIC APPROVAL OF CITY ENGINEER TO MATCH EXISTING CURB. STRAIGHT CURB SECTION 5' 9' LOCAL ST. 6' COLLECTOF S=2.00% MAXI{ S=2.007. MIN BOULEVARD 1. PRE -FORMED 1/2" EXPANSION JOINT MATERIAL MEETING THE REQUIREMENTS OF AASHTO M-213 SHALL BE PLACED AT 45-FOOT INTERVALS AND AT ALL COLD JOINTS. 2. CONTRACTION JOINTS SHALL BE SPACED THE APPROXIMATE SAME DIMENSION AS THE WIDTH, BUT NOT TO EXCEED SIX FEEF. CONTRACTION JOINTS SHALL BE CONSTRUCTED BY SAWING OR SCORING. A TOOL SHALL BE USED WHICH WILL LEAVE THE EDGES ROUNDED AND DESTROY AGGREGATE INTERLOCK FOR THE SPECIFIED MINIMUM DEPTH. CONTRACTION JOINTS SHALL BE A MINIMUM OF Y, TIMES THE SIDEWALK THICKNESS. 3. ALL VISIBLE EDGES AND JOINTS SHALL BE ROUNDED WITH AN EDGING TOOL WITH A MINIMUM 1/4" RADIUS. 4. CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM AGGREGATE. MINIMUM 28-DAY STRENGTH OF 4000 PSI, 8%f 1 1/2% AIR ENTRAINMENT, AND MAXIMUM SLUMP OF 4". 5. SIX INCHES OF CRUSHED GRAVEL WE MATERIAL, -3/4" DIAMETER IS REQUIRED FOR THE SIDEWALK FOUNDATION. THE BASE MATERIAL SHALL BE COMPACTED TO 95% DENSITY (± 3% OPTIMUM MOISTURE) PER AASHTO T-99. 6. SIDEWALK MINIMUM THICKNESS: RESIDENTIAL: 4° COMMERCIAL OR AT DRIVE APPROACH: 6" STANDARD SIDEWALK SECTION 229 STREET STANDARD DRAWINGS AND NOTES —A 1. BASE MATERIAL SHALL BE CRUSHED GRAVEL, —3/4" DIAMETER COMPACTED SIDEWALK TO 95% DENSITY (+/— 3% OPTIMUM MOISTURE) PER AASHTO T-99. .. FLOWLINE 2. CONCRETE SHALL BE M-4000 WITH BOULEVARD DV CON CRETL CURB AND GUTTER 3/4- MAXIMUM AGGREGATE, MINIMUM tO 28—DAY STRENGTH OF 4000 PSI, 6% 1 1/2% AIR ENTRANEMENT, AND MAXIMUM SLUMP OF 4" 4' EXPANSION JOINT TRANSITION TRANSITION SIDEWALK APRON W/6- BASE MATERIAL 5. 6, 6' CONCRETE ST.10 DRIVEWAY DETAIL FOR CURB & GUTTER _ A 1. BASE MATERIAL SHALL BE CRUSHED GRAVEL, — 3/4" DIAMETER Lo SIDEWALK COMPACTED TO 95% MAX DRY DENSITY (+/— 3% OPTIMUM MOISTURE) PER AASHTO T-99. c 6�TE NCR BOULEVARD 2. CONCRETE SHALL BE M-4000 WITH io 3/4- MAXIMUM AGGREGATE, MINIMUM 28 DAY STRENGTH OF 4000 PSI, 6% +/— 1.5% AIR ENTRAINMENT, AND A MAXIMUM SLUMP OF 4" TRANSITION —A TRANSITION SIDEWALK APRON"CONCRETE 51 6' MIN -.A I VERTICAL EXPOSURE ACROSS 2% MAX I DRIVEWAY SECTION SECTION A -A BASE MATERIAL e- DRIVEWAY DETAIL FOR STRAIGHT CURB 230 24" MINIMUM BACK OF CURB TO EDGE OF SIGN 'STOP' SIGN SIZED PER MUTCD (MIN. 30"J 2" RIGID GALVANIZED PIPE 10' LONG 2" ID 2 3/8" OD 2" GALVANIZED COUPLING FLUSH WITH TOP OF CONCRETE BASE 1/2" x 4" HEX BOLT ANCHOR 18" DIA. X 24" DEEP 3000 PSI CONCRETE BASE STREET STANDARD DRAWINGS AND NOTES ALL SIGN BLANKS SHALL BE 0.080 GAUGE FIAT ALUMINUM STOCK. STREET NAME SIGN BLANKS SHALL BE 9" IN HEIGHT. LENGTH SHALL BE DETERMINED BY THE STREET NAME. STOP SIGN FACES SHALL BE 3M HIGH INTENSITY GRADE REFLECTIVE SHEETING OR APPROVED EQUAL. STREET SIGN SHALL BE WHITE ON GREEN PRISMATIC SHEETING, MINIMUM LEVEL IV, ACCORDING TO MUTCD. LETTERING SHALL BE 6" HIGH IN CAPITAL LETTERS. 4.5" LOWER CASE LETTERS, FOR >40 MPH. STOP SIGNS SHALL BE ATTACHED TO THE SIGN POST WITH A U-BOLT STYLE SIGN MOUNTING CLAMP. STREET NAME SIGNS SHALL BE ATTACHED TO THE TOP OF THE SIGN POST WITH A ROUND CAP SIGN HOLDER WITH A 12" LONG MOUNTING BRACKET. A 12" LONG 9V CROSSPIECE SHALL BE USED FOR DUAL SIGN APPLICATIONS. 12 12 STANDARD STREET SIGN DETAIL 4000 PSI CONCRETE 4' N C- SECTION A -A REINFORCED WITH 10/10 6x6 WWF SUPPORTED WITH #3 REINFORCING BARS AT 48" ON CENTER EACH WAY ON 3" CHAIRS CST - INTERSECTION GUTTER DETAIL ST-13 231 STREET STANDARD DRAWINGS AND NOTES NG NS, INC OR . �D IN COLOR 1. PEDESTRIAN RAMPS SHALL COMPLY WITH THE AMERICANS WITH DISABILITIES ACT/ACCESSIBILITY GUIDELINES FOR BUILDINGS AND FACILITIES. 2. THE LEAST POSSIBLE SLOPE SHALL BE USED FOR PEDESTRIAN RAMPS. THE MAXIMUM SLOPE SHALL BE 1:12 (8.33%). 3. THE CROSS SLOPE SHALL BE NO GREATER THAN 1:48 (2%). 4. A LANDING AREA THE WIDTH OF THE RAMP AND AT LEAST 36 INCHES IN LENGTH SHALL BE PROVIDED AT THE TOP OF THE RAMP. SLOPE OF THE LANDING SHALL NOT EXCEED 1:48 (2%) IN ALL DIRECTIONS. 5. ALTERNATE DESIGNS AND LOCATIONS SHALL MEET THE REQUIREMENTS OF THE AMERICANS WITH DISABIUTES ACT/ACCESSIBILITY GUIDELINES FOR BUILDINGS AND FACILITIES AND SHALL BE APPROVED BY THE PUBLIC WORKS DEPARTMENT PRIOR TO START OF CONSTRUCTION. 6. PEDESTRIAN RAMPS SHALL BE A MINIMUM OF 60 INCHES WIDE. � TYPICAL PEDESTRIAN RAMP DETAIL 2' WING AND CURB TRANSITION 24" x 60" CAST IN PLACE REPLACEABLE TACTILE WARNING SURFACE TILE. ADA SOLUTIONS, INC OR APPROVED EQUAL, BRICK RED IN COLOR 1. PEDESTRIAN RAMPS SHALL COMPLY WITH THE AMERICANS WITH DISABILITIES ACT/ACCESSIBILITY GUIDELINES FOR BUILDINGS AND FACILITIES. 2. THE LEAST POSSIBLE SLOPE SHALL BE USED FOR PEDESTRIAN RAMPS. THE MAXIMUM SLOPE SHALL BE 1A 2 (8.33%). 3. THE CROSS SLOPE SHALL BE NO GREATER THAN 1:48 (2%). 4. A LANDING AREA THE WIDTH OF THE RAMP AND AT LEAST 36 INCHES IN LENGTH SHALL BE PROVIDED AT THE TOP OF THE RAMP. SLOPE OF THE LANDING SHALL NOT EXCEED 1:48 (2%) IN ALL DIRECTIONS. 5. ALTERNATE DESIGNS AND LOCATIONS SHALL MEET THE REQUIREMENTS OF THE AMERICANS WITH DISABILITES ACT/ACCESSIBILITY GUIDEUNES FOR BUILDINGS AND FACILITIES AND SHALL BE APPROVED BY THE PUBLIC WORKS DEPARTMENT PRIOR TO START OF CONSTRUCTION. 6. PEDESTRIAN RAMPS SHALL BE A MINIMUM OF 60 INCHES WIDE. 232 STREET STANDARD DRAWINGS AND NOTES I MAXIMUM O uvc 1:12 ,-•SIDEWA[tfA' 60" x 24" CAST IN PLACE MAX REPLACEABLE TACTILE WARNING SURFACE TILE, ADA SOLUTIONS, INC. OR APPROVED 27. EQUAL BRICK RED IN COLOR _p .Sy 6AY RETROFIT AREA 1. PEDESTRIAN RAMPS SHALL COMPLY WITH THE AMERICANS WITH DISABILITIES ACT/ACCESSIBILITY GUIDELINES FOR BUILDINGS AND FACILITIES. 2. THE LEAST POSSIBLE SLOPE SHALL BE USED FOR PEDESTRIAN RAMPS, THE MAXIMUM SLOPE SHALL BE 1:12 (8.33%). 3. THE CROSS SLOPE SHALL BE NO GREATER THAN 1:48 (2R). 4. A LANDING AREA THE WIDTH OF THE RAMP AND AT LEAST 36 INCHES IN LENGTH SHALL BE PROVIDED AT THE TOP OF THE RAMP. SLOPE OF THE LANDING SHALL NOT EXCEED 1:48 (2%) IN ALL DIRECTIONS. 5. IN INSTANCES WHEN IT WILL BE TECHNICALLY INFEASIBLE FOR A PEDESTRIAN RAMP TO BE CONSTRUCTED TO FULL AND STRICT COMPLIANCE WITH ADA STANDARDS, THE PEDESTRIAN RAMP MUST BE INSTALLED TO PROVIDE ACCESSIBILITY TO THE MAXIMUM EXTENT FEASIBLE. ALTERNATIVE DESIGNS SHALL BE APPROVED BY THE PUBLIC WORKS DEPARTMENT PRI01 TO CONSTRUCTION. 6. PEDESTRIAN RAMPS SHALL BE A MINIMUM OF 60 INCHES WIDE. ;RETROFIT PEDESTIAN RAMP DETAIL STAB DESIGN TOP OF CURB GRADE 0.2 FT BELOW 0.2 FT BELOW DESIGN PAVEMENT GRADE PAVEMENT GRADE TOP OF CURB GRAD 0.2 FT BELOW DESIGN TOP OF CURB GRADE (SET TO LONGITUDINAL STREET GRADE) WWF 4' 4' 4' REINFORCE SUPPORTEDWITH #3 REINF RCING 1BARS AT648" ON CENTER EACH WAY ON 3" HIGH CHAIRS 2. CONSTRUCT PRIOR TO PAVING. CONCRETE CURB INLET APRON DETAIL 233 0 z 0 w a STREET STANDARD DRAWINGS AND NOTES ROUND CONCRETE VALVE COLLAR ALTERNATE SQUARE CONCRETE VALVE COLLAR — #4 REBAR CENTER HORIZ. AND VERT. VALVE BOX CONTROL JOINT, TYP OF 4 AROUND CONCRETE MANHOLE COLLAR ALTERNATE SQUARE CONCRETE MANHOLE COLLAR MANHOLE RING AND CASTING I REBAR CENTER 1RIZ. AND VERT. ROL JOINT, TYP I r T #4 REBAR CENTER OF 4I ` HORIZ. AND VERT. PLAN VIEW SECTION VIEW NOTE: 1. ALL VISIBLE EDGES AND JOINTS SHALL BE ROUNDED WITH A 1/4" RADIUS EDGING TOOL. 2. CONCRETE SHALL BE M-4000 WITH 3/4" MAX. AGGREGATE, MIN. 28 DAY STRENGTH OF 4000 PSI, 6% +/- 1.5% AIR ENTRAINMENT AND MAX SLUMP OF 4". 3. ALL JOINTS SHALL BE SAW CUT. CONCRETE COLLAR DETAILS TYPICAL ROAD SECTION PER TRENCH DETAIL 12" MIN VALVE BOX K-3/8" i; CONCRETE VALVE z .g f I ' ; BOX COLLAR z #4 REBAR CENTER HORIZ. AND VERT. TYPICAL ROAD SECTION PER TRENCH DETAIL MIN /—CON F'--I / BOX VALVE 1. BASE MATERIAL SHALL BE A CRUSHED GRAVEL, —3/4" DIAMETER COMPACTED TO 95% DENSITY (+/— 3% OPTIMUM SIDEWALK SHALL BE MOISTURE) PER AASHTO T-99, 6" MIN. AT DRIVEWAY 2_ CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM SIDEWALK AGGREGATE, MINIMUM 28—DAY J. STRENGTH OF 4000 PSI, 6% is ENTRANEMfENT, AND MAXIMUM �� COt R€1E St AIL SLUMP OF 4 11. SIDEWALK 6" CONCRETE W 6" BASE MATERIAL 5' 2% MAX APRON i BASE MATERIAL SECTION A —A ST.19 DRIVEWAY DETAIL SIDEWALK AT CURB 234 STREET STANDARD DRAWINGS AND NOTES a SIDEWALK SHALL BE 6" MIN. AT DRIVEWAY 6RNEWAY' ' �I ' F�ONCRETE RAMP RAMP SIDEWALK 1:42 6' VARIES -•"A 1. BASE MATERIAL SHALL BE CRUSHED GRAVEL, -3/4" DIAMETER COMPACTED TO 95% DENSITY (+/- 3% OPTIMUM MOISTURE) PER AASHTO T-99. 2. CONCRETE SHALL BE M-4000 WITH 3/4" MAXIMUM AGGREGATE, MINIMUM 28-DAY STRENGTH OF 4000 PSI, 6% +/- 1 1/2% AIR ENTRANEMENT, AND MAXIMUM SLUMP OF 4" SIDEWALK 6" CONCRETE W 6" BASE MATERIAL 5' 41:481 MAXI 41 BASE MATERIAL SECTION A -A DRIVEWAY DETAIL SIDEWALK AT CURB "4 FT PUBLIC R/O/W UTILITY BENCH ` 4" ASPHALT 12" CULVERT WITH FLARED END SECTION CE SWALE _ _ _ - _ DELINEATOR POST AT CULVERT ENDS SHOULDER #`-SAW CUT FOR PAVING JOINT AT EXISTING ASPHALT 3 A D 3, SAW CUT FOR PAVING JOINT AT EXISTING ASPHALT 8% MAX 2R MIN EXISTING RURAL ROAD ari YR-a'f.e— 4dL'.Ca�vS'u?n 12" CULVERT WITH ✓4" ASPHALT FLARED END SECTION 6" CRUSHED BASE O* SEE ROAD CONSTRUCTION GENERAL NOTES FOR MATERIAL SPECIFICATIONS 235 SPECIAL PROVISIONS SECTION 02600 WATER DISTRIBUTION This page intentionally left blank SPECIAL PROVISIONS SECTION 02660 WATER DISTRIBUTION This special provision amends or supplements the Montana Public Works Standard Specifications, Sixth Addition — April, 2010. All provisions not amended or supplemented remain in full force and effect. Delete Subsection 2.2.B.4 of the Standard and Replace with the following: 4. Fittings a. Furnish fittings meeting the following; 1) Mechanical Joint Class 350 fittings meeting AWWA C153, latest edition, Ductile Iron Fittings for Water. Delete Subsection 2.2.B.6 of the Standard and Replace with the following: 6. Couplings a. Use pipe couplings meeting the following; 1) Ductile iron, mechanical joint solid sleeves, with a minimum 12 inch length. Delete Subsection 2.2.0 of the Standard and Replace with the following: C. Polyvinyl Chloride (PVC) Pressure Pipe 1. Furnish PVC water main pipe meeting AWWA C900 requirements, made to ductile iron O.D.'s for "Push -On" joints. Assure pipe joints are bell and spigot having an elastomeric gasket. Use DR 18 Class 235 pipe. Delete Subsection 2.2.1) of the Standard in its entirety: Delete Subsection 2.2.E of the Standard and Replace with the following_ E. Water Service Pipe 1. Use polyethylene pipe in water service line construction as specified in the contract documents and meeting the following specifications. a. Furnish service pipe of the size or sizes specified. Service lines are considered 2-inch size and under. Service lines over 2-inch size are considered as water mains and are specified and the applicable sections. b. Furnish and install the service pipe from the main according to the requirements of City of Kalispell Drawing W.2 City of Kalispell 02660 - 1 Water Distribution c. Polyethylene Service Pipe 1) Use pipe meeting AWWA Specification C901, "Polyethylene (PE) Pressure Pipe, Tubing and Fittings, 1/2 inch through 3 inch for Water" and ASTM PE 3406-3408. PE pipe to be pressure tubing meeting Table 6 requirements of said speciation. Use class 200 with DR of 7 Polyethylene pipe. Delete Subsection 2.3 of the Standard and Replace with the following: 2.3 TAPPING SPEEVES AND VALVES A. Use tapping sleeves meeting: 1. Split -body type with circular gasket forming a seal around the circumference of the outlet, being a Romac SST III, bolts shall be Core -Ten or Core -Blue, or equal as approved by the City of Kalispell Public Works Department. Delete Subsection 2.4 of the Standard and Replace with the following: 2.4 CORPORATION STOPS A. Furnish brass corporation stops, Mueller 300 Series ball valves. Delete Subsection 2.5 of the Standard and Replace with the following: 2.5 SERVICE CLAMPS A. Furnish Mueller BR2 Series service clamps. Delete Subsection 2.6 of the Standard and Replace with the following: 2.6 CURB STOPS A. Furnish curb stops, Mueller 300 Series ball valves. Delete Subsection 2.7 of the Standard and Replace with the following: 2.7 CURB BOXES A. Furnish extension type curb boxes having 6 '/z foot extended length, with stationary rod & pentagon brass plug. B. Furnish one of the following: 1. Mueller H-10306 for service lines 3/4-inch to 1-inch. 2. Mueller H-10310 for service lines, 1 '/4-inch, 1 '/z-inch or 2-inch. Amend Subsection 2.8.A of the Standard by adding the following: City of Kalispell 02660 - 2 Water Distribution 4. Furnish a Mueller Resilient Wedge Gate Valve, or approved equal for all valves 4 -inches through 12 — inches. Amend Subsection 2.8.13 of the Standard by adding the following: 4. Furnish a Mueller Lineseal Butterfly Valve, or approved equal for all valves 14 -inches and larger. Delete Subsection 2.10.B of the Standard and Replace with the following: B. Furnish Red Mueller Super Centurion 250 fire hydrants with 5-inch Storz adapter and two, 2 1/2 — inch hose connections. Assure hose nozzle threads meet ASA Specification B26 for National Standard Fire Hose Coupling Screw Threads, 7 '/z threads per inch. Furnish National Standard operating nut. Furnish hydrants opening counter clockwise and having and arrow on the hydrant top designating the opening direction. Delete Subsection 2.10.D of the Standard and Replace with the following: D. Furnish hydrants for 6.5 foot bury. Amend Section 2 of the Standard by adding the following: 2.13 METER PITS A. Furnish Mueller Thermo -coil meter pits for services up to I — inch, with dual check valve and composite center locking lid. B. Furnish Mueller EZ Vault or approved equal for services larger than I — inch, with dual check valve and composite center locking lid. Delete Subsections 3.4.A.1 & 2 of the Standard and Replace it with the following: 1. Perform hydrostatic and leakage testing in accordance with AWWA C600. Once the pipe is laid and backfilled, test for at least two (2) hours, all newly laid pipe, or any valved section, to a hydrostatic pressure of either, 1.5 times the working pressure or 125 psi, whichever is greater. 2. If tablet disinfection will be used, slowly fill the main with clean water. If continuous feed method will be used for disinfection, slowly fill the main with appropriately chlorinated water. Purge all air, and apply the test pressure using a pump hooked up so that the pressure and leakage can be measured. To purge the pipe of air during the test, it may be necessary to tap the pipe at its highest points if permanent air vents, water services, hydrants, etc. are not located at high points. Use corporation stops for this purpose. Furnish the pump connections, gauges, stops, and all necessary equipment for testing. City of Kalispell 02660 - 3 Water Distribution a. After reaching 20 psi in test section, turn off pump and verify pressure stabilizes. Pressure must stabilize for 30 minutes prior to continuing to the required maximum test pressure. b. Take special care when approaching the working pressure of connecting mains to ensure chlorinated or untreated water does not enter distribution system. A stop in the increase of water pressure, when the line pressure approaches the working pressure, is indicative of a leak through a connecting valve. If water pressure stops increasing once the connecting main working pressure is achieved or if line pressure continues to drop to working pressure once pump is stopped, test water may be entering distribution. Stop pump immediately and do not proceed until approval is given by Engineer. Delete Subsection 3.4.C.3.a of the Standard and Replace it with the following: a. Two (2) methods of chlorination may be used: the tablet method or the continuous feed method. Either method shall maintain a minimum disinfection contact time of 24 hours prior to flushing. Delete Subsection 3.4.C.3.a.3 of the Standard in its entirety. Amend Subsection 3.4.C.4 of the Standard by adding the following: b. Heavily chlorinated water flushed from the mains shall not be placed in storm sewer or sanitary sewer and shall be disposed of per DEQ Standards c. Contractor may flush heavily chlorinated water in two ways: 1. Flush main into a water truck with appropriate back flow prevention air gap and dispose of chlorinated water in environmentally friendly matter. 2. Dechlorinate flushed water to a concentration below 0.1 mg/L, before allowing water to enter storm sewer using methods approved by the Engineer. Dechlorination method must be submitted to Engineer for approval at least three (3) business days prior to flushing. Delete Subsection 3A.D.1 of the Standard and Replace it with the following: After final flushing and before the water main is placed in service, test a sample, or samples, collected from the main(s) for turbidity and organisms. Collect at least one sample from the new main at a maximum of 500 foot intervals. a. Two sets of tests shall be completed for every sample point: 1. One sample set shall be collected directly following final flushing. i. The Contractor shall provide all sample bottles and appurtenances necessary to take samples. ii. The Contractor shall collect sample(s) and mark the sample bottles. City of Kalispell 02660 - 4 Water Distribution iii. The City shall witness sample collection and deliver sample bottles to a certified testing laboratory of the Contractor's choice within Kalispell City Limits. iv. The Contractor shall pay for all costs associated with sample tests, including City personnel costs for repeated tests due to test failure or City personnel costs for any tests performed outside normal working hours. Normal working hours are (Mon — Fri 8:00 am — 5:00 pm). 2. After passing results of the first test are received, but no sooner than 24 hours following final flushing, the contractor shall take a second sample from the same location(s) as the first sample set. i. Sample procedure shall be the same as those in Section 3.4.D.1.a.1, above. 3. After passing results have been delivered to and approved by the City, the new water main may be placed in service. END OF SECTION City of Kalispell 02660 - 5 Water Distribution SPECIAL PROVISIONS SECTION 02720 STORM DRAIN SYSTEMS This page intentionally left blank SPECIAL PROVISIONS SECTION 02720 STORM DRAIN SYSTEMS This special provision modifies the corresponding Montana Public Works Standard Specifications, Sixth Addition — April, 2010. All provisions that are not amended or supplemented remain in full force. Amend Part 2 of the Standard by ADDING the following: 2.2 PIPE MATERIALS E. Polypropylene Pipe 1. Furnish Polypropylene Pipe produced as a twin wall pipe with smooth interior bore and corrugated outside wall formed with co -extrusion techniques. Assure that the material meets or exceeds ASTM F2736 and AASHTO M330 for pipes 12 inches through 30 inches and ASTM F2881 and AASHTO M330 for pipes 36 inches through 60 inches in diameter. 2. The normal laying length is a maximum of 20 feet except shorter runs are permitted adjacent to manholes, catch basins or other appurtenances. Assure each pipe length is marked with the size and code number. Assure that each pipe has a bell and spigot with rubber gasket. Make the rubber gasket joint using a rubber gasket compressed between the outer surface of the spigot and the inner surface of the bell. Make any field fabricated corrugated connections with corrugated coupling having split collar engaging at least two full corrugations. Assure all joints are watertight connections under all service conditions including, expansion, contraction, settlement and pipe deformation. 3. Furnish fittings as required of the same material, construction and joint design as the main sewer pipe. Amend Part 3 of the Standard by REMOVING SECTION 3.4 STORM DRAIN SERVICE LINE in its entirety: City of Kalispell 02720 - 1 Storm Drain Systems Amend Part 3 of the Standard by AMENDING the following: 3.2 TESTS A. Light Test(Visual) 1. Once the trench is backfilled, perform a light test between manholes to check alignment and grade of the pipe for displacement. The completed pipeline must permit a true circle of light to be seen from manhole to manhole. B. Leakage Test 1. Unless specified a leakage test will not be required. Any potential obvious and concentrated leaks, such as open joints, pinched gaskets, cracked barrels or bells will not be allowed. A leakage test pursuant to SECTION 02730 SANITARY SEWER COLELCTION SYSTEM, may requested by the ENGINEER upon questionable results from T.V. Inspection. Amend Part 3 of the Standard by ADDING the following: 3.2 TESTS D. T.V. Inspection 1. All storm drain mains shall be inspected using a television camera before final acceptance. A storm drain line is defective and unacceptable if (1) the alignment is outside the specified limits (2) water ponds in any section are equal to or greater than 2 times the grade tolerance specified herein under Section 02725.3.1.E.1 or (3) the pipe has visible defects such as open joints, pinched gaskets, cracked barrels or bells or similar defects. 2. Pay all costs incurred in repeat television inspections or television inspections performed solely for Contractor benefit. 3. Record all television inspections in a format acceptable to the Owner. Pull the camera through the sewer at 30 feet per minute maximum. If the camera is pulled by attaching to the hose of a hydraulic sewer cleaner, assure the hose is not active during the pulling process. END OF SECTION City of Kalispell 02720 - 2 Storm Drain Systems SPECIAL PROVISIONS SECTION 02730 SANITARY SEWER COLLECTION SYSTEM This page intentionally left blank SPECIAL PROVISIONS SECTION 02730 SANITARY SEWER COLLECTION SYSTEM This special provision amends or supplements the Montana Public Works Standard Specifications, Sixth Addition — April, 2010. All provisions not amended or supplemented remain in full force and effect. Delete Subsections 2.2A.2.a.2 & 3 of the Standard in their entirety. Delete Subsection 2.2.A.3 of the Standard in its entirety. Delete Subsection 2.2.13 & C of the Standard in its entirety. Amend Subsection 2.3 of the Standard by adding the following: F. Joint Seal 1. Furnish nine (9) inch minimum width exterior rubberized joint seals: a. Infi-Shield Gator Wrap b. Press -Seal EZ-WRAP C. MacWrap d. Riser -Wrap e. Equal product as approved by Public Works. G. Chimney Seal: 1. Furnish one of the following acceptable chimney seals: a. Whirly Gig b. Cretex External Chimney Seal C. Cretex Internal Chimney Seal d. WrapidSealTM Manhole Encapsulation System e. Equal system as approved by Public Works. H. Flexible Gasketed Joint 1. Furnish flexible gasketed joints for all pipe connections. City of Kalispell 02730 - 1 Sanitary Sewer Collection System Delete Subsection 3.4.C, D, & E of the Standard in their entirety. Delete Part 4 in its entirety. END OF SECTION City of Kalispell 02730 - 2 Sanitary Sewer Collection System GENERAL REVIEW CHECKLIST Project Name: Date: Submitted By: Reviewed By: Design Requirements No. Yes No N/A General Requirements G1 Designed by a MT licensed Professional Engineer G2 Plans, Specifications, Reports Stamped by MT PE G3 Design Submitted to MT DEQ for concurrent review G4 Roadways to be constructed to far property line G5 Utilities to be constructed to far property line G6 Easements provided for all (City Owned) roads and utilities G7 10' easement along lot front and side street lines for private utilities G8 All new utilities placed underground G9 Proposed Street Lights 2 feet or more behind curb G10 Survey Datum is NAVD 1988 G11 Coordinate System is MT State Plane, International Foot Engineer: Na License No. Firm Signature Date MT Professional Engineer's Stamp General Review Checklist WATER REVIEW CHECKLIST Project Name: Date: Submitted By:. Reviewed By:_ Design Requirements No. Yes No N/A Designed, constructed and tested in accordance with: W1 Circular DEQ 1 - Standards for Water Works W2 Montana Public Works Standard Specifications (Current Issue) W3 City of Kalispell - The Standards for Design and Construction (Current Issue) No. Yes No N/A Additional Requirements: W4 Design Engineer submitted report addressing fire and domestic flows W5 Design Engineer is MT PE and has stamped plans and report W6 Report includes flow test results at nearest hydrant(s) to development W7 Hydrant test shows static pressure W8 Hydrant test shows available flow at 20 psi residual pressure W9 Fire Flow Requirements determined by Kalispell Fire Department Construction and Material Requirements: No. Yes No N/A Isolation Valves: W10 Are not in gutter flowlines, sidewalks, travel route, multiple use path, or travel lane wheel path W11 On each leg of each tee or cross W12 At each intersection crossing W13 Butterfly Valves are Muller Linesea) or approved equal (C504) W14 Isolation Valves larger than 12" are butterfly valves W15 Gate Valves are Mueller Resilient Wedge Gate Valves (C509) W16 Tapping sleeves are Romac SST III or approved equal for 4" or greater W17 Valve Boxes are slip or screw type adjustment W18 Valve box collar is provided in accordance with drawing ST-18 Water Review Checklist No. Yes No N/A Water Pipe: W19 8" minimum diameter for mains W20 6" minimum diameter for fire hydrant lead lines (not exceeding 50 feet in length) W21 6" to 12" diameter are Class 150 (C900) PVC W22 Mains larger than 12" are Class 150 (C905) PVC W23 Fittings are Mechanical Joint Class 350 (C153) W24 Mechanical Joint Restraints are Megalug or approved equal W25 Thrust blocks are installed at all mechanical joint fittings W26 Detectable warning tape is a min. of 5 mil and 3" wide, conforming to APWA colors, and buried 12" - 24" below final ground surface W27 Toner wire is 14 ga solid core copper, appropriately insulated and spliced, taped at top of main, and brought to surface and accessible at valves. No. Yes No N/A Water Services: W28 Service line, valve and meter for each individual ownership W29 Service saddles are Mueller BR2 series or approved equal W30 Corporation stops are Mueller 300 Series Ball Valves or approved equal W31 Curb stops are Mueller 300 Series Ball Valves or approved equal W32 Fittings are Mueller Insta-Tite, 110 Series compression, or approved equal W33 Curb boxes are Mueller H-10308, cast iron extension, arch base, 1-1/2" ID upper, 6-1/2' length, w/ stationary rod and pentagon brass plug W34 Service lines up to and including 2" are PE (C901) W35 Service lines 4" and greater are Class 150 PVC (C900) No. Yes No N/A Fire Hydrants: W36 Are Red W37 Are Mueller Super Centurion Fire Hydrants W38 Have Storz adapter(s) with cap conforming to C502 W39 Spacing does not exceed 500 feet in residential, 300 in commercial, or 200 feet in industrial areas W40 Barrel is more than 2 feet behind top back curb W41 Barrel is more than 2 feet from edge of sidewalk W42 Placement approved by Fire Chief Water Review Checklist SANITARY REVIEW CHECKLIST Project Name: Date: Submitted By: Reviewed By:_ No. Yes No NA Designed, constructed and tested in accordance with: SA1 Circular DEQ 2 - Design Standards for Wastewater Facilities SA2 Montana Public Works Standard Specifications (Current Issue) SA3 City of Kalispell - The Standards for Design and Construction (Current Issue) No. Yes No N/A Additional Design Requirements: SA4 Design Engineer submitted written report for all improvements or additions. SA5 Design Engineer is MT PE and has stamped plans and report SA6 Design Report assesses the ability of existing mains to handle peak design flow from proposed improvements and the impact on the Wastewater Treatment Plant SA7 Minimum design contributing flows are 265 gal/day/ERU with a Peaking Factor of 3.05 or Design Peak Hour Flow of 0.56 gpm/ERU SA8 City Engineer may require sulfide generation analysis SA9 If dissolved sulfide exceeds 0.2 mg/I, non -corrosive linings and/or special lift station design may be required SA10 Watertight manhole covers are installed in locations where flooding may occur SA11 Valves and manholes are not located in gutter flowlines, sidewalks, boulevards, or the wheel path of traveled lanes No. Yes No N/A Lift Station Design Report Requirements SA12 Design Engineer submitted written report for new lift station or flows contributing to existing lift station SA13 Description of wet well, pumping system, and force main SA14 I Capacity of recommended pumps and potential for upgrading SA15 Map showing potential lift station service area SA16 Average and Peak Design Flows for project and potential service area SA17 Hydraulic capacity of the force main SA18 Reserve capacity of the lift station when proposed project is on line and at full capacity SA19 Pump run and cycle times for the average and peak design flows SA20 Strategies for improvements which may be necessary to accommodate future sewer extensions (i.e., increased storage, pumping, auxiliary power capacity) SA21 Pump selection process, including Engineer's calculations for Total Dynamic Head, Total Discharge Head, Net Positive Suction Head, and other pertinent pump selection criteria SA22 Designed pump operating curve on manufacturer's pump performance chart with the designed operating point clearly identified Sanitary Review Checklist CONSTRUCTION AND MATERIAL REQUIREMENTS: No. Yes No N/A Lift Station: SA23 Duplex system setup (two complete and independent pump set UPS) SA24 Pumps, moving parts and controls are above ground SA25 Pumps are self -priming, suction lift type SA26 Pumps are equal to those manufactured by Gorman Rupp Company SA27 Submersible 3" pumps or submersible grinder pumps may be considered based on required operating volumes and heads of proposed lift stations SA28 Emergency natural gas generator is supplied SA29 Generator is quieter than 65 dbA from 20' away SA30 Influent pipe to wet well is DIP, class 50 cement lined, one joint long, and spigot extends 6" into the wet well beyond the interior wall. SA31 Has hour meter SA32 Has suction pressure gauge tap and valve for each pump SA33 Has discharge pressure gauge tap and valve for each pump SA34 Amperage meters are installed on each leg of electrical wiring SA35 Controls include a pump run alternator (lead -lag alternator) SA36 Lightning protection is provided on electrical power supply SA37 I Primary level control system is a transducer or air bubbler SA38 Backup level control system is encapsulated mercury float switches SA39 Engineer may request list of up to 3 lift stations of proposed type, in service for at least 5 years. City reserves right to accept or reject the proposed lift station. No. Yes No N/A Lift Station Access Roadway: SA40 A minimum 12 foot wide paved road provides access to the lift station SA41 The access road has a concrete approach between the sidewalk and the curb No. Yes No N/A Lift Station Fence: SA42 Fence is 6 ft chain link security fence SA43 Gate is 12 foot wide, double swing (two 6 foot leaves) Sanitary Review Checklist No. Yes No N/A Lift Station Building: SA44 Is gable -roofed SA45 Is constructed on shallow monolithic foundation with 4" floor SA46 A treated sole plate is firmly anchored to the monolithic foundation SA47 Finished floor to ceiling is 8 feet SA48 Roof slope is 4:12 SA49 Lap siding has 7" reveal SA50 Wall sheathing is 1/2" OSB SA51 I Roof sheathing is 5/8" OSB SA52 Shingles are 30-year, 3 tab SA53 Door is 3068 steel with deadbolt lock SA54 Ceiling is 5/8" unfinished gypsum board SA55 Wall studs are 6" SA56 I Interior siding is T-111 SA57 Wall insulation is R-19 minimum SA58 Ceiling insulation is R-49 minimum SA59 All other incidental items as required SA60 I Heating system is provided SA61 Lights are ceiling mounted industrial lights in cage SA62 Exterior yard lighting is provided SA63 Building plans have been submitted by Design Engineer to Public Works for review No. Yes No N/A lift Station Alarm System: SA64 Detects power interruption SA65 Detects high water SA66 Detects motor temperature conditions SA67 Alarm signals are directed to on -site alarm monitor and telephone dialer (Mission Communications Model M-110 [20 hp and smaller) or M-800 [larger than 20 hp]) No. Yes No N/A Gravity Sewer Main: SA68 Minimum Diameter of gravity main(s) is 8" SA69 Material is SDR 35 PVC SA70 Are deep enough to prevent freezing (6 foot) SA71 Shallow mains are insulated as necessary to prevent freezing (one trench wide layer of 2" blue board per foot below minimum cover) SA72 There are no storm water connections Sanitary Review Checklist No. Yes No N/A Oil/Water Separators: SA73 Oil/Water separator(s) is installed for automotive facilities, paint shops, dealerships, gas stations, equipment degreasing areas, and other facilities generating waste water with oil and grease content to be maintained on site. SA74 Oil/Water separator(s) for commercial/industrial processes is(are) sized based on analysis of wastewater characteristics with the discharge directed to the sanitary sewer system. SA75 All oil/water separators are fitted with standard final -stage sample box and spill absorbent pillows SA76 Oil/water separators are commercially manufactured and sized for the facility No. Yes No N/A Force Mains: SA77 Detectable warning tape is a min. of 5 mil and 3" wide, conforming to APWA colors, and buried 12" - 24" below final ground surface SA78 Toner wire is 14 ga solid core copper, appropriately insulated and spliced, taped at top of main, and brought to surface and accessible at valves. SA79 Toner wire installed for burst processes is 1/4" steel toner cable No. Yes No N/A Sewer Services: SA80 Service line is provided for each individual ownership SA81 Stub -outs are marked according to SAA SA82 There are no stormwater connections No. Yes No N/A Manholes: SA83 Cover is as shown in drawing SA.8, or approved equal SA84 The cover is marked "SANITARY" or "SANITARY SEWER" SA85 Conforms to drawing SA.3 SA86 Manhole Collar is provided meeting drawing ST.18 Sanitary Review Checklist STREET REVIEW CHECKLIST Project Name: Submitted By: Reviewed By:_ No. Yes No NA Designed, constructed, and tested in accordance with: ST1 Montana Public Works Standard Specifications (Current Issue) ST2 City of Kalispell - The Standards for Design and Construction (Current Issue) ST3 Manual on Uniform Traffic Control Devices ST4 The Subdivision Regulations of the City of Kalispell No. Yes No N/A Additional Requirements: ST5 Design Engineer is MT PE and has stamped plans and report ST6 Design is Approved by City Engineer No. Yes No N/A Traffic Analysis: ST7 Analysis has been provided for development if over 300 vehicles per day contribute to the City street system ST8 Professional Traffic Operation Engineer submitted and stamped the analysis ST9 The report indicates current traffic conditions for all impacted roads and Level Of Service (LOS) for each road ST10 The report identifies all negative impacts and details a mitigation plan to maintain the predeveloped LOS ST11 The analysis considers bicycle and pedestrian traffic ST12 The analysis is in accordance with the MDT requirements and national standards (Chapter 41 of Traffic Engineering Manual) No. Yes No N/A Cul-de-sacs: ST13 Dead end streets terminate with a cul-de-sac ST14 Temporary cul-de-sac size is approved by the Fire Chief and City ST15 Cul-de-sacs are less than 600' in length ST16 Radius is 47' to back of curb and 58' to right-of-way ST17 A 6' boulevard is provided SA18 A 5' sidewalk is provided No. Yes No N/A Streets: ST19 Alignments have adequate sight distances (See AASHTO Design Standards) Street Review Checklist No. Yes No N/A Collectors and Arterials: ST20 Are designed for a speed of 35 mph in accordance with the latest edition of AASHTO A Policy on Geometric Design of Highways and Streets ST21 Locations comply with Kalispell Growth Policy or any other plans adopted by Flathead County Board of County Commissioners and/or the City of Kalispell ST22 Frontage roads serve driveways and approaches rather than accesses from Collectors and Arterials ST23 Locations comply with Kalispell Area Transportation Plan. [MC 28.03.14.E] No. Yes No N/A Street Name and Traffic Control Signs: ST24 Streets aligned with existing streets are named the same as the existing street [MC 28.03.14.P] ST25 Installed at each intersection. ST26 Names have been approved by Public Works. ST27 Meet requirements of MUTCD. ST28 Constructed according to Detail ST.12 in Design and Construction Standards. No. Yes No N/A Street Lights: ST29 Are provided on all streets within a subdivision ST30 One corner light is provided for a two lane street intersection ST31 Two corner lights, placed diagonally are provided for four or more lanes. ST32 Light is provided for each mailbox group, bus stop location, and pedestrian path intersection. ST33 Light fixtures are full cut off as defined by Illuminating Engineering Society of North America (IES) ST34 Fixture type is FEC's standard full cut-off cobra head with Type III distribution ST35 Pole is FEC's standard 30 foot pole mounted to concrete pole bases ST36 Lamps in commercial areas are 200W HPS, poles spaced at 200 feet maximum ST37 Lamps in residential areas are 100W HPS, poles spaced at 250 feet maximum ST38 Lights are staggered to each side of the street. ST39 For 4 or more lanes, maximum spacing is decreased by 50% ST40 15% spacing variance is allowed if approved by Public Works ST41 Roads with sharp turns meet the illuminance and illuminance conformity of Table 3 ST42 Privately owned and maintained lights meet the minimum standards of Table 3 Street Review Checklist No. Yes No N/A Street Intersections: ST43 Intersect at 90' if possible, but never less than 75° for a distance of 60' measured from centerline to right-of-way line of intersecting. ST44 No more than two streets intersect at one point. ST45 Two streets meeting a third street from opposite sides, meet at the same point and their centerlines offset by at least 125' for local roads and 300' for collectors. ST46 Maximum straight tangent grade does not exceed 2% for 60' as measured from edge of transverse pavement edge to allow for stopping, starting and stacking distances. ST47 Minimum back of curb radii at intersection is 20' ST48 Provide a minimum sight distance of 150'. No. Yes No N/A Alleys: ST49 Provided for residential single family lots less than 50' in width. [MC.28.03.15.8.1] ST50 Provided for duplex or townhouse developments with street frontage density of 40' per unit or smaller ON AVERAGE for any block. [MC.28.03.15. B.2] ST51 Provided for lots adjacent to an existing or future collector street. [M C.28.03.15. B.3 ] ST52 Have a minimum 20' right-of-way width and 20' paved surface width in commercial areas. [MC.28.03.15.C.1] ST53 Have a minimum 16' right-of-way width and 12' paved surface width in residential areas [MC.28.03.15.C.2] ST54 Are open at both ends. [MC.28.03.15.C.3] [Ord. 1707, 12-19-2011] No. Yes No N/A Permanent Dead End Streets (Discouraged, Used Sparingly when all else fails): ST55 Does not exceed 600 feet from intersecting street centerline to center of cul-de-sac or approved turn around. [MC.28.03.14.C.1] ST56 Termination as approved by the Fire Chief [MC.28.03.14.C.2] ST57 Cul-de-sac termination is designed as described in cul-de-sac section of checklist. [MC.28.03.14.C.2] ST58 Hammerhead termination is on a dead-end street shorter than 150' long. [MC.28.03.14.C.2.b] ST59 Hammerhead travel surface extends 40' to the right and left of centerline of primary street. [MC.28.03.14.C.2.b.i] ST60 Hammerhead travel surface is a minimum of 20' wide [MC.28.03.14.C.2.b.ii] ST61 Another turn -around design as approved. [MC.28.03.14.C.2.b.iii] ST62 Turn -around may be waived if dead-end street is less than 110' long. [ M C.28.03.14. C.2. b. iv] Street Review Checklist No. Yes No N/A Sidewalks: ST63 Width is greater than or equal to 5 feet. [MC.28.03.16.C] ST64 Sidewalks are separated from the roadway by a landscaped boulevard or open space. [MC.28.03.16.F] ST65 A 2 inch sleeve is placed under the sidewalk to serve each lot for allowing convenient access for irrigation lines in the boulevard. The sleeve is 5 feet on either side of the driveway edge or marked with a stamp in the concrete. [MC.28.03.16.G] ST66 Will be kept free of snow, debris, brushes, etc., by adjacent property owner or HOA [MC.28.03.16.J] ST67 Sidewalks are designed in per AASHTO guidelines and meet the most current version of ADA Standards. [28.03.16.L] No. Yes No N/A Bikepaths/Pedestrian Paths: ST68 Width of asphalt path is greater than or equal to 10 feet [MC.28.03.16.D] ST69 Width of concrete path is greater than or equal to 8 feet [MC.28.03.16.E] ST70 Entity responsible for maintenance is identified at time of preliminary plat approval. [MC.28.03.16.K] ST71 Meet AASHTO Guide for the Development of Bicycle Facilities and Guide for the Planning, Design and Operation of Pedestrian Facilities most current versions. ST72 If serving as an emergency or maintenance route, it accommodates HS-20 loading. ST73 No catch basins, valve boxes, curb boxes, or other utility appurtenances are located within the travel path. ST74 Path signage meets MUTCD CONSTRUCTION AND MATERIAL REQUIREMENTS: No. Yes No N/A Asphalt Surface: ST75 Materials are to be tested in accordance with MPWSS 02510. Densities and thickness are to be measured by the core method. ST76 Design thickness is not less than 4 inches No. I Yes No I N/A Sub base: ST77 Is crushed stone in accordance with MPWSS 02234 ST78 Is 3" minus material with at least one fractured face. ST79 Larger material may be approved on a case by case basis, with at least one fractured face. Street Review Checklist N -9 Lf g e 53 z z .4 a 14 .4 a W s. Street Review Checklist STORMWATER REVIEW CHECKLIST Project Name: Date: Submitted By: Reviewed By: No. Yes No NA Requirements SW1 Stamped and dated construction drawings and design report are provided. SW2 A geotechnical site characterization is provided, if required. SW3 Water quality treatment is provided for this first 0.5 inch of rainfall on the site, and calculations are included. SW4 A completed wetland checklist is included. SW5 Drainage basin maps are provided which clearly label each drainage basin. SW6 Time of concentration routes for each segment are provided and clearly labeled with calculations. SW7 Check that all storm sewer pipes are sized to handle the 10-year storm event. SW8 The design water surface for flood control facilities is the 100-year post developed water surface elevation. SW9 The total discharge rate leaving the site shall be limited to pre -developed rates. SW10 All orifices are at least three inches. SW11 Check discharge locations. Stormwater runoff must be discharged in the same manner and at the same location as in the pre -developed condition. SW12 Culverts are designed to convey the 100-year design storm. SW13 For stormwater facilities outside of the public road right-of-way, the project owner shall provide for the financial means and arrangements for the perpetual maintenance of the drainage facilities. SW14 Check for offsite waters coming onto the site. Provisions need to be made to receive and pass offsite waters. SW15 A down -gradient analysis has been completed and is provided. SW16 Pond bottoms are located at least 0.5 feet below the outlet to provide sediment storage. SW17 The proposed stormwater facility meets the setback requirements as outlined in the Standards for Design and Construction. SW18 Calculations are provided to show that the pond will drain completely within 72 hours (unless it is a wet pond). SW19 Interior pond side slopes are not be steeper than 3HAV. SW20 An emergency overflow spillway is provided to bypass the 100-year developed peak flow. SW21 Fencing is provided if required by the Design and Construction Standards. SW22 T Pipes are designed to have a self-cleaning velocity of 2.5 ft/sec. Stormwater Review Checklist No. Yes No NA Requirements SW23 The HGLs are provided to show 0.5 feet of freeboard to the top of grate or cover in catch basins or manholes. SW24 Wherever two pipes of the same size meet at a junction, the downstream pipe shall be placed with its invert 0.1 feet below the upstream pipe invert. When two different sizes of pipes are joined, pipe crowns shall be placed at the same elevation. SW25 Inlet spacing does not exceed 400 feet. SW26 Gutters have a minimum longitudinal slope of 0.5%. SW27 The non -flooded width has been evaluated at low points, proposed inlet sections, and intersections. Bypass flow shall be limited to 0.1 cfs at intersections and at the project boundary. SW28 Catch basins, inlets, and storm manholes shall have a minimum 24 inch sump below the lowest pipe invert elevation. SW29 Inlet grates are depressed no more than one inch. SW30 Grate inlet capacity calculations are provided using a 35% clogging factor. SW31 An operation and maintenance manual is provided for all facilities associated with the stormwater system. SW32 A maintenance agreement is signed and included. SW33 A maintenance access road is provided when the stormwater facility is located eight feet or more from an all-weather, drivable surface. Stormwater Review Checklist Immanuel Lutheran - COMMUNITIES - March 11, 2015 Mr. Doug Russell City Manager City of Kalispell 2011st Avenue East Kalispell, MT 59901 Doug Russell, Immanuel Lutheran Communities supports the proposed changes to the City of Kalispell Standards for Design and Construction currently under review. We are currently in the planning phases of a five -phase renovation and expansion of our Kalispell Campus. The proposed project will require improvements to the existing stormwater system to meet City standards. The proposed standards will give us greater flexibility in our planning efforts by allowing underground stormwater detention and reducing surface impacts of stormwater facilities. The change in these standards is vital to completing our project as planned without reducing the size of buildings or parking areas. Sincerely, Jason R. Cronk CEO CC: Ms. Suzie Turner, PE, Public Works Director 185 Crestline Avenue Kalispell, MT 59901 Phone: (406) 752-9622 Fax: (406) 7S2-9602 ilcorp.org FAMILY OF SERVICES: Residential Living I Assisted Living I Memory Support 1 Rehabilitation I Long-term Skilled Nursing (E1�PPn(IFT�IINI�T�V r Keith Haskins Senior Civil Engineer City of Kalispell 201 1st Avenue East Kalispell, MT 59901 Dear Keith, I appreciate the opportunity to comment on available sewer main products for use in the City of Kalispell. Attached is a chart comparing the three PVC sewer pipes that have been on the market for decades with a new polypropylene sewer product. Please take a minute to look and compare them yourself. ASTM D-3034 and F679 are solid wall PVC pipes, F794 and F1803 are both profile wall PVC pipes and the last two are the new polypropylene profile wall products You will see that --by specification - PP Sewer has lower tensile, lower modulus, lower impact strength, lower flattening requirements, thinner walls, worse flow and a fiberglass or stainless steel band to stiffen the bell so the gasket will compress and attempt to seal the joint. Thermal expansion/contraction of PP Sewer is twice that of PVC-- and by specification the product must be dark gray or black, compounding the issue on hot summer or cold winter days. I have read the PP Sewer spec in detail and noticed references to "Slow Crack Resistance", "Creep Rupture Strength" and "Creep Modulus". None of these are referenced in PVC Sewer Specifications as the PVC material does not exhibit tendencies to "Crack, Creep and Rupture". I also dug out the chemical resistance charts and noticed polypropylene has lower resistance to Diesel and Detergents than PVC and found polypropylene is "Not Recommended" in the presence of any gasoline where PVC's ratings range from "Excellent to Fair". When Diamond, Contech, Royal, and ETI introduced Profile Wall PVC, the almost universal comment by installers was "It's more brittle than solid -wall PVC". This is because even though both solid wall and profile PVC have minimum impact strengths of 220 ft/lbs., solid wall greatly exceeds the minimum where profile simply meets the requirement. Since installation techniques generally put any product to this test, I wonder what installer comments will be with a pipe made to a 140 ft./lb. minimum requirement? Technology and new products come and go. It seems that the new products that "stick" are the ones that provide equivalent or better performance over traditional products at lower cost. Occasionally, a new product that has inferior performance characteristics will stick in a market -for a while - due to price alone. Seldom do they remain viable once the owner has used them. That appears to be the marketing philosophy for this new polypropylene product as cheap pricing is being thrown out on projects for which it is not even in the specification. And as you are aware, there is a big difference between storm water and raw sewage. I bring these issues to your attention because PP Sewer is being represented as equivalent to PVC sewer products. Nothing could be further from the truth. Sincerely, AV*W14__) Dan Magers SPECIFIED PIPE 362 Eagle Bend Drive Bigfork, MT 59911 406-837-7288 Mobile 406-250-6159 Email dan@specpip.e..net Date: March 18, 2015 TO: Susie Turner, PE — Director of Public Works & City Engineer FROM: Keith Haskins, PE — Senior Civil Engineer SUBJECT: Responses to Comments on City Standards Received from 48 North A letter was received from Brett Walcheck with 48 North Civil Engineering Services on March 16, 2015. Following are key portions of his comments in italic text, followed by my bulleted responses. 1. "...the intent of Standards should be for the purpose of establishing an acknowledged measure for quantitative and qualitative value. In review of the current proposed Standards, especially the stormwater section, it appears as though this intent has been lost. In fact the stormwater sections of the Standards appear to read as though much of the information was extracted from a stormwater design engineering handbook. Maybe another way to further clarify this comment is to look at another engineering discipline such as structural engineering. I believe it can be understood by all, that structural engineering entails many compliance and safely issues. However the City of Kalispell does not get into creating a design manual that identifies a step by step process and calls out every equation. It basicallY1ust requires the engineer to adhere the latest adopted code and it is the designer's professional responsibility to achieve that goal. " • The stormwater section of the standards is different from the rest of the manual because according to the requirements of the MS4 permit, the City is responsible to "develop, implement, and enforce a Storm Water Management Program (SWMP) designed to reduce the discharge of pollutants from the permitted Small MS4 to the maximum extent practicable (MEP), to protect water quality, and to satisfy the appropriate water quality requirements of the Montana Water Quality Act ... The SWMP must include management practices, control techniques, systems, designs, good standard engineering practices, and such other provisions necessary for the control of such pollutants." • Sections for water, sewer, and streets refer to materials from other design manuals that are extensive and complete. i. Design for water systems in the Kalispell Standards refers to Montana Department of Environmental Quality (MDEQ) — Circular DEQ 1 — Standards for Water Works, a 141 page document that specifies the design parameters for water supply, treatment, and distribution systems. ii. Design for sanitary sewer systems in the Kalispell Standards refers to MDEQ — Circular DEQ 2 — Design Standards for Public Sewage Systems, a 225 page document that specifies the design parameters for sewage collection, lift stations, and treatment systems. iii. Design for roadways and walkways refer to the FHWA Manual on Uniform Traffic Control Devices (a 862 page document) and AASHTO Policy on Geometric Design of Highways and Streets (a 905 page document). These reference documents specify the design parameters for traffic control and street geometries. March 18, 2015 Susie Turner, PE Page 2 2. "I believe another comparison that should be made is looking at the required design standards for other cities that fall under the MS4 requirements. The closest comparison that I could see was the City of Billings Stormwater Design Standards which was about 150 pages. However in review of those standards, they appeared to be established under the same premises of given design alternatives to accommodate the many varying scenarios that occur during the engineering process. " • The City of Billings Stormwater Management Manual is a standalone document that does not cover any other City utilities, streets, or right-of-way design criteria. • There is no widely accepted State of Montana or Federal design document available to reference for stormwater which will meet minimum requirements for MS4 communities. If there were, the City would likely refer to those design references and modify them where appropriate for local design. However, the Montana MS4 communities do realize there is a need for a set of consistent Standards. To this end, MS4 communities (including Kalispell) are currently working toward this goal in conjunction with EPA. EPA is funding the development of a State of Montana Low Impact Development Best Management Practices manual. Currently, the manual is in preliminary stages and MS4 communities are meeting once a month to discuss the document along with other regulatory requirements. 3. "Therefore 1 believe if the City was to adopt these current proposed Standards, it should be on an interim process. Basically let them be utilized for a six month process and then obtain comments from Public. If there are any potentially needed changes, they can occur at a later date when the Standards have actually been utilized for a certain time period. " • Although this is an interesting idea, I believe it is difficult to make work. The process to get the Standards updated to this point has taken a about a year and a half. There were several internal reviews to correct errors and ambiguities of the current standards, meetings with field crews to incorporate their input, incorporation of input received during communications with other engineers through the plan review processes since the previous update, and communications with the Stormwater Advisory Committee. Design Standards from other municipalities were reviewed for content and format. Meetings were setup with material suppliers and other sources for mechanical treatment and underground detention systems. New products were investigated, and where appropriate, incorporated into the Standards. All of these items are important to the process of the update to the standards, and each one of them takes time. Additionally, the process includes a workshop with City Council to review proposed changes, the public comment period, and a month waiting period before official adoption. • Many developments occur in phases. Developers want to know what Standards they will be held to. For example, the expansion project for the Immanuel Lutheran Community is waiting to submit plans until the new Standards are adopted. Other developments want to know that their Phase 1 design will be held to the same requirements as their Phase 4 design. • It is important to give new development something secure to design and build to. The last time the Standards were updated was in 2009, nearly 6 years ago. However, 6 years is probably too long for an update. Rather than 6 years, a goal should be for new standards every 4 years. This gives development a secure time frame for their investment and gives engineers adequate time to use the updated Standards on multiple projects to evaluate their merit. March 18, 2015 Susie Turner, PE Page 3 4. "They should also account for many other things, such as sustainable design. An example of this is the requirement that all trench backfill is to be 3-inch crushed backfill material. This is requirement that dramatically increases cost and does not always achieve favorable results. There are times under certain soil conditions that the material should be replaced with imported material. However, at times it is actually less beneficial to the overall improvement because it creates the potential for differential settlement and it is also a waste on our natural resources. In order to supply this material it has to be extracted from an offsite quarry and then trucked and placed on site. This entire process also requires an extensive use of diesel fuel for excavators, tractors, dump trucks, and rollers. Please remember that the final objective of having a stabilized trench can be accomplished by simply performing the necessary compaction tests that are already required within the Standards. " • Native materials change with location and depth. As a project proceeds, soil types change and so do optimum soil contents and maximum dry densities which must be tracked by the testing firms providing quality control. Therefore, a single project with native backfill typically requires multiple soil proctors. If materials from one part of the project are mixed with materials from another part of the project, a new soil proctor must be performed, representative of the modified soil. All of these proctors tie the properties of the soils, and the required compactive effort, to the backfill used in the trench. Typically a field technician is making an educated guess on what type of soil is being encountered in the trench based on experience and visual characteristics. However, a slight mischaracterization of soil type can have a major impact on the proper compaction and moisture content. • Most of the soils in Kalispell contain plastic silts and clays, which are less granular and therefore, more moisture dependent for proper compaction. By using a single imported material, the moisture content, compactive effort, proper lift thickness, and other material characteristics stay the same throughout the entire project. This mitigates soil identification errors in the field and provides a consistent effort and end result. • Surface differentials can typically be identified in the winter due to the effects of frost heave. The frost heave in native soils is much more evident than the frost heave in the 3" minus imported gravels because the gravels are not plastic like much of the native materials. Oftentimes in the winter, the trenches from new construction are perceived as having settled, when in actuality the rest of the roadway has expanded due to frost. • Staff experience, even recently has been that imported backfill material, although more expensive than native backfill, provides the City the best end product. This helps to ensure that the City takes over a roadway that will have a proper operational and maintainable design life. • The City has also incurred great expense for street repairs, created from utility trench settlement, for multiple subdivisions designed prior to the adoption of the 2009 Standards' requirement for imported backfill. These subdivisions include West View Estates, Silverbrook Estates, Empire Estates, The Willows, Leisure Heights, Old School Station, Glacier Commons, South Meadows, Buffalo Commons, and multiple phases of the Ashley Park Subdivision. March 18, 2015 Susie Turner, PE Page 4 5. There are many other examples of these types of situations that occur within the standards but I believe the following standard says a lot in itself. Section 3.1.5 (Design or Construction Deviation) states the following: Design or construction deviations will only apply when minimum standards cannot be met or when the proposed item exceeds minimum standards as determined by the City Engineer. Deviations will not be considered on the basis of cost, "engineering judgment" or "professional opinion." This requirement is very similar to what engineers see in the design requirements found in the DEQ circulars for water and sewer which say, "Adequate justification for the deviation must be provided. "Engineering judgment" or "professional opinion" without supporting data is not considered adequate justification. " Deviations to the Standards should not be considered on the basis of cost. Minimum standards and material requirements create equity from one development to the next. The materials the City of Kalispell has selected as minimum allowable are reliable products that become assets to the City rather than liabilities. The minimum design standards ensure a safe and functional end product. Deviations to the standards should not be considered on the basis of "Engineering judgment" or "professional opinion". The standards have been developed based on the requirements of state and federal laws, requirements of the City's MS4 permit, references to design data, references to manufacturer data, experience of field crews, and the experience of engineering staff. A Professional Engineer's judgment or opinion in the private sector is bound to vary from the judgment or opinion of the Professional Engineers currently working in Public Works. A Professional Engineer in the private sector tends to work to make a project successful and profitable. A Professional Engineer in the public sector tends to work to make a project operational and maintainable. This very difference in paradigms requires the creation of minimum Standards to balance the City engineers from becoming too conservative in design requirements and to keep private engineers from becoming too focused on engineering around necessary costs. The public comment period is the time for discussion and incorporation of proposed changes to the standards based on Engineering judgment or professional opinion. In this update the City has incorporated multiple changes that incorporated engineering practices based on local engineer's judgement and professional opinions. a 71 TT IIr l (-lam z 201 IStAvenue East PO Box 1997 Kalispell, MT 59903 Phone: 406-758-7720 Fax: 406-758-7831 www.kalispell.com Ipublic_works MEMORANDUM Date: March 16, 2015 TO: Susie Turner, PE — Director of Public Works & City Engineer FROM: Keith Haskins, PE — Senior Civil Engineer SUBJECT: Responses to Comments on City Standards Received from Carver Engineers A letter was received from Tom Cowan and Andy Hyde of Carver Engineering today, just before the close of business. Following are their comments in italic text, followed by my bulleted responses. "In your memo to the City Manager, dated March 2, 2015, it states, "All of the proposed changes have been circulated throughout the local engineering, construction and development community.... " We can't speak for the construction and development community, but we believe your circulation through the engineering community was woefully inadequate. Perhaps Carver Engineering was not on your list of engineers to receive a copy of the proposed standards and any updates or subsequent correspondence. Andy Hyde was e-mailed a copy of the standards through his participation on a Stormwater Review Committee, but nothing was sent to specifically to Carver Engineering. We were only made aware of the March 16, 2015 public hearing from phone call last week from a local surveyor who was upset with your existing and proposed Stormwater drainage standards. " • According to our records, copies or links to the Draft Standards were sent via email to the following engineers and / or engineering firms: Morrison Maierle, AE2S, Jackola, Kurt Meyer and Hafferman, Carver, Apec, KLJ, Allied Engineering, Applied Water, Bruce Boody, CTA Group, Mike Fraser, HDR Inc, Manion Engineering, RLK Hydro, TD&H, WGM Group, and Robert Peccia and Associates. 2. "We, at Carver Engineering, need a lot more time to review and better understand what is being proposed in the 2015 updated standards. Unlike government employees, we in the private sector survive on billable hours in providing our clients with civil engineering services. We cannot take several days or weeks off to read, thoroughly digest and comment on 268 pages of standards. We can only do so if spread out over an extended period of time. If you received few comments from other engineers, it is not because they feel the proposed standards are adequate and acceptable, it is likely because they, like we, simply do not have enough time to review the voluminous material. " • An email went out to the Stormwater Advisory Committee on December 24, 2014. Andy Hyde with Carver Engineering received a copy of the draft standards. • An email went out to other local engineering firms on January 2, 2015. Tom Cowan with Carver Engineering received a link to the draft standards. • Since January 2, there has been a total of 73 days of review time. March 16, 2015 Susie Turner, PE Page 2 "What we have reviewed of the proposed stormwater drainage standards, we basically feel they are much like the existing 2009 standards, they are way overdone. There is simply too much textbook style dialogue that makes the standards difficult to read and comprehend. It is obvious the 2009 standards were copied from some other jurisdiction with little or no commonality to the topographical or weather conditions of Kalispell, and the proposed standards are simply an extension of those 2009 standards. The intent was not to simplify or make them more "user friendly", the intent, or at least the perceived outcome, was to add more layers of regulation and increase the amount of information that has to be generated and provided. " • The format of the Standards was updated to make the Standards easier to follow and cite. • Additional items were added in the appendices, such as Plan Submittal Checklists, updated City Standards, and City Utility Specific Special Provisions to modify MPWSS. These items were added to assist engineers in their design submittals. 4. "Has there been any cost impact analysis of the existing and proposed design and construction standards on the community? Not only to pay the engineer to obtain and provide all of the information, calculations and design detail required by the standards, but the cost to furnish, install, operate, and maintain the stormwater drainage improvements the standards mandate. I think the costs are staggering." • There has not been any cost impact analysis. A study to measure the financial impact of the Stormwater Regulations would be a direct cost to tax payers and have no effect on the requirement to implement a Municipal Separate Storm Sewer System (MS4) Permit. • The goal of the Stormwater Standards is to protect water quality as is required by the MS4 Permit the City manages. Although the implementation of stormwater improvements has upfront and long term maintenance costs for developments and the City, if not managed appropriately, the City can be fined for violations of the MS4 permit. 5. "It is apparent the City exempted itself from the requirements of the 2009 standards. Recently we worked for a commercial property owner in Kalispell who rebuilt a portion of their existing parking lot, replacing old deteriorated pavement and curbs with new asphalt and concrete in exactly the same location and exactly the same size. No additional impermeable area was created by the project, but the City's current storm water standards required that the property owner install an expensive storm water treatment unit in the existing drainage piping from the parking lot. At the same time, the City of Kalispell was paving existing gravel alleys in Kalispell. According to City standards, this alley paving project was subject to the same storm water pretreatment unit requirement on the City's receiving storm drainage piping. Our client insisted that we ask the City of Kalispell if they were installing a pretreatment unit for the alley paving project as the Mall had been required to install. The answer from Kalispell Public Works staff was "No, we are not installing a storm water pretreatment unit. How could we? It would be impractical. " March 16, 2015 Susie Turner, PE Page 3 As recently as the 2014 construction season, additional gravel alleys were paved in Kalispell without the required storm water system improvements, apparently under the same notion that the City standards are impractical. We suggest that a "practicality waiver" that gives sole discretion to the party paying for required improvements be written into the standards so that all parties, not just the City of Kalispell, can exempt themselves from these standards when they are impractical to meet. " • The City is not exempt from the MS4 requirements, but is required to comply with them in a different way. The City manages and maintains the MS4 permit which requires plan review of stormwater design, maintenance of stormwater facilities in the City right-of-way, street sweeping, leaf pickup, catch basin cleaning, outfall sampling, public education and training, illicit discharge enforcement, outfall inspections, annual reports, etc. • Additionally, the City does install WQ Treatment units on projects when they can be incorporated, which has been done for the Willows Stormwater Improvement Project and the South Meadows Drainage Improvement Project. • Recently, staff made a decision to split apart the Sylvan Hill maintenance project into two phases. Phase 1 will correct the deteriorating pipe and restabilize the roadway. Phase 2 will install a Mechanical Treatment Device to treat water prior to the outfall. This will require additional time and funding, but the end result will be improved downstream water quality and better operation and maintenance conditions for the downstream detention pond. I BU February 10, 2015 Comments Received on Draft Design and Construction Standards 1. Dave Steely — LHC Inc. — Comments received via phone call a. Special Provision — Section 02600 — Water Distribution i. Subsection 3A.D.1 — Should clarify that if a sample port is not available for contractor to take a bacteriological sample, the contractor will be responsible to install a temporary service and also remove it after the testing is completed. ii. Added the following text: "If sample location is not available, the Contractor shall be responsible to install a service saddle, corporation stop, and necessary service piping for sampling purposes at no cost to the City. After all testing is complete, the Contractor shall turn off and cap the corporation stop, and remove all service piping at no cost to the City." b. Special Provision — Section 02720 — Storm Drain Systems i. Subsection 3.2.1) — TV Inspection - Dave was concerned that the cost to pay for a video inspection of new mains would significantly increase the cost of construction. ii. I explained that the contractor is only required to pay for repeat television inspections. The first inspection is completed by the City prior to acceptance. If a defect is discovered, or if the test cannot be completed the first time (for example, pipe bedding in the pipe, etc.), then the contactor would be required to either hire a company to perform the inspection according to City requirements, or pay City crews to perform the repeat inspection. iii. Attempted to make the text clearer by bolding text as follows: "Pay all costs incurred in repeat television inspections or television inspections performed solely for Contractor benefit." 2. Tom Anderson, Doug Hammerberg — Glacier Precast — Meeting with City Staff a. Requested Con -Seal CS-212 be added to list of approved manhole joint seals. i. Added the product to the approved list based on review of the product. b. Concerned about the requirement for gasketed or booted joints being required at all storm manholes and inlet structures. There are circumstances, when gasketed or booted joints cannot be provided because of constructability constraints. This can be for a variety of reasons, but mostly due to precast mold limitations and barrel joints on structures being in conflict with design pipe penetrations. i. Added note to Storm Standard Details: "ALL PIPE CONNECTIONS NOT CONSTRUCTIBLE AS DETAILED SHALL BE SUBMITTED TO CITY ENGINEER FOR REVIEW. " 201 Is' Avenue East, P.O. Box 1997, Kalispell, MT 59903 —Phone (406)758-7720 — Fax (406)758-7831 www.kalispell.com Brandon Theis — Robert Peccia and Associates Inc. — via email on 2/2/2015 a. 4.2.1.F.I.c & 4.2.2.A.III.d.ii: On our Whitefish projects, we have been installing Hydromatic Separators on their street reconstruction project. Is WQ treatment something that the City would look at doing on a case -by -case basis on street projects or is it simply "off the table" and exempt? I'm not the biggest fan of Hydromatic Separators, but it has been nice on site development jobs up there that we have been able to show that the City is making attempts at providing WQ treatment on their projects. Not so much of a comment as an observation ... I think it is easier for the private sector to swallow the WQ treatment pill if they see the public sector setting a clear example. i. On the street reconstruction projects, we consider treatment devices on a case by case basis, but typically fulfill our obligations through our good housekeeping in the right-of-way (street sweeping, inlet cleaning, leaf pick-up, etc.) b. Chapter 4, Table 6: Is the ARC I Condition used anywhere in the standards or is it shown for reference only? i. For reference only footnote added to table. c. 4.6.1.C: What about subsurface filter systems such as the "Jellyfish". I think "Underground treatment facilities are not permitted" really ties our hands on tight sites. There are a bunch of underground filter systems that are really good .... as long as they are maintained. And that's my guess why this language is in there... nothing ever gets maintained. But, there are maintenance agreements in place on all these systems. Is this maybe more of an enforcement issue than a design methodology issue? I would just hate to see the city close this door. There are a ton of great subsurface systems out there that can do a lot of good on the WQ treatment. i. Text changed to say, "Underground treatment facilities are not permitted, except for those meeting minimum requirements of section 4.6.3Z" ii. Allows technologies approved by Technology Acceptance Protocol — Ecology (TAPE) and Technology Acceptance and Reciprocity Partnership (TARP) to be used. d. 4.6.2.C.I: Maybe make a clarification that this calculation needs to be on the ARC III Condition. I was wondering if calculating the CN value using the distributed method could be replaced with the composite method. I seem to remember that Ian and I have struggled with this in the past. i. Changed text to say, "The water quality volume is the runoff from the first 0.5 inches of rainfall from a 24 hour storm using Are HI condition, or as otherwise required by the current MS4 Permit." ii. Requirement for distributed method was removed. e. 4.6.3.B.II.a.i: Would a grass filter strip or stone/sand diaphragm or mechanical filter/separator system work for the WQ pretreatment requirement on a subsurface infiltration system? You would have a WQ flow then, not a volume. Reason I ask is that if a subsurface infiltration system is to be used, the reason is probably because there is not much room for treatment volume. i. Modified Standards to refer to section 4.6.3.F.VIII which discusses pretreatment options. Page 2 of 8 Lastly, I was wondering if the outfall BMP idea we spoke about last spring has gained any momentum. We were talking about some type of a program where money would be set aside to do regional treatment systems. Those systems could feasibly collect and treat more storm water for less money and the best part is that they would actually be maintained. Seems like a program like this could provide more "bang for the buck". i. Following is the response to Mr. Theis: "As far as the outfall treatment devices, we did discuss this idea, but didn't move forward with it at this time. There were several things to work through with that idea. One of the main issues is following our permit which requires developments to treat stormwater on -site. But there were also some logistical issues to consider like: • How to size a regional treatment facility that works at full build - out, but also with low initial use. • We have over 70 outfalls and most of them are hard to access. • With regional treatment, the responsibility is on the City to operate and maintain. There is no incentive for a development to follow good housekeeping guidelines on their site. • How do we collect money for a regional treatment device, and what happens with the untreated stormwater while funds build for the treatment site/device? The more we discussed it, the more complicated it got. The idea is good, and we have been able to do this on a couple of occasions (South Meadows, Willows subdivision, etc.), but even those sites were for individual developments. " 4. Toby McIntosh —Jackola Engineering — via email on 2/9/2015 a. Section 1.1.2 — I understand the intent of this section but my concern as a design engineer is how do we design for a standard that is not potentially in place until a future date. A thought would be to limit the length of time an approval is valid before construction begins. For example the DEQ water and sewer approvals are valid for 3 years before a resubmittal is required. i. This provision is to protect the City for projects that remain dormant for several years and then decide to move forward with the design as originally approved. ii. Section 3.1.6 states that the MFE approval will expire with DEQ's original design approval for construction. iii. No modifications were made to the Standards. Page 3 of 8 b. Sections 1.10.1 and 1.10.2 — Our surveyor was out, so I have not confirmed if this is an issue, but I wasn't sure what the survey laws or practices allow in terms of re -setting of property corners or perpetuating property corners. Can a surveyor file or record "bearing markers" for the purposes of reestablishing a monument or can a monument be replaced from these "bearing markers" without retracing the boundary? On section 1.10.2 can a plastic cap be used? I know the plastic caps for property corners are more common and if they are located under a riser and cover, they would be protected from damage. i. Contacted local Professional Land Surveyor (Ryan Mitchell), he suggested referencing the requirements of the State as follows: When a street is to be reconstructed, prior to any excavation, a thorough search shall be made for existing intersection monuments. If found, such monuments and any other survey monuments likely to be disturbed or destroyed, shall be preserved by or under direction of a Professional Land Surveyor in accordance with MCA 70-22-115. All monuments set shall meet the requirements of ARM 24.183.1101. Monuments set in pavement or concrete driving surfaces shall be placed inside of a cast iron monument box. c. Section 2.3.2C — I am assuming the daily reports are for only the City owned improvements and not the private lot development? i. Yes. The section applies to "all utility and roadway construction projects." d. Section 3.1.7E — Do you want international feet? It seems that we often use survey feet, but I would have to verify with our surveyor. i. Yes. The City uses International Feet units for the Montana State Plane Coordinate System. e. Section 3.4.4F — Is the City open to deviation requests on the 2% max grade leading into an intersection? It doesn't take much grade on a site to easily exceed 2% and visually 2% slopes appear pretty flat, especially over relatively short distances. i. AASHTO and MDT recommend a max of 3% for 75 feet to develop an adequate stopping distance landing for vehicles. This grade into an approach is based on "wet" road conditions and a deceleration rate of 11.2 W/s. For "icy" road conditions, deceleration rates are lower and the City errs on the safe side. The City requires a max 2% grade for 60 feet coming into an intersection. The grade is shallower, but the landing is also shorter. ii. A deviation from the Standards for this condition would need to be justified by the Design Engineer and approved by the City Engineer. f. Section 3.4.7 — Street Subbase — MPWSS section 02234 allows both crushed and uncrushed subbase material, while the City is requiring the crushed material with the fractured face. I have not spoken to local contractors to see if a crushed 3" minus is a commonly produced material so maybe having the fractured face is not a big issue. With proper gradations, my experience has been that the uncrushed material becomes well keyed when compacted. i. City Staff does not recommend a change to this requirement. Fractured faces do provide better interlock of aggregates. Additionally, if fractured faces aren't required, there is no way to verify the material has been screened for maximum size. Page 4 of 8 g. Section 3.4.9 — I am assuming that the requirement for sidewalk is only along the subject property's frontage on these streets? i. Yes. h. Section 4.1.3E — I understand the nature and intent of this section, the one thing that is a challenge (especially on small commercial lots) is that to develop a property and meet the flow control and water quality requirements in the manual, it is almost impossible to not concentrate flow to some extent. On larger subdivisions or larger properties where channel flow is likely to develop, this is a much easier criteria to meet. i. Yes, this can be a difficult provision if the development outflows to an undeveloped property. However, this provision is necessary to protect these adjacent property owners. ii. Typically, outflows are channelized, when connected into a downstream conveyance system. In this case, downstream property owners are protected and this is a non -issue. iii. No changes are recommended for this section. i. Section 4.2.1.E.IV —Is this just saying we can't get a deviation to "ignore" a section in the code? Because I know we often need deviations to the standards for newly developed sites (ie pipe size, slopes, setbacks etc). i. Yes. Deviations are only granted in accordance with section 4.2.1.G. j. Section 4.2.2.F (c & e) Exemptions — As you and I discussed, the City being exempt from the storm water requirements imposed on all other development doesn't seem appropriate when the requirements in these standards are a result of the EPA MS4 permit. Along the same lines, this section lists maintenance projects by the City that are exempt. Do these maintenance activities apply to privately owned infrastructure? i. The MS4 Permit for the City requires private developments and redevelopments to complete Water Quality treatment onsite. Likewise, the City is required to implement a Stormwater Program which includes "Good Housekeeping" such as street sweeping, leaf pick-up, and inlet cleaning; "Erosion Control" such as permitting, training, and implementation; "Illicit Discharge"; and "Public Education / Particiapation" such as school classroom education, carwash kits, educational mailings, and surveys. ii. Last year the City: 1. Removed about 3,000 CY of sweepings from the streets a. —250 dump truck loads 2. Picked up about 5,000 CY of leaves a. --415 dump truck loads 3. Cleaned 250 storm inlets 4. Trained employees on Pollution Prevention iii. The City isn't exempt from MS4 requirements, but is required to meet the requirements in a different way. The City works hard to meet these requirements. Page 5 of 8 k. Section 4.4.3.C.I Sub -level Structure Feasibility — This section requires a minimum of one boring per 10,000 SF. Is this the lot area? How does this compare to the minimum lot size in the City (i.e. more than one boring per lot per single family residence)? MT DEQ does allow for a reduction in the number test pits in septic field work based on certain criteria. Will the City consider a reduction in the number of test pits for larger developments? Does this 10,000 SF requirement apply to both subdivisions and commercial development? My thought is that a commercial development will often receive additional engineering work beyond the typical residential project (ie geotechnical investigations including recommendations for foundations, backfill, subgrade preparations, etc) and therefore requiring the monitoring of groundwater through a high water season may unnecessarily impact the often fast timeline commercial projects experience. i. The square footage pertains to the sub -level structure, not the lot. ii. The City will not consider a reduction in the number of test pits for large commercial developments. iii. The 10,000 square foot sub -level structure area applies to both commercial and residential. However, not many residential structures would have sub- level areas equal to or greater than 10,000 square feet. iv. Groundwater monitoring during seasonal high ground water conditions is necessary to determine if sub -level structures are feasible. v. No changes to the current text are recommended. 1. Section 4.5.1.0 —Similar comment to 4.1.3.E. i. See previous response. in. Section 4.5.3.E — The infiltration rates listed in the HSG classifications do not appear to correlate with typical infiltration rates in section 4.6.3.13 and what I would expect to see. i. Infiltration rates listed in the Hydrologic Soil Groups (HSG)is based on reference materials, and was listed for reference only. Soil group classifications should be based off of the Web Soil Survey. ii. Reference infiltration rates were removed from the HSG descriptions. n. Section 4.6.3.D.II.e — What is considered high concentration of oil and grease and how is this established? i. The design engineer and Public Works reviewing engineer will need to use engineering judgment to determine if high concentrations of oil and grease would be expected. Parking lots for a proposed vehicle or heavy equipment service shop may have higher expected oil and grease concentration than a clothing or office retail. ii. Staff does not recommend a change to this section. o. Section 4.6.3.D.VI.e —From my experience a 1" or 3/4" minus drain rock is likely a standard item from gravel suppliers. Standard products will be more cost effective. i. This hasn't come up as an issue in the past. ii. 3/8" pea gravel is readily available and will meet this requirement. p. Section 4.6.3.G.III.h Dry Swales —Is the 1.1 inch rain event referring to the 2009 WQV standard that has been reduced to 0.5 inches? i. Yes. The text in the Standard has been modified to reflect 0.5 inches. Page 6 of 8 q. Section 4.7.5.B.H.a — Depth to limiting layer is called out as >5 feet while the water quality section for infiltration facilities is listed as >3 feet. i. No change was made to the Standards. r. Section 4.7.6.A.III — I was happy to see that underground detention is being added to the manual, but to not allow infiltration in these systems is not appropriate in all situations. Again for commercial development this is much more critical than larger subdivision projects. To meet the planning and zoning requirements, typical parking layout criteria, and these regulations results in commercial projects are frequently squeezed for space. In urban drainage, infiltrating runoff is one way to reduce overall runoff volumes and discharge to surface waters. The requirement for water quality BMP's upstream of detention will help mitigate clogging of infiltration basins. Additionally, we often do not have City storm drainage infrastructure to connect to, therefore once you collect storm water and pipe it underground, it is often impossible to daylight to surface infiltration. I realize that not all sites are appropriate for infiltration, but with the requirements for drainage submittals, we feel the appropriateness of infiltration utilizing underground structures should be considered on a case -by -case basis. i. Most soils in Kalispell have relatively slow infiltration rates. Where infiltration rates are adequate, above surface facilities provide the best visual monitoring. ii. If there is no other choice for storm detention, the design engineer will need to show the soils are adequate for infiltration, adjacent properties are protected, structures are protected, and meet the other requirements for a design deviation as required in the standards. iii. A change in the text of the Standards is not recommended. s. Section 4.7.8.A.II — I am assuming that a drainage parcel is only required in subdivisions and not in a single lot commercial development. If this is the case, please condition the section. i. The section already referred to Section 4.10, but was made more specific by referring to 4.10.2 which explains that commercial projects typically do not require a drainage parcel unless more than one lot would be served by the facility. t. Section 4.7.8.B.VI — Some commercial properties are less than 200 feet wide and may not be able to maintain a 200 foot setback to a school etc. if located adjoining the property. Will the City review this on a case by case basis? i. If a development cannot meet this requirement, then fencing or some other safety measure would be necessary to deviate from the standard. u. Section 4.7.8.D.I —We feel that 3H:1V side slopes are acceptable. In the manual the dry swales, biofiltration, wetponds, and bioswales all allow up to 3:1 slopes. In review of the Stormwater Manual for Eastern Washington, they allow detention pond slopes up to 3:1. With a stability analysis they even allow for steeper. I agree if space exists to allow flatter slopes, this is better. i. Pond side slopes were increased from 4H:1 V max to 3H:1 V max. v. Section 4.8.4 — A general comment on culverts is the analysis should consider inlet and outlet conditions. If analyzed purely on Manning's flow, you may not be getting the controlling flow conditions. i. Flow control type was already listed in 4.8.4.B.H. ii. To make the required analysis clearer, added section f, requiring inlet or outlet flow control type. Page 7 of 8 w. Section 4.8.5.C.II — Are the HGL requirement of 0.5 feet freeboard applicable in the 100 year design events? I am assuming it isn't since the requirement is to design pipes for the 10 year event with consideration to the 100 year events. i. 0.5 feet of free board applies to the 10 year event. During the 100 year event, the non -flooded width of the roadway should be evaluated. x. Section 4.9.3.A.I — I am assuming that the "professional" referred to in ESC preparation applies to SWPPP Administrators? i. Added the following text to the Standards: "For projects greater than 1 acre requiring a state SWPPP, the ESC must be prepared by a certified SWPPP Administrator. " Page 8of8