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AWWTP FPU - March 2019 - FINAL Electronic Version(Image placeholder or color box) (Image placeholder or color box) (Image placeholder or color box) Kalispell AWWTP Facility Plan Update City of Kalispell March2019 Kalispell Advanced Wastewater Treatment Plant (AWWTP) Facility Plan Update for City of Kalispell Public Works Department March 2019 Mayor Mark Johnson Council Sandy Carlson, Ward 1 Kari Gabriel, Ward 1 Chad Graham, Ward 2 Wayne Saverud, Ward 2 Rod Kuntz, Ward 3 Kyle Waterman, Ward 3 Phil Guiffrida, Ward 4 Tim Kluesner, Ward 4 Public Works Director Susie Turner AWWTP Manager Aaron Losing The technical material and data contained in this document were prepared under the supervision and direction of the undersigned whose seal as a professional engineer licensed to practice as such in the State of Montana is affixed below. Rickey L. Schultz, Jr., PE Project Manager HDR Engineering, Inc. 700 SW Higgins Ave., Suite 200 Missoula, MT 59803 EXECUTIVE SUMMARY Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-i Contents Executive Summary ...................................................................................................................................... 1 1. Introduction ................................................................................................................................ 1 2. Effluent Limitations and Regulatory Requirements ................................................................... 1 Effluent Limitations .................................................................................................................... 1 Recent and Ongoing Nutrient Regulations................................................................................ 2 3. Basis of Planning ....................................................................................................................... 3 4. Existing Wastewater Treatment Facility .................................................................................... 7 5. Wastewater Treatment Plant Improvements Alternatives and Evaluation ................................ 8 6. Recommended Alternatives and Implementation Plan ........................................................... 10 Tables Table ES-1. Outfall 001 Effluent Limitations ................................................................................................. 2 Table ES-2. Anticipated General Variance Levels for Nutrients ................................................................... 3 Table ES-3. Current AWWTP Influent Flow Data1 ........................................................................................ 4 Table ES-4. Influent Wastewater Characterization1 ...................................................................................... 5 Table ES-5. Projected Flows and Loads ....................................................................................................... 6 Table ES-6. Alternatives Evaluation Criteria ............................................................................................... 10 Table ES-7. Capital Improvement Projects Schedule: Short-term (FY 19/20 to FY 23/24) ........................ 12 Table ES-8. Capital Improvement Projects Schedule: Near-term (FY 24/25 to FY 33/34) ........................ 13 Table ES-9. Capital Improvement Projects Schedule: Long-term (FY 34/35 to FY 38/39) ........................ 14 Figures Figure ES-1. Process Flow Schematic ......................................................................................................... 7 Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -ii This page is intentionally left blank. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-1 Executive Summary This executive summary briefly describes the contents of the Facility Plan Update, including conclusions and recommendations arising from the document. This plan is focused on the City’s advanced wastewater treatment plant (AWWTP) located on Airport Road, immediately west of the existing municipal airport in the southern portion of the city. Recent condition and capacity assessments of the wastewater collection system are completed by the City in a separate facility plan update. 1. Introduction The goals of this Facility Plan Update is to define the conditions of the existing infrastructure, evaluate growth trends and estimate future impact, describe improvements necessary to meet discharge permit requirements, protect water resources, accommodate existing users and future growth, and develop a capital improvements plan and financial program that will ensure the goals of the utility are accomplished. This plan’s recommendations are based on a detailed evaluation of feasible alternatives, with recommendations for improvements that are found to be the most cost-effective solutions to the City’s needs within a 20-year planning period. The primary objectives of this plan are to: • Update the facility flow and loading projections that correlate to more recent data provided by the City; • Evaluate each unit process for capacity and operational flexibility to show that adequate capacity exists to optimally treat the projected influent flows and loads throughout the planning period; and • Recommend process improvements needed to provide process unit redundancy, assure capacity is available for future wastewater flows, and the facility can meet future discharge permit limits. Implementation of recommended improvements is through a flexible plan that can be responsive to changing criteria and the City’s available resources. 2. Effluent Limitations and Regulatory Requirements The City of Kalispell AWWTP is authorized by the Montana Department of Environmental Quality (MDEQ) to discharge treated effluent to Ashley Creek. The permit became effective on August 1, 2015 and will expire on July 31, 2020. A summary of current permit limitations and anticipated regulations follows. Effluent Limitations During the term of the permit, discharge from the AWWTP shall, at a minimum, meet the effluent limits presented in Table ES-1. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -2 Table ES-1. Outfall 001 Effluent Limitations Parameter Units Average Monthly Limit 1 Average Weekly Limit 1 Maximum Daily Limit 1 BOD5 mg/L 10 15 -- lb/day 259 388 -- TSS mg/L 10 15 -- lb/day 259 388 -- E. coli Bacteria 2,3 cfu/100 mL 126 252 -- E. coli Bacteria 3,4 cfu/100 mL 630 1,260 -- Total Nitrogen 5 lb/day 397 -- -- Total Phosphorus as P 6 lb/day 9.9 -- -- Total Phosphorous as P 7 lb/day 25.8 -- -- Oil and Grease mg/L -- -- 10 Dissolved Oxygen Saturation Percent -- -- >75% 1. See Definition section at end of permit for explanation of terms. 2. This limit applies during the period April 1 through October 31, annually. 3. Report Geometric Mean if more than one sample is collected during reporting period. 4. This limit applies during the period November 1 through March 31, annually. 5. Calculated as the sum of Total Kjeldahl Nitrogen (TKN) and nitrate/nitrite as N concentrations. 6. This limit applies during the period July 1 through September 30, annually. 7. This limit applies during the period October 1 through June 30, annually. Recent and Ongoing Nutrient Regulations In July 2014 the Montana Board of Environmental Review adopted base numeric nutrient standards which were published by the MDEQ in Department Circular DEQ-12A. The AWWTP discharge is located in Ecoregion Level III Northern Rockies (15) which sets the numeric nutrient standards at: • Average Monthly Total Nitrogen Limit = 0.275 mg/L • Average Monthly Total Phosphorus Limit = 0.025 mg/L The limits stated above are effective from July 1st through September 30th. The City applied for, and received, a general variance from the stringent limits. However, the general variance is set to expire in 2034 and nutrient limits are expected to be lowered with each permit renewal (Table ES-2) until expiration of the variance. In addition to the numeric nutrient standards developed by MDEQ, a total maximum daily load (TMDL) for Flathead Lake has been developed. A TMDL establishes the maximum amount of a pollutant that a body of water, e.g., river, stream, or lake, can receive and still beneficially support agricultural, industrial, and recreational activities. TMDLs are developed on a watershed basis and can be issued for nutrients, temperature, or sediments depending on the listed impairment of waters within the watershed/basin. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-3 Table ES-2. Anticipated General Variance Levels for Nutrients Permit Renewal Year General Variance Level TN (mg/L) TP (mg/L) 2020 6.0 0.3 2025 4.0 0.07 2030 3.0 0.05 20351 0.275 0.025 1. General variance expires in 2034 and numeric nutrient standards must be met. Phase 1 of the Flathead Lake TMDL was completed in 2001 and recommended a 25% reduction in nutrient loading to the lake. Phase 2 of the Flathead Lake TMDL is still ongoing, which may require additional nutrient load reductions in Ashley Creek to meet annual load limits. Interim TMDL work for the Flathead-Stillwater planning area resulted in a nutrient, sediment, and temperature wasteload allocation for the AWWTP. The nutrient allocation defaults to the aforementioned numeric nutrient standards and references general variance pathway. The sediment waste load allocation is expected to be met by adhering to current discharge permit limits. A phased implementation plan was recommended regarding effluent temperature monitoring and possible action if necessary. The City is currently collecting flow and temperature data in Ashley Creek and the AWWTP effluent for analysis by MDEQ. 3. Basis of Planning An evaluation of the influent wastewater flows and wasteloads to the Kalispell AWWTP was conducted to establish a planning basis for development of future improvements at the facility. The flows and wasteloads are based on the existing environment, the population and land use in the service area, and infiltration and inflow to the collection system. Historical AWWTP data and population projections were provided by the City of Kalispell and were used as the planning basis for proposed improvements developed as part of the facilities planning effort. In addition to receiving wastewater from City of Kalispell customers, the AWWTP also receives wastewater from the Evergreen Water and Sewer District No. 1 (the District). The District entered into an Interlocal Agreement with the City to convey raw wastewater that shall not exceed 0.805 million gallons average daily flow to the Kalispell AWWTP. It should also be noted that the City of Kalispell has little industry and therefore there is a minimal amount of industrial load to the AWWTP. However, a pretreatment program is required by permit and the City monitors industrial discharges according to national standards. Table ES-3 provides a summary of AWWTP influent flow data for the period from 2012 through 2017. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -4 Table ES-3. Current AWWTP Influent Flow Data1 Year Min Day (MGD) Ave Day (MGD) Max Month (MGD) Max Day (MGD) 2012 2.08 2.73 3.851 5.02 2013 1.91 2.46 2.882 4.42 2014 2.04 2.72 3.773 8.51 2015 1.95 2.60 3.764 5.78 2016 2.06 2.64 2.985 4.49 2017 2.18 2.97 5.366 8.66 Average 2.04 2.69 3.777 6.15 1 Influent flows from Kalispell and Evergreen service areas. Water quality data for influent wastewater was analyzed to evaluate trends in wasteloads to the Kalispell AWWTP and provide a general wastewater characterization (Table ES-4). The parameters evaluated were generally within typical values. In order to evaluate the adequacy of the existing wastewater facilities to serve the projected population, and appropriately size and select process equipment for wastewater treatment facilities, characteristics of the wastewater must be evaluated. Parameters such as volumetric flow, organic strength, suspended solids content, and nutrient loading are evaluated. Based on population projections and per capita unit loadings, future flow and loading values were developed. The per capita unit loadings were combined with population and peaking factors to generate projections of future flow and loading (Table ES-5). Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-5 Table ES-4. Combined Influent Wastewater Characterization1 Parameter Unit Average Maximum Month Maximum Day BOD5 mg/L 267 371 699 TSS mg/L 220 305 680 TKN mg/L 43.9 51.9 54.5 NH4-N mg/L 29.8 46.1 55.1 NO3-N mg/L 0.29 0.69 2.73 TN mg/L 44.2 52.6 57.2 TP mg/L 5.0 7.2 8.8 Temp DegC 14.4 N/A 20.4 BOD5 lb/d 5,886 7,175 13,542 TSS lb/d 4,856 7,198 20,901 TKN lb/d 972 1,163 1,764 NH4-N lb/d 661 1,015 1,479 NO3-N lb/d 6.5 20 140 TN lb/d 979 1,183 1,904 TP lb/d 111 152 254 1 Characterization of Kalispell and Evergreen combined influent wastewater for 2012 - 2017. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -6 Table ES-5. Projected Influent Flows and Loads Parameter Unit 2018 2023 2028 2033 2038 Total Population Served by AWWTP N/A 29,375 32,432 35,808 39,535 43,081 Flow Average MGD 3.17 3.50 3.87 4.27 4.65 Max Month MGD 4.06 4.49 4.95 5.47 5.96 Max Day MGD 6.62 7.31 8.07 8.92 9.72 Peak Hour MGD 10.47 11.211 12.182 13.243 14.194 BOD Average lb/d 6,386 7,051 7,785 8,595 9,366 Max Month lb/d 7,210 7,960 8,789 9,703 10,574 Max Day lb/d 11,787 13,014 14,369 15,864 17,287 TSS Average lb/d 5,261 5,809 6,414 7,081 7,716 Max Month lb/d 6,681 7,376 8,144 8,991 9,798 Max Day lb/d 15,464 17,073 18,850 20,812 22,679 TKN Average lb/d 1,051 1,161 1,281 1,415 1,542 Max Month lb/d 1,146 1,265 1,397 1,542 1,680 Max Day lb/d 1,317 1,454 1,605 1,772 1,931 NH4-N Average lb/d 714 788 870 961 1,047 Max Month lb/d 801 884 976 1,078 1,174 Max Day lb/d 992 1,095 1,209 1,335 1,455 TN Average lb/d 1,062 1,172 1,294 1,429 1,557 Max Month lb/d 1,283 1,417 1,564 1,727 1,882 Max Day lb/d 2,065 2,280 2,517 2,779 3,029 TP Average lb/d 120 132 146 161 176 Max Month lb/d 137 151 167 185 201 Max Day lb/d 171 188 208 230 250 2 Peaking Factor of 3.15 3 Peaking Factor of 3.10 4 Peaking Factor of 3.05 1 Peaking Factor of 3.20 Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-7 4. Existing Wastewater Treatment Facility The City of Kalispell operates a biological nutrient removal (BNR) facility for wastewater treatment. The facility (Figure ES-1) discharges treated effluent to Ashley Creek. An evaluation of the existing capacity of treatment processes and facility equipment as compared to the projected flows and loads was conducted and areas within the facility requiring improvements were identified. Figure ES-1. Process Flow Schematic The following major process areas were identified as requiring further evaluation to address capacity issues, aging equipment, equipment redundancy, modification to meet future regulations, and/or operations and maintenance requirements: • Preliminary Treatment • Influent Pumping Station • Primary Clarification • Flow Equalization Basin • Secondary Treatment • Secondary Clarification • Effluent Filtration • Reaeration Basin • Anaerobic Digestion Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -8 • Sludge Thickening • Biosolids Disposal 5. Wastewater Treatment Plant Improvements Alternatives and Evaluation Potential AWWTP improvement alternatives for areas of the facility identified as deficient were evaluated based on the scoring criteria in Table ES-6. A recommended alternative is selected based on evaluation scoring. Construction cost estimates were developed for improvement alternatives. Actual construction costs will depend on a variety of factors such as the final project scope and market conditions at the time of project bidding. All project costs will be derived using the same level of estimating accuracy and, therefore, will be comparable. Cost estimates are Class 4 estimates and are normally expected to be within – 15 to +50 percent of the actual construction cost. The final cost of the projects will depend on actual labor and materials costs, actual site conditions, productivity, competitive market conditions, bid dates, seasonal fluctuations, final project scope, final project schedule, and other variables. Based on the alternatives evaluation, the implementation of the alternatives listed below is recommended. The recommended wastewater treatment facilities process improvements are related to the need for added process unit redundancy to better enable routine maintenance of unit processes, provide capacity during peak flow and loading events, or meet anticipated regulations. • Preliminary Treatment o Install Two New Influent Screens • Influent Pumping Station o Replace Two Existing Influent Pumps with Higher Capacity Pumps • Primary Clarification o Construct Two, 75-FT Diameter Primary Clarifiers • Flow Equalization Basin o Construct new EQ Basin to be converted to a Primary Clarifier in the future • Secondary Treatment o Convert Secondary Treatment System to a 5-stage process • Secondary Clarification o Install Dome Covers on Secondary Clarifiers • Effluent Filtration o Construct Tertiary Membrane Filtration (TMF) process • Reaeration Basin o Modify Existing Reaeration Basin and Cover Structure Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-9 • Anaerobic Digestion o Replace Existing Heat Exchanger, Install Second Heat Exchanger, and Replace Existing Sludge Recirculation Pumps o Construct Second Primary Digester • Sludge Thickening o Replace Existing DAFT Units with Rotary Drum Thickeners (RDTs) • Biosolids Disposal o Construct City Owned and Operated Composting Facility • Miscellaneous Improvements as Designated by the City: o Aeration Blower Evaluation Study o Sidestream Treatment o Biofilter Bed Rehabilitation o Chemical Room Modifications o Additional Standby Power for Equipment o Administration/Laboratory Building Expansion o Digester Chemical Feed System o Fermenter Condition Assessment o Effluent Management Plan o Replace Belt Filter Press o Effluent Temperature Mitigation Plan o Influent Piping & Diversion Structure Rehabilitation Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -10 Table ES-6. Alternatives Evaluation Criteria Evaluation Criteria Description Construction Cost • Estimated construction cost of the alternative Future Flexibility • Allows for potential future MPDES requirements • Allows for future growth O&M Requirements • Low complexity • Operational ease • Ease of automation • Reasonable maintenance • Reliability • Longevity • Compatible with existing facilities • Safe/low use of hazardous chemicals Implementation • Ability to logically phase expansion • Ease of construction • Ability to maintain operation during construction • Minimal permit requirements • Ability to fit on site • Compatibility with surrounding land uses Operational History • Technology or equipment has a proven performance history at other similar facilities • Meets current MPDES requirements City Staff Preference • Considers City staff preference for certain technologies, equipment, manufacturers, etc. Sustainability • Vehicular traffic • Hazardous chemicals • Public safety • Air quality impacts (non-odor) Noise or Odor Potential • Malodorous odor potential • Nuisance noise potential • Vector attraction potential 6. Recommended Alternatives and Implementation Plan Moving forward with improvements to the facility in a multi-phased approach, addressing the most critical improvements first, is recommended. A flexible implementation plan was developed to enable improvements to be implemented with changing criteria and the City’s available resources. The recommended implementation plan is designed to provide timely construction of the necessary improvements at the AWWTP, without creating an overly complex construction management program. Projects are placed into three time periods and one or more project classification. A. Project timing: 1. Short-term: 0 – 5 years (2018 – 2023) 2. Near-term: 5 – 15 years (2023 – 2033) Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-11 3. Long-term: 15 – 20 years (2033 – 2038) B. Project classification: 1. Renewal and Replacement Projects o Replacement of equipment that is at the end of its useful life o Miscellaneous improvements that would improve operations and maintenance of the facility 2. Growth Related Capital Projects o Capacity expansion of equipment or processes that approach their capacity limit within the planning horizon 3. Regulatory Required Projects o Improvements that are required to meet current or anticipated regulatory requirements Overall project costs include the total construction costs, but also an additional markup to estimate the costs of engineering design, construction contracting, construction management, project administration, and legal costs. Construction cost projections are made at a three percent annual escalation rate. The implementation plans presented in Table ES-7, Table ES-8, and Table ES-9 are for improvements recommended to occur within the 2038 planning horizon. The City’s existing wastewater system is funded through user charges which pay for on- going operations and maintenance expenses and modest facility improvements. An evaluation of potential changes in residential sewer rates has not been included as part of this facility plan update. The City currently has a request for qualifications for consultant services to conduct a water and wastewater rate study. The City will continue to evaluate their rate structures through that separate work effort. A key project implementation strategy is the method of funding and financing of recommended improvements. Pursuance of available low-interest loans and grants to offset the cost of the wastewater treatment plant improvement projects is recommended. The expected methods of financing the improvements recommended in this plan include the use of cash reserves, revenue bond financing, and the State Revolving Fund (SRF) loan program. In order for the City to assure eligibility for the SRF program, concurrence must be obtained from MDEQ on environmental documents prepared and determinations issued by the City. The City would also likely qualify for the Renewable Resource Grant and Loan (RRGL) and Treasure State Endowment Program (TSEP) programs. Qualifying for the TSEP program would be contingent on the target rate requirements and requirements for the project to solve an urgent or serious health or safety problem or compliance with State or Federal regulations. It is unlikely the City would qualify for a Community Development Block Grant due to the low to moderate income requirements. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -12 Table ES-7. Capital Improvement Projects Schedule: Short-term (FY 19/20 to FY 23/24) Alternative Short-term Total Project Costs Project Classification FY 19/20 FY 20/21 FY 21/22 FY 22/23 FY 23/24 EQB 2: Construct new EQ Basin to be converted to a Primary Clarifier in the future $196,000 Engineering $2,349,000 Construction $2,545,000 Growth SCT 2: Convert Bioreactor to 5-stage System $118,000 Engineering $1,531,0001 Regulatory SCL 3: Install Dome Clarifier Covers $403,000 Engineering $3,199,000 Phase 1 Construction2 $1,621,000 Phase 2 Construction3 $5,223,000 Renewal & Replacement RAB 2: Reaeration Basin Modifications $32,000 Engineering $405,0004 Regulatory STK 5: Install Rotary Drum Thickeners $152,000 Engineering $1,813,000 Construction $1,965,000 Renewal & Replacement BDD 2: Composting Facility $631,000 Engineering $7,565,000 Construction $8,196,000 Renewal & Replacement, Growth Misc: Aeration Blower Evaluation Study $22,000 Engineering $22,000 Renewal & Replacement Misc: Biofilter Bed Rehabilitation $6,000 Engineering $70,000 Construction $67,000 Renewal & Replacement Misc: Chemical Room Modifications $29,000 Engineering $348,000 Construction $377,000 Renewal & Replacement, Growth Misc: Fermenter Condition Assessment $52,000 Engineering $52,000 Renewal & Replacement Misc: Effluent Management Plan $57,000 Engineering $57,000 Growth, Regulatory Misc: Effluent Temperature Mitigation Plan $60,000 Engineering $60,000 Regulatory Misc: Influent Piping & Diversion Structure Rehabilitation $50,000 Engineering $150,000 Construction $200,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs $248,000 $453,000 $82,000 $875,000 $150,000 Total Fiscal Year Construction Costs N/A $2,349,000 $3,349,000 $1,621,000 $9,796,000 Total Fiscal Year Costs $248,000 $2,802,000 $3,431,000 $2,496,000 $9,946,000 1. Construction cost = $1,413,000 in FY 24/25. See Table ES-8. 2. Cost for covering Secondary Clarifiers 1 and 2 3. Cost for covering Secondary Clarifier 3 4. Construction cost = $373,000 in FY 24/25. See Table ES-8. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES-13 Table ES-8. Capital Improvement Projects Schedule: Near-term (FY 24/25 to FY 33/34) Alternative Near-term Total Project Costs Project Classification FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 FY 31/32 FY 32/33 FY 33/34 INS 3: Two New Influent Screens $166,000 Engineering $1,991,000 Construction $2,157,000 Renewal & Replacement PCL 3: Convert Existing Primary Clarifiers to EQ; Two new 75–FT Circular Primary Clarifiers $624,000 Engineering $7,484,000 Construction $8,108,000 Growth SCT 2: Convert Bioreactor to 5-stage System $1,413,000 Construction $1,531,0001 Regulatory EFF 2: Tertiary Membrane Filtration $2,492,000 Engineering $29,900,000 Construction $32,392,000 Growth, Regulatory RAB 2: Reaeration Basin Modifications $373,000 Construction $405,0002 Regulatory AND 2: Anaerobic Digestion Equipment Replacement $112,000 Engineering $1,336,000 Construction $1,448,000 Renewal & Replacement AND 3: Add Second Primary Digester $553,000 $6,635,000 Construction $7,188,000 Renewal & Replacement Misc: Sidestream Treatment $194,000 Engineering $2,326,000 Construction $2,520,000 Growth, Regulatory Misc: Additional Standby Power $221,000 Engineering $2,644,000 Construction $2,865,000 Renewal & Replacement Misc: Digester Chemical Feed System $10,000 Engineering $111,000 Construction $121,000 Renewal & Replacement Misc: Replace Belt Filter Press $50,000 Engineering $590,000 Construction $640,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs $60,000 N/A N/A $278,000 $3,239,000 $624,000 $221,000 N/A N/A N/A Total Fiscal Year Construction Costs $1,786,000 $701,000 N/A N/A $3,327,000 $38,861,000 $7,484,000 $2,644,000 N/A N/A Total Fiscal Year Costs $1,846,000 $701,000 N/A $278,000 $6,566,000 $39,485,000 $7,705,000 $2,644,000 N/A N/A 1. Engineering cost = $118,000 in FY 23/24. See Table ES-7. 2. Engineering cost = $32,000 in FY 23/24. See Table ES-7. Kalispell AWWTP 2018 Facility Plan Update Executive Summary Page ES -14 Table ES-9. Capital Improvement Projects Schedule: Long-term (FY 34/35 to FY 38/39) Alternative Long-term Total Project Costs Project Classification FY 34/35 FY 35/36 FY 36/37 FY 37/38 FY 38/39 INP 2: Install Two New Influent Pumps $46,000 Engineering $548,000 Construction $594,000 Growth Misc: Administration/Laboratory Building $136,000 Engineering $1,626,000 Construction $1,762,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs N/A $46,000 N/A $136,000 N/A Total Fiscal Year Construction Costs N/A N/A $548,000 N/A $1,626,000 Total Fiscal Year Costs N/A $46,000 $548,000 $136,000 $1,626,000 CHAPTER 1 INTRODUCTION Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page i Contents 1 Introduction ....................................................................................................................................... 1-3 1.1 Previous Planning Efforts ....................................................................................................... 1-3 1.2 Facility Plan Update Objectives ............................................................................................. 1-3 1.3 Facility Plan Update Approach and Organization .................................................................. 1-4 1.4 MDEQ Circular DEQ-2 Facility Plan Requirements ............................................................... 1-4 1.5 Planning Area Description ...................................................................................................... 1-5 Figures Figure 1-1. Annexation Boundary for City of Kalispell ............................................................................... 1-6 Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page ii This page is intentionally left blank. Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page 1-3 1 Introduction This document provides an update to the wastewater treatment plant portions of the City of Kalispell Wastewater Facility Plan Update, completed in March 2008. The City has chosen to update the facility plan to identify equipment and treatment processes that are deficient or beyond their useful life, effectively plan for potential service area growth, and develop strategies to meet anticipated stringent nutrient limits. 1.1 Previous Planning Efforts The advanced wastewater treatment plant (AWWTP) was studied extensively during the early 2000’s when growth in the area was rapid and again more recently to meet regulatory requirements and study biosolids management alternatives. Previous studies include: • July 2002 City of Kalispell Water, Sewer and Storm Drainage Systems Facility Plan by HDR Engineering, Inc. (HDR) and Morrison Maierle, Inc. (MMI), also referred to as the 2002 Facility Plan. • March 2004 City of Kalispell Wastewater Facilities Plan by MMI/HDR/Stantec, also referred to as the 2004 PER. • 2005 Basis of Design Report by MMI/HDR • March 2008 Facility Plan Update by MMI/HDR • January 2016 Kalispell Temperature Monitoring Plan by HDR • August 2017 Kalispell AWWTP Facility Optimization Study by HDR • May 2018 Kalispell AWWTP Biosolids Management Plan by HDR 1.2 Facility Plan Update Objectives This plan’s recommendations are based on a detailed evaluation of feasible alternatives, with recommendations for improvements that are found to be the most cost-effective solutions to the City’s needs within a 20-year planning period. The primary objectives of this plan are to: • Update the facility flow and loading projections that correlate to more recent data provided by the City; • Evaluate each unit process for capacity and operational flexibility to show that adequate capacity exists to optimally treat the projected influent flows and loads throughout the planning period; and • Recommend process improvements needed to provide process unit redundancy, assure capacity is available for future wastewater flows, and the facility can meet future discharge permit limits. Implementation of recommended improvements is through a flexible plan that can be responsive to changing criteria and the City’s available resources. Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page 1-4 1.3 Facility Plan Update Approach and Organization This plan is focused on evaluating the City’s wastewater treatment plant. Recent condition and capacity assessments of the wastewater collection system are completed by the City in a separate facility plan update. Work efforts have relied upon the population and planning projections and facility performance data provided by the City. This facility plan update is comprised of an executive summary and six chapters which are described below. • Executive Summary o Summarizes the contents of each chapter below. • Chapter 1 – Introduction (this chapter) o Describes the motive for updating the facility plan and objectives and format of the facility plan update. • Chapter 2 – Effluent Limitations and Regulatory Requirements o Outlines the regulatory framework impacting the facility by describing the current effluent limitations the City is required to meet and anticipated water quality regulations. • Chapter 3 – Basis of Planning o Establishes the basis of planning, including flow and pollutant load projections, for a 20-year planning period through 2038. The projected values are used as the basis for developing proposed improvements. • Chapter 4 – Existing Wastewater Treatment Facility o Evaluates the existing capacity of treatment processes and facility equipment as compared to the projected flows and loads developed in Chapter 3. A brief description of each treatment plant process is also included in this chapter. • Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations o Evaluates potential AWWTP improvement alternatives for deficient areas of the facility identified in Chapter 4. Each alternative includes a description of the alternative, estimated cost, and evaluation criteria score. A recommended alternative is selected based on evaluation scoring. • Chapter 6 – Recommended Alternatives and Implementation Plan o Prioritizes recommended improvements and presents an implementation and financial summary plan. 1.4 MDEQ Circular DEQ-2 Facility Plan Requirements The regulatory document governing facility plans for wastewater treatment is Chapter 10 of Circular DEQ-2. The following main components of the plan are required: Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page 1-5 • Problem Evaluation and Existing Facility Review • Planning and Service Area • Population Projection and Planning Period • Hydraulic Capacity • Organic/Nutrient Capacity • Wastewater Treatment Facility Design Capacity • State and Federal Treatment Standards • Initial Alternative Development • Detailed Alternative Evaluation • Final Project Selection 1.5 Planning Area Description The planning and service area for the facility plan update matches the City’s adopted Annexation Boundary (Figure 1-1) as described in the Kalispell Growth Policy. The Evergreen service area is shown in relation to the planning and service area in the figure below. Kalispell AWWTP 2018 Facility Plan Update Chapter 1 - Introduction Page 1-6 Figure 1-1. Annexation Boundary for City of Kalispell CHAPTER 2 EFFLUENT LIMITATIONS AND REGULATORY REQUIREMENTS Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page i Contents 2 Effluent Limitations and Regulatory Requirements .......................................................................... 2-1 2.1 Introduction ............................................................................................................................. 2-1 2.2 MPDES Discharge Permit ...................................................................................................... 2-1 2.2.1 Effluent Limitations .................................................................................................... 2-2 2.2.2 Monitoring Requirements .......................................................................................... 2-2 2.2.3 Special Conditions ..................................................................................................... 2-3 2.2.4 Pretreatment Requirements ...................................................................................... 2-4 2.2.5 Compliance Schedule ............................................................................................... 2-5 2.3 Future Discharge Limitations ................................................................................................. 2-6 2.3.1 Numeric Nutrient Standards and General Variance Levels ...................................... 2-6 2.3.2 Ammonia Standards .................................................................................................. 2-9 2.3.3 Metals ........................................................................................................................ 2-9 2.3.4 Flathead Lake TMDL ................................................................................................. 2-9 2.4 Biosolids Regulatory Summary ............................................................................................ 2-13 2.4.1 Title 40 CFR, Part 503............................................................................................. 2-13 2.4.2 Regulatory Authorities ............................................................................................. 2-13 Tables Table 2-1. Outfall 001 Effluent Limitations ................................................................................................. 2-2 Table 2-2. Outfall 001 Self-Monitoring Requirements ................................................................................ 2-3 Table 2-3. Compliance Schedule ............................................................................................................... 2-5 Table 2-4. Narrative Approach from MDEQ 12B for Achieving Nutrient Limits ......................................... 2-7 Table 2-5. Anticipated General Variance Levels for Nutrients ................................................................... 2-8 Table 2-5. Ammonia Water Quality Standards, Current and EPA 2013 Update ....................................... 2-9 Table 2-6. Waterbody Segments for TMDLs Completed in 2014 ............................................................ 2-10 Figures Figure 2-1. Graphical Representation from MDEQ for Achieving Nutrient Limits ...................................... 2-8 Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page ii This page is intentionally left blank Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-1 2 Effluent Limitations and Regulatory Requirements 2.1 Introduction The City of Kalispell Advanced Wastewater Treatment Plant (AWWTP) is authorized by the Montana Department of Environmental Quality (MDEQ) to discharge treated effluent to Ashley Creek. This chapter describes the current effluent limitations the City is required to meet and discusses anticipated water quality regulations. Future regulations impact areas of focus when evaluating the facility and selection of recommended alternatives for some treatment processes. Although future water quality regulatory impacts are somewhat unknown, the City should continue to pay close attention to permitting trends and environmental regulations both nationally and in Montana. 2.2 MPDES Discharge Permit The current Montana Pollutant Discharge Elimination System (MPDES) permit issued for the Kalispell AWWTP, Permit No. MT 0021938, became effective on August 1, 2015 and will expire on July 31, 2020. The City is permitted to discharge from a single outfall, Outfall 001, which is located at 48.17442 N latitude and 114.30851 W longitude. The permit contains the main sections listed below. Each section is described further in the next section. • Effluent Limitations o Presents water quality parameters that must be achieved in the facility effluent. • Monitoring Requirements o Lists sample location, frequency, and type of measurement for various wastewater constituents. • Special Conditions o Supplement effluent limitations. Special conditions include additional monitoring and special studies, best management practices (BMPs), and/or compliance schedules. • Pretreatment Program o Describes the requirements of the City to monitor industrial discharge for compliance with the national Pretreatment Standards established by the United States Environmental Protection Agency (US EPA). • Compliance Schedule o Lists dates for actions or deliverables that must be completed by the permittee. Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-2 2.2.1 Effluent Limitations During the term of the permit, discharge from Outfall 001 shall, at a minimum, meet the effluent limits presented in Table 2-1. Additionally, there shall be no discharge of floating solids or visible foam in other than trace amounts. There shall be no discharge which causes visible oil sheen in the receiving stream [ARM 17.30.637(1)(b)]. Table 2-1. Outfall 001 Effluent Limitations Parameter Units Average Monthly Limit 1 Average Weekly Limit 1 Maximum Daily Limit 1 BOD5 mg/L 10 15 -- lb/day 259 388 -- TSS mg/L 10 15 -- lb/day 259 388 -- E. coli Bacteria 2,3 cfu/100 mL 126 252 -- E. coli Bacteria 3,4 cfu/100 mL 630 1,260 -- Total Nitrogen 5 lb/day 397 -- -- Total Phosphorus as P 6 lb/day 9.9 -- -- Total Phosphorous as P 7 lb/day 25.8 -- -- Oil and Grease mg/L -- -- 10 Dissolved Oxygen Saturation Percent -- -- >75% 1. See Definition section at end of permit for explanation of terms. 2. This limit applies during the period April 1 through October 31, annually. 3. Report Geometric Mean if more than one sample is collected during reporting period. 4. This limit applies during the period November 1 through March 31, annually. 5. Calculated as the sum of Total Kjeldahl Nitrogen (TKN) and nitrate/nitrite as N concentrations. 6. This limit applies during the period July 1 through September 30, annually. 7. This limit applies during the period October 1 through June 30, annually. 2.2.2 Monitoring Requirements Samples shall be collected, preserved and analyzed in accordance with approved procedures listed in 40 CFR 136 and the analysis must meet any Required Reporting Values (RRVs) listed in MDEQ Circular DEQ-7, unless otherwise specified. Monitoring location for influent is upstream of influent screening, prior to the influent Parshall flume. Monitoring location for effluent is the final effluent channel within the Control Building. Monitoring of the effluent must be representative of the volume and nature of the discharge. Effluent and influent monitoring requirements are presented in Table 2-1. Dissolved oxygen monitoring will be conducted at the reaeration basin prior to discharge to discharge. Influent and effluent monitoring results must be reported within a Discharge Monitoring Report (DMR). Monitoring results must be submitted electronically (NetDMR web-based application) no later than the 28th day of the month following the end of the monitoring period. If no discharge into Ashley Creek is observed during the reporting period, “no discharge” shall be reported on the Net DMRs. Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-3 Table 2-2. Outfall 001 Self-Monitoring Requirements Parameter Units Sample Location Sample Frequency Sample Type1 Flow mgd Effluent Continuous (2) Biochemical Oxygen Demand (BOD5) mg/L Influent 5/Week Composite mg/L Effluent 5/Week Composite % Removal3 NA 1/Month Calculated lb/day Effluent 1/Month Calculated Total Suspended Solids (TSS) mg/L Influent 5/Week Composite mg/L Effluent 5/Week Composite % Removal3 NA 1/Month Calculated lb/day Effluent 1/Month Calculated pH s.u. Effluent Daily Instantaneous Temperature ºC Effluent Daily Instantaneous Dissolved Oxygen Saturation Percent Effluent Daily Grab E. coli Bacteria 4 cfu/100 mL Effluent 5/Week Grab Total Ammonia as N mg/L Effluent 1/Month Composite Nitrate + Nitrite as N mg/L Effluent 1/Week Composite Total Kjeldahl Nitrogen as N mg/L Effluent 1/Week Composite Total Nitrogen5 mg/L Effluent 1/Week Calculated lb/day NA 1/Month Calculated Total Phosphorus as P mg/L Effluent 1/Week Composite lb/day NA 1/Month Calculated Oil and Grease6 mg/L Effluent 1/Quarter Grab Copper, total recoverable µg/L Effluent 1/Quarter Composite Whole Effluent Toxicity, Chronic3 % Effluent Effluent 2/Year Composite Footnotes: 1. See Definition section at end of permit for explanation of terms. 2. Requires recording device or totalizer; permittee shall report daily maximum and daily average flow on DMR 3. See narrative discussion in this section of permit for additional details. 4. Report geometric mean 5. Calculated as the sum of Nitrate + Nitrite as N and Total Kjeldahl Nitrogen (TKN) concentrations. 6. Collect a sample and analyze using EPA Method 1664, Revision A: N-Hexane Extractable Material (HEM), or equivalent, either once per quarter or when an oil sheen is observed. 2.2.3 Special Conditions The City’s MPDES permit has several special conditions that serve as supplemental items to the effluent limitations. Sludge Disposal The use and disposal of sewage sludge must be in conformance with 40 CFR 503. Biosolids Laws and Regulations are governed by the US EPA. This document Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-4 establishes general requirements, pollutant limits, management practices, and operational standards for final use and disposal of sewage sludge generated from wastewater treatment facilities. A summary of the 503 regulations is provided in Section 2.4 below. Effluent Toxicity In cases where effluent toxicity is detected in the required resample, a Toxicity Identification Evaluation and Toxicity Reduction Evaluation (TIE-TRE) must be initiated. This evaluation establishes the cause, location, and response to the toxicity. A TRE plan must be submitted to DEQ within 45 days after confirmation of toxicity. Instream and Effluent Temperature Monitoring The MPDES permit requires monitoring the temperature impact of the Kalispell AWWTP effluent on Ashley Creek by collecting temperature and flow measurements of the effluent and Ashley Creek. Measurement devices were placed upstream of the treatment plant outfall and downstream of the mixing zone. The City is required to collect continuous flow and temperature data of the effluent prior to discharge. Data collected is saved digitally and submitted on a yearly basis to MT-eWQX. This monitoring started during the summer of 2016 and will be completed on September 30, 2019. 2.2.4 Pretreatment Requirements Implementation of pretreatment requirements state the City is the primary party responsible for enforcing against discharges prohibited by 40 CFR 403.5 and Pretreatment Standards set by US EPA in accordance with Section 307 (b) and (c). Operations of the AWWTP are required to operate in accordance with 40 CFR Part 403. The requirements include identifying character and volume of pollutants from industrial facilities discharging to the AWWTP, updating information yearly, reviewing permits, and updating records. All Significant Industrial User (SIU) are to be monitored, regulated, permitted, and aided by City staff in operation, testing, and implementation of required pretreatment. The City prohibits the introduction of damage causing or treatment prohibiting pollutants into the treatment system. Establishment, enforcement, and continued development of limitations found in 40 CFR 403.5 (a) and (b) is required by the City. Technical evaluation of local limitations need to be revised within 12 months of the effective date of the permit, in accordance with EPA’s “Local Limits Development Guidance” July 2014. All proposed limits will be submitted to the Approval Authority in the 40 CFR 403.18 specified format. Influent and effluent are tested for pollutants listed in 40 CFR Part 122 Appendix D. Table II pollutants require testing at least once per year, while pollutants in Table III require four or more tests per year. Submission of suspected or known compounds from Table V is required with yearly pretreatment report. Biosolids are tested yearly for pollutants in Table III of 40 CFR Part 122. If Table II or Table V pollutants were found in the influent within the past two years or the last two analyses, whichever is greater, the biosolids must be analyzed for these pollutants. Sample collection and analysis will follow 40 CFR Part 503 or EPA Region 8 General Permit guidelines. Biosolids pollutants will be reported in the pretreatment annual report. All testing will follow procedures Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-5 established in 40 CFR Part 136 or best professional judgment/State guidance/Approval Authority, detection limits must be stated when reporting non-conforming tests. Annual reports will provide a review of SIUs over the past 12 months who have significantly violated Pretreatment Standards or requirements. This list is to be published in a newspaper of general circulation in the Kalispell area. The pretreatment program annual reports are submitted on or before March 28th to the Approval Authority and state permitting authority containing EPA requested information. The annual report contains a list of all SIUs with Standard Industrial Classification codes, permit status, and a summary of monitoring activities performed that year. For non-complying SIUs a summary of the violation(s), actions taken, and outcome will be documented. If any discharge rights were terminated or revoked during the year, reasons will be stated. If unforeseen discharges to the system were accepted, information will be shared with the Approval Authority. Updates to the pretreatment program and evaluation of pollutant loading against approved Maximum Allowable Headworks Loadings will be reported annually. The City is required to notify the MDEQ and the Approval Authority of any introduction by new or existing industrial users, or substantial change in pollutants within 60 days of the introduction. This notice must identify new pollutants, substantial changes in volume or character of pollutants, identity of the industrial user, nature and concentration of pollutants, average and maximum flow of discharge, and anticipated impact of the discharge. In cases of noncompliance, the EPA may issue a notice that enforcement action must be taken against an industrial user. Action must be taken within 30 days of this notice. The state permitting authority and/or the EPA retains the right to take legal action against industrial contributors for violations of a permit. In cases where failure to properly develop and enforce Pretreatment Standards and requirements, the City will be held accountable and legal action may be taken. 2.2.5 Compliance Schedule A compliance schedule that requires completion of a facility optimization study is included in the current permit (Table 2-3). The facility optimization study was completed and submitted to MDEQ in August 2017. Table 2-3. Compliance Schedule Action Frequency Scheduled Completion Date of Action 1 Report Due Date 2 Complete a Facility Optimization Study and Nutrient Reduction Analysis Single Event By July 31, 2017 NA Submit Notification that the Facility Optimization Study and Nutrient Reduction Analysis is Complete Single Event By July 31, 2017 August 28, 2017 Footnotes: NA = Not Applicable 1. The actions must be completed on or before the scheduled completion dates. 2. This notification must be received by the Department on or before the scheduled due date. Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-6 2.3 Future Discharge Limitations 2.3.1 Numeric Nutrient Standards and General Variance Levels In July 2014 the Montana Board of Environmental Review adopted base numeric nutrient standards, defined as “numeric water quality criteria for nutrients in surface water that are adopted to protect the designated uses of a surface water body. The term does not include numeric water quality standards for nitrate, nitrate plus nitrite, or nitrite that are adopted to protect human health.” The standards were published by the MDEQ in Department Circular DEQ-12A. The AWWTP discharge is located in Ecoregion Level III Northern Rockies (15). This designation sets the numeric nutrient standards at: • Average Monthly Total Nitrogen Limit = 0.275 mg/L • Average Monthly Total Phosphorus Limit = 0.025 mg/L The limits stated above are effective from July 1st through September 30th. The City applied for a general variance from the stringent limits. The general variance from the stringent limits expires in 2034. Under the current permit cycle, the variance requirements for the City are: • Facility discharge of 1 MGD or greater, • Monthly average treatment requirements of 1.0 mg/L and 10.0 mg/L for Total Phosphorus and Total Nitrogen respectively, and • A Facility Optimization Study and Nutrient Reduction Analysis must be completed. As mentioned previously, this study has been completed. Basic numeric nutrient standards and general variance requirements are reviewed every three years by the MDEQ. There are three possible outcomes: extend without modification, modify and extend, or allow to expire. During the 2017 triennial review the EPA established a requirement for a Highest Attainable Condition (HAC) for Montana municipalities. The HAC is a quantifiable expression of the best condition that can be achieved during the term of the variance. Half of the municipalities in Montana must be able to afford the level of treatment in order for it to be considered a HAC. The HAC adopted in 2017 for wastewater treatment facilities in Montana with flow greater than 1 MGD requires an effluent total nitrogen concentration of 6.0 mg/L and effluent total phosphorus concentration of 0.3 mg/L. MDEQ Circular DEQ-12B was revised in June 2017 to include steps and approximate timelines to achieve TN = 6.0 mg/L and TP = 0.3 mg/L. The narrative timeline is reproduced in Table 2-4 and illustrated graphically in Figure 2-1. The next triennial review will occur in 2020 and the general variance levels are expected to decrease even further. Based on previous meetings and discussions with regulators the best postulation for future nutrient limits facing the City, where treatment facility flow is greater than 1 MGD, is included in Table 2-5 for years of anticipated permit renewals. Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-7 Table 2-4. Narrative Approach from MDEQ 12B for Achieving Nutrient Limits Description of Step Approximate Time to Complete Step (years) 1. Implementation of advanced operational strategies to reduce nutrients using existing infrastructure. Evaluate effects of operational changes and fine tune as necessary. Operations staff identify potential minor capital improvements, if any, that could be made to further advance operational strategies. Preliminarily assess the feasibility of trading, reuse, etc. 2 2. If Table 12B-1 treatment requirements are not achieved, hire an engineer to prepare a preliminary engineering report (PER) that evaluates options for minor and/or major facility improvements, trading or reuse that lead to further nutrient reductions that build upon developed operational strategies, if appropriate. Continue to fine-tune operational strategies. Begin discussion with funding agencies and submit PERs to those agencies, if necessary (for major upgrades). 1 3. Go through funding agency timelines and requirements for planning, if necessary. This may involve legislative approval, depending upon the funding sought. Implement minor facility improvements, if appropriate, and fine tune operations for further TN and TP reductions. 2 4. Design major capital improvements. Go through the Department (DEQ) and other funding agency review and approval processes for the design/bidding phase, including MEPA analysis, adjustments of rates and charges, legal opinions, etc. Bid major capital project. 2 5. Construct major capital project, including trading and/or reuse, if appropriate. Begin operating new infrastructure and fine tuning operations. Continue with advanced operational training with new infrastructure. Evaluate nutrient reductions achieved with major capital project and operator optimization. 4 6. If Table 12B-1 treatment requirements are still not achieved, hire engineer to evaluate alternatives in a PER for next steps to meet Table 12B-1 treatment requirements for TN and TP. 1 7. Submit PER to funding agencies for review, approval, MEPA, etc. Legislative approval required? Obtain funding. 2 8. Design and bid capital project to meet Table 12B-1 treatment requirements for TN and TP. 1 9. Construct capital upgrades, including trading, reuse, etc., if appropriate. Continue with operational optimization to meet Table 12B-1 treatment requirements. 2 Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-8 Figure 2-1. Graphical Representation from MDEQ for Achieving Nutrient Limits Table 2-5. Anticipated General Variance Levels for Nutrients Permit Renewal Year General Variance Level TN (mg/L) TP (mg/L) 2020 6.0 0.3 2025 4.0 0.07 2030 3.0 0.05 20351 0.275 0.025 1. General variance expires in 2034 and numeric nutrient standards must be met. Another variance pathway defined in Circular DEQ-12B allows for site specific criteria to be developed through sampling and modeling of the receiving water. This method aims to determine the direct impacts on algae grown under different scenarios of facility effluent flow and water quality. The City is currently planning to conduct sampling and modeling in Ashley Creek as part of an alternative strategy to address future regulations. The City has been an active participant in regulatory discussions, including Nutrient Workgroup Meetings, regarding the establishment of nutrient limits. Being an active voice Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-9 in the regulation setting process ensures the most beneficial outcome possible for City of Kalispell citizens. A continued proactive approach is recommended. 2.3.2 Ammonia Standards The permit calculations show no reasonable potential to exceed the ammonia standards at this time so the facility does not have an ammonia limit. However, ammonia standards for freshwater mussels have been set by the US EPA (Table 2-5). The standards have not been adopted by MDEQ yet, but it is anticipated they will be adopted by MDEQ during the 2020 triennial review. The incorporation of federal ammonia standards could result in an effluent limit for the City in the next permit cycle. Table 2-6. Ammonia Water Quality Standards, Current and EPA 2013 Update Ammonia Standards Acute (mg/L) Chronic (mg/L) Current1 3.83 1.64 EPA 20131 3.832 0.783 Footnotes: 1. Values were calculated using a pH of 8.2 s.u. and a Temperature of 15.2°C. 2. From Table 5a of EPA’s Aquatic Life Ambient Water Quality Criteria for Ammonia – Freshwater – 2013. 3. From Table 6 of EPA’s Aquatic Life Ambient Water Quality Criteria for Ammonia – Freshwater – 2013. 2.3.3 Metals Ashley Creek is not listed as being impaired for metals. The calculations by MDEQ in the most recent permit fact sheet found no reasonable potential to exceed standards for metals or cyanide. Effluent monitoring for copper continues but monitoring for all other metals was discontinued in the current permit. 2.3.4 Flathead Lake TMDL A total maximum daily load (TMDL) is the maximum amount of a pollutant that a body of water, e.g., river, stream, or lake, can receive and still beneficially support agricultural, industrial, and recreational activities. A TMDL is established on a watershed basis and can be issued for nutrients, temperature, or sediments depending on the waters within the watershed/basins impairment listing. The MDEQ is responsible for completing TMDLs in Montana. Phase One A nutrient TMDL was established for Flathead Lake with the Nutrient Management Plan and Total Maximum Daily Load for Flathead Lake, Montana. The document was prepared and published by MDEQ on December 28, 2001 and approved by Region 8 of the US EPA on March 31, 2002. Although the Nutrient Management Plan shows Sewer Treatment Plants (STPs) at 2% and 1% of the Phosphorus and Nitrate/Nitrite load, respectively, a 15% reduction in man-caused nitrogen and phosphorus loads, plus a 10% margin of safety was proposed. The 10% margin of safety was included to account for projected future increases in point source loads attributable to increased wastewater flows and continuing upward trend in population growth in the unincorporated areas of Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-10 the basin. The document specifically establishes a Phase 1 reduction target of 25% for the area north of Flathead Lake, including the communities of Kalispell, Whitefish, Columbia Falls, Bigfork, Evergreen, Somers and Creston. The document states, “It is not envisioned that achieving a 25% load reduction from this single area will result in achieving the overall 15% basin wide load reduction. Rather, this is an interim load reduction goal for an area known to be an immediate threat to Flathead Lake (i.e., an area known to deliver relatively high nutrient load for which the technology exists to achieve load reductions). This source area will be further evaluated in context with all other potential significant sources in Phase 2. A revised allocation plan for this area, and all other areas of the basin, will be determined based on the results of Phase 2.” Work associated with Phase 2 of the TMDL is currently underway and a schedule for completion is unknown. Interim TMDL Work MDEQ and US EPA were under a court order to complete the TMDLs for the areas listed in Table 2-6 before the end of calendar year 2014. Completion of Phase 2 of the Flathead Lake nutrient TMDLs was not a requirement of the court order. The Flathead – Stillwater Planning Area Nutrient, Sediment, and Temperature TMDLs and Water Quality Improvement Plan was prepared and published by MDEQ in October 2014 and approved by Region 8 of the US EPA in December 2014. Table 2-7. Waterbody Segments for TMDLs Completed in 2014 Waterbody & Location Description Upper Ashley Creek Ashley Lake to Smith Lake Middle Ashley Creek Smith Lake to Kalispell Airport Road Lower Ashley Creek Kalispell Airport Road to mouth (Flathead River) Spring Creek Headwaters to mouth (Ashley Creek) The nutrient waste load allocations (WLAs) established for the Kalispell AWWTP on the lower segment of Ashley Creek were based on meeting end of pipe numeric nutrient criteria (TN = 0.275 mg/L, TP = 0.025 mg/L) during the summer months (July 1st through September 30th). An estimated 95% reduction in TN and 70% reduction in TP would be required to meet WLAs developed. The pathway to such large reductions in nutrient levels is described in the variance process discussed in Section 2.3.1. Many uncertainties exist with the model used for developing the allocations presented in the 2014 TMDL document. In particular, the Smith Lake and upstream wetland systems are significant sources of nutrient loading to Ashley Creek. The mechanisms of this nutrient loading are not fully understood and additional investigation is needed to determine the exact source. Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-11 The sediment WLA for the AWWTP is expected to be met by adhering to discharge permit limits. Sediment loads presented in the 2014 document are not intended to be incorporated into permit limits or added to permit conditions. The lower segment of Ashley Creek was determined to be impaired for temperature. From Section 7.5.4 of the 2014 document: “Per Montana state rule (ARM 17.30.637(2)), no wastes may be discharged such that the wastes, either alone or in combination with other wastes, will violate, or can reasonably be expected to violate, any of the standards. With reference to temperature this means that for WWTPs and other permitted dischargers, the discharge concentration must not change the water temperature more than allowed by the water quality standard.” Therefore, a temperature TMDL was developed for the lower Ashley Creek segment. Implementation of best management practices is anticipated for meeting temperature WLAs for the AWWTP. However, a phased approach to possible implementation is outlined in the 2014 document: 1. 2015 – 2020 MPDES Permit (current permit) a. STEP 1 i. The City of Kalispell will collect additional data (3-5 years) to address the impacts of the Kalispell WWTP on Ashley Creek ii. Place a temperature logger and a trutrack upstream of the WWTP and downstream of the WWTP below the mixing zone (defined by DEQ in consultation with the City of Kalispell), from July 1 – September 30 each year. iii. Collect a flow measurement at the trutrack locations on the same day every other week using protocols approved by DEQ. iv. Collect real-time (continuous) discharge and temperature data from the WWTP effluent before it enters Ashley Creek at a location approved by DEQ. 2. Second permit cycle (5 years) a. STEP 2 (First 2 years of the permit cycle) i. MDEQ will analyze data ii. Determine when the WWTP is causing the water quality standard for temperature to be exceeded and the magnitude and duration of any exceedances. iii. Determine the effluent temperature (target) at which exceedances are eliminated or reduced to an acceptable level. b. STEP 3 (Final 3 years of the permit cycle) i. If warranted, per the results of STEP 2, the City of Kalispell will study the feasibility of achieving the target Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-12 ii. Identify and analyze the techniques available for achieving the temperature target in WWTP effluent. iii. Cost/benefit analysis of each technique. iv. Identify and analyze alternatives for reducing temperature in Ashley Creek (e.g., increasing instream flow upstream of the AWWTP). 3. Third permit cycle (5 years): a. STEP 4 – If warranted, per the results of STEP 3 i. the City of Kalispell will determine and outline an implementation plan deemed sensible by DEQ and put it in document format ii. Using the information in STEPs 1 – 4 determine what sensible actions will be pursued by the Kalispell WWTP. iii. Document: 1. The actions that will be taken by the WWTP to improve water temperature in Ashley Creek downstream of the discharge to the extent it is affected by the discharge, 2. A timeline for implementation, and 3. Monitoring that will occur. 4. Fourth permit cycle (5 years): a. STEP 5 – If warranted, per the results of STEP 4 i. The City of Kalispell will implement the plan ii. Follow through with the plan as documented in STEP 4. iii. Achieve the final effluent limits. As mentioned in Section 2.2.3, the required monitoring in Ashley Creek started during the summer of 2016 and will be completed on September 30, 2019. Phase Two Phase 2 of the Flathead Lake TMDL is still ongoing, which may require additional nutrient load reductions in Ashley Creek to meet annual load limits. The 2014 TMDL plan states the following: “If needed, nutrient TMDLs for Ashley Creek and Spring Creek will either be revised in the future to incorporate the findings of the Phase 2 Flathead Lake nutrient TMDLs or a new layer of allocations may instead be applied to address the annual loading since the existing allocations to the Ashley Creek watershed only apply during the algae growing season. In addition to Ashley Creek and Spring Creek, Flathead Lake Phase 2 TMDL allocations would also be applied to other tributaries throughout the Flathead Lake watershed. There are several approaches that could be used for setting these allocations. This could include allocations to multiple pollutant sources within a specific tributary, or application of load reductions to specific pollutant source Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-13 types across multiple tributaries. Note that tributary allocations can be developed for a downstream lake’s TMDL without writing a TMDL specific to each tributary.” The Phase 2 Flathead Lake TMDL plan and tributary TMDLs have the potential to place more restrictive conditions on the City of Kalispell AWWTP discharge in the future. This is a concern on Ashley Creek because it is a relatively small waterbody and in-stream water quality conditions may be impacted by other activities in the watershed. Effluent dilution in Ashley Creek is limited and the wastewater treatment plant discharge represents a significant portion of the total stream flow. In accordance with Montana Code Annotated MCA 75-5-703, which reads, “When a source implements voluntary measures to reduce pollutants prior to development of a TMDL, those measures, whether or not reflected in subsequently issued waste discharge permits, must be recognized in development of the TMDL in a way that gives credit for the pollution reduction efforts,” these voluntary efforts should be taken into consideration in the formulation of the Flathead Lake TMDL. City staff have taken an active role by meeting with MDEQ to discuss the Flathead Lake TMDL and have participated in Phase 2 advisory groups. The City of Kalispell will continue to do their part to protect water quality in the Flathead Basin. 2.4 Biosolids Regulatory Summary The City continually generates biosolids as part of the treatment systems at the AWWTP. Biosolids use and disposal is regulated by 40 CFR, Part 503. Biosolids regulations were detailed in the 2018 Biosolids Management Plan and are briefly summarized in the section below. 2.4.1 Title 40 CFR, Part 503 In response to the Clean Water Act Amendments of 1987, the EPA published Title 40 of the Code of Federal Regulations (CFR), Part 503 Standards for the Use or Disposal of Sewage Sludge on February 19, 1993. The sewage sludge/biosolids standards, commonly referred to as Part 503 Rule or Part 503, became effective on March 22, 1993.The Part 503 Rule is a complex, risk based assessment of potential environmental effects of pollutants that may be present in biosolids. The EPA subsequently published A Plain English Guide to the EPA Part 503 Biosolids Rule in September 1994 to help end users interpret and implement the rule. The Part 503 Rule regulates pollutant and pathogen concentrations as well as vector attraction reduction (VAR). The guideline defines biosolids as Class A or Class B, depending on the potential level of pathogens. Class A biosolids must meet strict pathogen standards and can be used with no restrictions, while Class B biosolids can meet less stringent pathogen requirements, with application restricted to crops with limited human and animal exposure. Biosolids in both classes must meet VAR requirements. 2.4.2 Regulatory Authorities There is currently no EPA Region 8 Biosolids Coordinator according to the EPA website https://www.epa.gov/biosolids/forms/contact-us-about-biosolids. The EPA consolidated Kalispell AWWTP 2018 Facility Plan Update Chapter 2 – Effluent Limitations and Regulatory Requirements Page 2-14 all biosolids to Region 10. The biosolids state coordinators for Montana are Tom Reid and Rick Thompson of the MDEQ. CHAPTER 3 BASIS OF PLANNING Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page i Contents 3 Basis of Planning .............................................................................................................................. 3-1 3.1 Introduction ............................................................................................................................. 3-1 3.1.1 Concurrent Work ....................................................................................................... 3-1 3.2 Historical Wastewater Flows and Loads ................................................................................ 3-1 3.2.1 Evaluation Parameters .............................................................................................. 3-1 3.2.2 Wastewater Sources ................................................................................................. 3-2 3.2.3 AWWTP Influent Flows ............................................................................................. 3-2 3.2.4 AWWTP Influent Wastewater Characterization ........................................................ 3-4 3.2.5 Per Capita Wastewater Demands ............................................................................. 3-7 3.3 Population Projections and Planning Period .......................................................................... 3-9 3.4 Projected Wastewater Flow and Loads .................................................................................. 3-9 3.5 Environmental Factors ......................................................................................................... 3-12 Tables Table 3-1. AWWTP Influent Flow Data1 ..................................................................................................... 3-3 Table 3-2. Peak Hour Flow and Peaking Factors ...................................................................................... 3-3 Table 3-3. Typical Municipal Wastewater Concentrations ......................................................................... 3-4 Table 3-4. Typical Municipal Wastewater Concentrations ......................................................................... 3-4 Table 3-5. Combined Influent Wastewater Characterization1 .................................................................... 3-6 Table 3-6. Influent BOD and COD Characterization .................................................................................. 3-6 Table 3-7. Evergreen Only Wastewater Characterization ......................................................................... 3-7 Table 3-8. Per Capita Wastewater Flow Demands .................................................................................... 3-8 Table 3-9. Per Capita Wastewater Load Values ........................................................................................ 3-9 Table 3-10. Typical BOD and TSS per Capita Loads for Domestic Wastewater ....................................... 3-9 Table 3-11. Projected Service Populations .............................................................................................. 3-10 Table 3-12. Projected Influent Flows and Loads...................................................................................... 3-11 Figures Figure 3-1. Log-Normal Distribution of TKN mg/L Data ............................................................................. 3-5 Figure 3-2. Log-Normal Distribution of TKN lb/d Data ............................................................................... 3-5 Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page ii This page is intentionally left blank. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-1 3 Basis of Planning 3.1 Introduction An evaluation of the influent wastewater flows and wasteloads to the Kalispell AWWTP was conducted to establish a planning basis for development of future improvements at the facility. The flows and wasteloads are based on the existing environment, the population and land use in the service area, and infiltration and inflow to the collection system. Historical AWWTP data and population projections were provided by the City of Kalispell and were used to establish wastewater influent flow per-capita values and projections for flow and loading for 5-day biochemical oxygen demand (BOD5), total suspended solids (TSS), volatile suspended solids (VSS), total Kjeldahl nitrogen (TKN), ammonia (NH4-N), and total phosphorous (TP) for the years 2018, 2023, 2028, 2033, and 2038. The projected values will be used as the planning basis for proposed improvements developed as part of the facilities planning effort. This chapter presents historical and future flows, associated wasteloads, and describes the methodology used to determine the projected values. 3.1.1 Concurrent Work The City is currently updating the facility plan for the sewer collection system as part of a separate work effort. Findings of a wastewater characterization analysis were sent to HDR for review and incorporation into this chapter of the AWWTP Facility Plan Update. Current and projected AWWTP influent flows and planning area populations were discussed with the authors of the collection system facility plan and are described below. 3.2 Historical Wastewater Flows and Loads 3.2.1 Evaluation Parameters In order to evaluate the adequacy of the existing wastewater facilities to serve a future population and appropriately size and select process equipment for wastewater treatment facilities, characteristics of the wastewater, such as volumetric flow, organic strength, suspended solids content, and nutrient loading must be evaluated. Design parameters are dictated by discharge permit requirements and local regulatory authority design requirements. The following design flows must be identified and used for design of wastewater treatment plants as required by MDEQ Circular DEQ-2, Section 11.241: • Average Flow • Maximum Month Flow • Maximum Day Flow • Peak Hour Flow • Peak Instantaneous Flow Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-2 BOD5, TSS, phosphorus, and nitrogen concentrations are also important wastewater characteristics that must be evaluated in a wastewater facility plan. The BOD5 measures the dissolved oxygen consumed in degrading organic matter, and is an indirect measure of the organic strength of the wastewater. TSS is a measure of particulate matter in the wastewater. Phosphorus and nitrogen are nutrients that can encourage unwanted algal growth in the receiving water. Phosphorous is found in wastewater both as organic and inorganic phosphate. Nitrogen is present in both unoxidized (TKN, including ammonia and organic nitrogen), and oxidized forms (nitrates and nitrites). 3.2.2 Wastewater Sources In addition to receiving wastewater from City of Kalispell customers, the AWWTP also receives wastewater from the Evergreen Water and Sewer District No. 1 (the District). The District entered into an Interlocal Agreement with the City to convey raw wastewater that shall not exceed 0.805 million gallons average daily flow to the Kalispell AWWTP. It should also be noted that the City of Kalispell has little industry and therefore there is a minimal amount of industrial load to the AWWTP. However, a pretreatment program is required by permit and the City monitors industrial discharges according to national standards. The pretreatment program is described in Chapter 2. A meat packing facility discharges into the collection system close to the AWWTP, but previous analysis has indicated this low flow, high concentration wastewater has minimal impact on influent wasteload compared to the residential load. Similarly, City staff indicate the AWWTP receives wastewater from craft breweries within City limits. 3.2.3 AWWTP Influent Flows Historical influent wastewater flow data was analyzed to evaluate trends in flow to the Kalispell AWWTP. Table 3-1 provides a summary of AWWTP influent flow data for the period from 2012 through 2017. MDEQ Circular DEQ-2 defines maximum month flow as the average daily flow received during the maximum calendar month or 30 consecutive days, whichever is greater. An analysis of the flow data revealed a 30-day moving average method resulted in greater values than the calendar months for the period of review. Therefore, the maximum month values presented here are slightly greater than the values presented in the Sewer Collection System Facility Plan. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-3 Table 3-1. AWWTP Influent Flow Data1 Year Min Day (MGD) Ave Day (MGD) Max Month (MGD) Max Day (MGD) 2012 2.08 2.73 3.852 5.02 2013 1.91 2.46 2.883 4.42 2014 2.04 2.72 3.774 8.51 2015 1.95 2.60 3.765 5.78 2016 2.06 2.64 2.986 4.49 2017 2.18 2.97 5.367 8.66 Average 2.04 2.69 3.778 6.15 1 Influent flows from Kalispell and Evergreen service areas. 2 30-day period ending 7/4/2012 3 30-day period ending 6/14/2013 4 30-day period ending 7/11/2014 5 30-day period ending 3/7/2015 6 30-day period ending 11/7/2016 7 30-day period ending 4/8/2017 8 Average for the same time period in the Sewer Collection System Facility Plan is 3.67 MGD Hourly AWWTP influent flow data for select time periods of 2017 were analyzed for the Sewer Collection System Facility Plan. The sample periods were selected based on either a dry weather period (no measurable precipitation) or wet weather period (approximately one inch of rain). The peak hour flow data and resulting peaking factors are reproduced and summarized in Table 3-2. A peak hour flow peaking factor of 3.3 was calculated for current conditions. Based on available data and recording equipment measurement frequency, the peak instantaneous flow is assumed to be the same as peak hour flow of 10.0 MGD, which occurred on March 15, 2017 at 12:00 AM. Table 3-2. Peak Hour Flow and Peaking Factors Wet Weather Dry Weather 3/15/2017 4/26/2017 6/13/2017 9/16/2017 Peak Hour Flow (MGD) 10.0 5.2 4.8 3.5 Peaking Factor 3.3 1.7 1.6 1.2 The City should remain cognizant of high influent AWWTP flows and make a concerted effort to reduce infiltration and inflow (I/I) in the collection system to mitigate adverse impacts to treatment processes at the AWWTP. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-4 3.2.4 AWWTP Influent Wastewater Characterization Historical influent water quality data from 2012 through 2017 were analyzed to evaluate trends in wasteloads to the Kalispell AWWTP. Table 3-3 and Table 3-4 present typical influent wastewater concentrations. These values can vary depending on site specific environmental conditions, solids handling methods at the treatment facility, and system contributors. However, they are presented here for comparison purposes and are utilized to identify any potential erroneous data outliers within the Kalispell AWWTP data. Table 3-3. Typical Municipal Wastewater Concentrations Parameter Concentration (mg/L) Typical Range1 Typical Design Value1 BOD5 110-350 190 TSS 120-400 210 TKN 20-70 40 TP 4-12 7 1 Reference: Metcalf and Eddy, Inc., Wastewater Engineering Treatment and Reuse, Fourth Edition, 2003. Table 3-4. Typical Municipal Wastewater Concentrations Parameter Concentration (mg/L) Soluble Particulate Total VSS 190 Inert SS 50 TSS 240 BOD5 65 135 200 COD 130 260 400 TN 20 10 30 TP 5 2 7 1 Reference: Design of Municipal Wastewater Treatment Plants, WEF Manual of Practice 8, Fourth Edition, ASCE Manuals and Reports on Engineering Practice No. 76, Volume 1, 1998. Kalispell AWWTP data from 2012 through 2017 were evaluated for influent BOD5, TSS, TKN, ammonia (NH4-N), and total phosphorous (TP) (Table 3-5). Data in Table 3-5 is combined wastewater from the Kalispell service area and the Evergreen service area. Average TSS, TKN, and TP concentrations for this data are within typical values. The average BOD5 concentration is slightly higher than recommended design concentrations but still well within expected values. Influent TKN is sampled approximately once per month, so performing a 30-day moving average does not return a valid maximum month value. An alternative method that can be used is the statistical analysis method which determines the probability of occurrence Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-5 of influent loads. If the data fits a log-normal distribution well, then the 91.7th percentile (11/12th percentile) can be used to estimate the maximum month condition. Figure 3-1 and Figure 3-2 demonstrate a good log-normal distribution of the TKN data in mg/L and lb/d, respectively. Therefore, the 91.7th percentile is used to determine the maximum month values. Figure 3-1. Log-Normal Distribution of TKN mg/L Data Figure 3-2. Log-Normal Distribution of TKN lb/d Data Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-6 Table 3-5. Combined Influent Wastewater Characterization1 Parameter Unit Average Maximum Month Maximum Day BOD5 mg/L 267 371 699 TSS mg/L 220 305 680 TKN mg/L 43.9 51.9 54.5 NH4-N mg/L 29.8 46.1 55.1 NO3-N mg/L 0.29 0.69 2.73 TN mg/L 44.2 52.6 57.2 TP mg/L 5.0 7.2 8.8 Temp DegC 14.4 N/A 20.4 BOD5 lb/d 5,886 7,175 13,542 TSS lb/d 4,856 7,198 20,901 TKN lb/d 972 1,163 1,764 NH4-N lb/d 661 1,015 1,479 NO3-N lb/d 6.5 20 140 TN lb/d 979 1,183 1,904 TP lb/d 111 152 254 1 Characterization of Kalispell and Evergreen combined influent wastewater for 2012 - 2017. Chemical oxygen data (COD) data for influent wastewater was also obtained from the City and compared to BOD data (Table 3-6). The average ratio of BOD to COD for the select samplings is 0.357, which is within the typical range of 0.3 to 0.8 for untreated wastewater. Table 3-6. Influent BOD and COD Characterization Sample Date BOD (mg/L) COD (mg/L) BOD:COD Ratio 6/1/2017 228 793 0.288 6/6/2017 243 636 0.382 6/16/2017 235 707 0.332 6/23/2017 260 771 0.337 7/11/2017 250 644 0.388 7/21/2017 281 675 0.416 8/3/2017 283 802 0.353 Average 254 718 0.357 Characterization of the wastewater from the Evergreen service only was also performed. Average values for January 2012 through December 2017 are presented in Table 3-7. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-7 Table 3-7. Evergreen Only Wastewater Characterization Parameter Unit Average Flow MGD 0.382 BOD5 mg/L 190 TSS mg/L 138 TKN mg/L 58.0 NH4-N mg/L 46.1 NO3-N mg/L 0.047 TN mg/L 58.047 TP mg/L 7.11 BOD5 lb/d 605 TSS lb/d 440 TKN lb/d 185 NH4-N lb/d 147 NO3-N lb/d 0.15 TN lb/d 185.15 TP lb/d 23 3.2.5 Per Capita Wastewater Demands For the purpose of calculating per capita flow and loading, the flow and loading data summarized in Table 3-1 and Table 3-5 were used in conjunction with the average population calculated for the period of review, 2012 through 2017. Table 3-8 presents the per capita wastewater flow demands for the total population served by the Kalispell AWWTP. Discussions with City staff indicate the majority of the Evergreen District population is connected, i.e., there may be a small number of septic systems but those are very limited. Therefore, the estimated Evergreen District population is included in the total population served. An average demand of 99 gallons per capita per day (gpcd) was calculated for the period of review as total influent (Kalispell and Evergreen). The calculated per capita value is comparable to the commonly used value of 100 gpcd. It is common to evaluate the most recent three to five years of data to capture recent trends within an area or system. However, the Sewer Collection System Facility Plan evaluated a longer period of review which included two years that had higher per capita flow demands. The per capita demand of 108 gpcd is an increase from the value calculated in the 2008 Wastewater Facility Plan Update, which was 106 gpcd. It is important to note the 108 gpcd only Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-8 looked at flows from the Kalispell conveyance, and did not include Evergreen flows. A higher per capita demand is conservative for planning purposes, but it should be noted that national trends show that water usage is being reduced by efficient water fixtures and water conservation. The 108 gpcd calculated for the Sewer Collection System Plan will be used for the current analysis in order to provide consistency across both facility plans. The flow rates used in the per capita wastewater demands include residential, commercial, visiting/employment population, and inflow and infiltration (I/I). Employment and residential populations are assumed to have grown, and will continue to grow, at the same rate (or proportionately to each other). Table 3-8. Per Capita Wastewater Flow Demands Year City of Kalispell Population Evergreen Sewer District Population Total Population Served Per Capita Ave Flow Demand (gpcd) Per Capita Max Month Flow Demand (gpcd) Per Capita Max Day Flow Demand (gpcd) 2012 20,614 5,007 25,621 107 150 196 2013 21,054 5,109 26,163 94 110 169 2014 21,619 5,214 26,833 101 140 317 2015 22,031 5,320 27,351 95 137 211 2016 22,761 5,477 28,238 93 106 159 2017 23,212 5,587 28,799 103 186 301 Average 991 138 226 gpcd = gallons per capita per day 1 The annual average per capita flow demand of 108 gpcd calculated in the Sewer Collection System Facility Plan will be used for the current analysis. See Section 3.2.5 above for explanation. Table 3-9 presents influent per capita values for BOD5, TSS, TKN, NH4-N, and TP. The estimated residential BOD5 contribution is 0.22 pounds per capita per day. This value is within the range found in reference literature (Table 3-10) of 0.17 pounds per capita per day (without garbage grinders) to 0.22 pounds per capita per day (with garbage grinders) recommended by Ten State Standards for design of new systems. The estimated per capita suspended solids contribution is 0.18 pounds per capita per day. This value is slightly lower than the Ten States Standards range of 0.20 pounds per capita per day (without garbage grinders) to 0.25 pounds per day (with garbage grinders) recommended for new systems. The estimated per capita total phosphorus contribution is 0.004 pounds per capita per day. This value is slightly below the range found in reference literature of 0.0066 to 0.0132 pounds per capita per day recommended by Wastewater Engineering, Treatment/Disposal/Reuse, Metcalf and Eddy, Second Edition. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-9 Table 3-9. Per Capita Wastewater Load Values Parameter Unit Average Maximum Month Maximum Day BOD5 lb/capita/d 0.217 0.245 0.401 TSS lb/capita/d 0.179 0.227 0.526 TKN lb/capita/d 0.036 0.0391 0.045 NH4-N lb/capita/d 0.024 0.027 0.034 TP lb/capita/d 0.0041 0.0047 0.0058 lb/capita/d = pounds per capita per day 1 Estimated using the calculated TKN maximum month value and average 2012 – 2017 population. Table 3-10. Typical BOD and TSS per Capita Loads for Domestic Wastewater Source BOD5 (lbs/capita/d) TSS (lbs/capita/d) Range Without Grinders With Grinders Range Without Grinders With Grinders Metcalf & Eddy 0.11 – 0.26 0.18 0.22 0.13 – 0.33 0.20 0.33 Ten State Standards 0.17 – 0.22 0.17 0.22 0.20 – 0.25 0.20 0.25 lbs/capita/d = pounds per capita per day 3.3 Population Projections and Planning Period The City of Kalispell Planning Department has indicated an average annual growth rate of 2.0% should be used for planning purposes. The Evergreen District population is assumed to grow at the same annual rate as the City of Kalispell. Table 3-11 presents the total projected population served by the Kalispell AWWTP. The facility will be evaluated under a 20-year planning horizon as this is commonly considered the typical useful life of mechanical equipment. Additionally, a 20-year planning period is required by MDEQ Circular DEQ-2, Section 11.23. 3.4 Projected Wastewater Flow and Loads Projections of future wastewater flow and loading are usually performed by first determining current unit loadings for the existing population, commercial, and industrial contributions. These unit loadings, in conjunction with population projections, can then be used to determine future treatment plant flows and loads. Industrial, commercial, governmental, and multi-family loading is expected to remain constant in Kalispell throughout the planning period. The ratio of these contributions to residential contribution is also expected to remain constant. To simplify the analysis of future flow and loading to the wastewater treatment plant, per capita flow and loading values will be based on the residential population. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-10 Table 3-11. Projected Service Populations Year City of Kalispell Population Evergreen Sewer District Connected Population Total Population Served 2018 23,676 5,699 29,375 2023 26,140 6,292 32,432 2028 28,861 6,947 35,808 2033 31,865 7,670 39,535 2038 35,182 7,8991 43,081 1 The Evergreen Sewer District Population is capped at 7,899 which is the equivalent population to reach the Interlocal Agreement max flow rate of 0.805 MGD. Projected flow and loading values have been developed as shown in Table 3-12. The per capita unit loadings were combined with population and peaking factors to generate projections of future flow and loading. The Sewer Collection System Facility Plan recommended a decreasing peaking factor as the service population increases over time. This recommendation is incorporated in determining projected peak hour flows as designated in the footnotes of Table 3-12.The projections are for the current year (2018), 2023, 2028, 2033, and 2038 conditions. It should be noted again that applying the current per capita flow and wasteloads to the projected population assumes both a linear growth in commercial and industrial wasteloads that are tied to projected population growth. In addition, it also assumes that flows will increase at the same rate as the loads. Long term trends (almost universally around the US) show that flow increases at a lesser rate than loads. This is due to gradual reduction in per capita water use. The reduction is a result of passive conservation due to water use efficiency programs regulated by the Department of Health, plumbing code changes, more efficient appliances (washer, dishwasher), and active conservation through a more environmentally conscious public. Kalispell’s current per capita wastewater flow of 108 gal per person per day is higher than the United States average of approximately 90 gal per person per day. Meaning per capita flows have the potential to continue decreasing for an extended period of time. The long term implication for Kalispell is that the plant’s hydraulic capacity will likely be sufficient much longer than its treatment capacity. When plant capacity is related to flow, it should be footnoted with the per capita capacity so the overall capacity is accurately stated. Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-11 Table 3-12. Projected Influent Flows and Loads Parameter Unit 2018 2023 2028 2033 2038 Total Population Served by AWWTP N/A 29,375 32,432 35,808 39,535 43,081 Flow Average MGD 3.17 3.50 3.87 4.27 4.65 Max Month MGD 4.06 4.49 4.95 5.47 5.96 Max Day MGD 6.62 7.31 8.07 8.92 9.72 Peak Hour MGD 10.47 11.211 12.182 13.243 14.194 BOD Average lb/d 6,386 7,051 7,785 8,595 9,366 Max Month lb/d 7,210 7,960 8,789 9,703 10,574 Max Day lb/d 11,787 13,014 14,369 15,864 17,287 TSS Average lb/d 5,261 5,809 6,414 7,081 7,716 Max Month lb/d 6,681 7,376 8,144 8,991 9,798 Max Day lb/d 15,464 17,073 18,850 20,812 22,679 TKN Average lb/d 1,051 1,161 1,281 1,415 1,542 Max Month lb/d 1,146 1,265 1,397 1,542 1,680 Max Day lb/d 1,317 1,454 1,605 1,772 1,931 NH4-N Average lb/d 714 788 870 961 1,047 Max Month lb/d 801 884 976 1,078 1,174 Max Day lb/d 992 1,095 1,209 1,335 1,455 TP Average lb/d 120 132 146 161 176 Max Month lb/d 137 151 167 185 201 Max Day lb/d 171 188 208 230 250 1 Peaking Factor of 3.20 2 Peaking Factor of 3.15 3 Peaking Factor of 3.10 4 Peaking Factor of 3.05 Kalispell AWWTP 2018 Facility Plan Update Chapter 3 - Basis of Planning Page 3-12 3.5 Environmental Factors Another facet of long-term facility planning is to consider the possible effects of climate change and how those effects could affect the operations of the AWWTP. Predictions for Kalispell and the surrounding Northern Rockies are that climate change will result in noticeable temperature increases in the near future. A rise in temperatures could have a variety of consequences for all facets of water management in the Flathead Valley. While it is difficult to predict specifically how climate change will affect Kalispell in the coming decades, new planning challenges will almost certainly be introduced for all entities within the water industry. Consequently, the City could benefit by considering the effects of climate change in its long-term planning efforts. A warmer climate could alter long-term weather patterns and disrupt historical climate benchmarks, such as the onset of spring snowmelt. However, the extent of these changes and disruptions will vary by region and are difficult to predict accurately. In northwest Montana, the best science and model guidance suggests that the region will see warmer temperatures and modest precipitation increases, with most of that increased precipitation arriving during the winter months. These predictions are summarized and explored more deeply in the 2015 Montana State Water Plan developed by the Montana DNRC. As a warmer atmosphere can hold more moisture, one might expect less precipitation. However, warmer temperatures could result in more precipitation falling as rain instead of snow at lower elevations, and the frequency of rain on snow events during the winter could also increase. This could mean a shift in the timing of spring runoff to earlier in the season, and higher likelihoods of significant flooding during the spring and early summer months. The greatest potential risk posed to the AWWTP by climate change is the higher potential for significant precipitation events. This could contribute to significantly elevated runoff, increasing influent flow rates to the AWWTP. The runoff could carry more debris potentially making it difficult to maintain influent screening and grit removal processes. Another treatment problem posed by such a scenario would be the increased turbidity levels of the incoming influent. Increased turbidity is one of the climate related treatment challenges specifically noted by the Water Research Foundation in its 2018 State Survey of Climate Change Resiliency Efforts. The amount of sediment suspended in influent water is increased by extreme precipitation events. Increased sediment loading could pose treatment challenges for the City. Another challenge potentially facing the AWWTP by climate change is low stream flow in Ashley Creek. A consequence of warmer summer temperatures will be elevated evapotranspiration rates, which could negate any of the moisture gained from additional winter precipitation. In such a scenario, the possibility of a sudden onset of drought conditions during the summer months would be more likely. The MDEQ Fact Sheet for the AWWTP lists the seven-day, ten year low flow condition (7Q10) for Ashley Creek as 7 cfs. If flash drought conditions were to develop during a prolonged period of hot, dry weather, it is possible that the 7Q10 value could change, raising permit compliance issues. CHAPTER 4 EXISTING WASTEWATER TREATMENT FACILITY Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-i Contents 4 Existing Facility Evaluation ............................................................................................................... 4-1 4.1 Introduction ............................................................................................................................. 4-1 4.2 History of the Facility .............................................................................................................. 4-1 4.2.1 Original Construction & 1984 Sludge Management Project...................................... 4-1 4.2.2 1990 Biological Nutrient Removal Project ................................................................. 4-3 4.2.3 2007-2008 Phase 1 Improvements Project ............................................................... 4-4 4.2.4 Facility Awards .......................................................................................................... 4-5 4.3 Description of Existing Facilities ............................................................................................. 4-7 4.3.1 Preliminary Treatment ............................................................................................... 4-7 4.3.2 Influent Pumping Station ........................................................................................... 4-9 4.3.3 Primary Clarification ................................................................................................ 4-10 4.3.4 Flow Equalization Basin .......................................................................................... 4-15 4.3.5 Secondary Treatment .............................................................................................. 4-17 4.3.6 Secondary Clarification ........................................................................................... 4-27 4.3.7 Effluent Filtration ..................................................................................................... 4-31 4.3.8 UV Disinfection ........................................................................................................ 4-32 4.3.9 Reaeration Basin ..................................................................................................... 4-34 4.3.10 Primary Sludge Fermentation ................................................................................. 4-36 4.3.11 Anaerobic Digestion ................................................................................................ 4-38 4.3.12 Thickened Waste Activated Sludge (TWAS) Storage Tank .................................... 4-42 4.3.13 Sludge Thickening ................................................................................................... 4-43 4.3.14 Biosolids Dewatering ............................................................................................... 4-45 4.3.15 Biosolids Disposal ................................................................................................... 4-47 4.3.16 Odor Control ............................................................................................................ 4-50 4.3.17 Non-potable Water System ..................................................................................... 4-52 4.3.18 Chemical Storage and Feed Systems ..................................................................... 4-53 4.3.19 Electrical and SCADA Systems .............................................................................. 4-56 4.3.20 Facility Staffing ........................................................................................................ 4-56 4.3.21 Administration and Laboratory Building .................................................................. 4-57 4.4 Existing Facilities Survey...................................................................................................... 4-59 4.4.1 Survey Item 1: Single Greatest Challenge at AWWTP ........................................... 4-59 4.4.2 Survey Item 2: Prioritization of Work Related Subjects .......................................... 4-59 4.4.3 Survey Item 3: Treatment Process Functional Rating ............................................ 4-60 4.4.4 Survey Item 4: Time Consuming Areas .................................................................. 4-61 4.4.5 Survey Item 5: Self-rating of Facility ....................................................................... 4-62 4.4.6 Survey Item 6: Expenditure Choice ......................................................................... 4-62 4.5 Facility Evaluation Summary ................................................................................................ 4-62 Tables Table 4-1. Preliminary Treatment Equipment Summary ............................................................................ 4-9 Table 4-2. Influent Pumping Station Equipment Summary ...................................................................... 4-10 Table 4-3. Primary Treatment Equipment Summary ............................................................................... 4-12 Table 4-4. EQ Basin Equipment Summary .............................................................................................. 4-16 Table 4-5. Bioreactor Design Criteria Summary ...................................................................................... 4-18 Table 4-6. Bioreactor Equipment Summary ............................................................................................. 4-19 Table 4-7. Bioreactor Cell Summary ........................................................................................................ 4-23 Table 4-8. Average Effluent Nutrient Concentrations .............................................................................. 4-27 Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page ii Table 4-9. Secondary Clarification Equipment Summary ........................................................................ 4-29 Table 4-10. Effluent Filtration Equipment Summary ................................................................................ 4-32 Table 4-11. UV Disinfection Equipment Summary................................................................................... 4-34 Table 4-12. Primary Sludge Fermentation Equipment Summary ............................................................ 4-37 Table 4-13. Anaerobic Digestion Equipment Summary ........................................................................... 4-40 Table 4-14. TWAS Tank Equipment Summary ........................................................................................ 4-43 Table 4-15. Sludge Thickening Equipment Summary ............................................................................. 4-44 Table 4-16. Biosolids Dewatering Equipment Summary ......................................................................... 4-47 Table 4-17. Biosolids Disposal Equipment Summary .............................................................................. 4-49 Table 4-18. Odor Control Equipment Summary ...................................................................................... 4-52 Table 4-19. Non-Potable Water System Equipment Summary ............................................................... 4-52 Table 4-20. Chemical Systems Equipment Summary ............................................................................. 4-55 Figures Figure 4-1. Kalispell AWWTP Process Flow Diagram ............................................................................... 4-1 Figure 4-2. AWWTP Aerial circa June 1990 .............................................................................................. 4-3 Figure 4-3. AWWTP Aerial circa May 2004 ............................................................................................... 4-6 Figure 4-4. AWWTP Aerial circa July 2017 ................................................................................................ 4-6 Figure 4-5. Influent Perforated Plate Screen ............................................................................................. 4-7 Figure 4-6. Construction Photo of Grit Removal Chamber ........................................................................ 4-8 Figure 4-7. Grit Washer .............................................................................................................................. 4-8 Figure 4-8. Influent Pumps ....................................................................................................................... 4-10 Figure 4-9. Primary Clarifiers .................................................................................................................. 4-11 Figure 4-10. Primary Sludge Pumps ........................................................................................................ 4-12 Figure 4-11. Influent TSS and Primary Effluent TSS ............................................................................... 4-14 Figure 4-12. Influent BOD and Primary Effluent BOD ............................................................................. 4-14 Figure 4-13. Flow Equalization Basin ...................................................................................................... 4-15 Figure 4-14. EQ Basin Operation Setpoints ............................................................................................. 4-16 Figure 4-15. Bioreactor Flow Diagram – All Possible Alignments ........................................................... 4-17 Figure 4-16. Bioreactor Overview ............................................................................................................ 4-20 Figure 4-17. Cell 6 of the Anoxic Zone .................................................................................................... 4-21 Figure 4-18. Aeration Zone of Bioreactor ................................................................................................. 4-21 Figure 4-19. Aeration Blowers ................................................................................................................. 4-22 Figure 4-20. Bioreactor Flow Diagram - Current Operation ..................................................................... 4-26 Figure 4-21. MLSS vs. Effluent Temperature .......................................................................................... 4-26 Figure 4-22. Secondary Clarifier 3 ........................................................................................................... 4-28 Figure 4-23. Final Effluent TSS ................................................................................................................ 4-30 Figure 4-24. Bioreactor Sludge Volume Index ......................................................................................... 4-30 Figure 4-25. Ultraviolet (UV) Disinfection ................................................................................................. 4-33 Figure 4-26. Effluent Reaeration Basin .................................................................................................... 4-34 Figure 4-27. Reaeration Basin DO and Temperature .............................................................................. 4-35 Figure 4-28. Floodplain Map for Kalispell AWWTP ................................................................................. 4-36 Figure 4-29. Reaeration Basin during 1997 Flood ................................................................................... 4-36 Figure 4-30. Single-Stage, Primary Sludge Fermenter ............................................................................ 4-37 Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-iii Figure 4-31. Primary Digester .................................................................................................................. 4-39 Figure 4-32. East Secondary Digester ..................................................................................................... 4-40 Figure 4-33. TWAS Storage Tank Exterior .............................................................................................. 4-42 Figure 4-34. TWAS Storage Tank Interior ............................................................................................... 4-42 Figure 4-35. DAFT Units .......................................................................................................................... 4-44 Figure 4-36. Volute Press with Two Drums Installed ............................................................................... 4-46 Figure 4-37. Filtrate Waste Pumps .......................................................................................................... 4-46 Figure 4-38. Truck Used for Hauling Dewatered Biosolids ...................................................................... 4-49 Figure 4-39. Compost Biofilter Beds for Odor Control ............................................................................. 4-51 Figure 4-40. Chemical Tanks ................................................................................................................... 4-53 Figure 4-41. DAFT and Belt Filter Press Polymer Pumps ....................................................................... 4-54 Figure 4-42. Kalispell AWWTP Org Chart ................................................................................................ 4-57 Figure 4-43. Laboratory Facilities ............................................................................................................ 4-58 Figure 4-44. Exterior of Administration Building....................................................................................... 4-58 Figure 4-45. Survey Item 1 Results ......................................................................................................... 4-59 Figure 4-46. Survey Item 2 Results – Importance of Work Related Items .............................................. 4-60 Figure 4-47. Survey Item 3 Results - Treatment Processes Rating ........................................................ 4-61 Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page iv This page is intentionally left blank. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-1 4 Existing Facility Evaluation 4.1 Introduction The City of Kalispell currently operates a biological nutrient removal (BNR) facility for wastewater treatment. The facility discharges treated effluent to Ashley Creek. A process diagram for the Advanced Wastewater Treatment Plant (AWWTP) is shown in Figure 4-1. This chapter evaluates the existing capacity of treatment processes and facility equipment as compared to the projected flows and loads developed in Chapter 3. A brief description of each treatment plant process is included in this chapter. Areas within the facility that are identified as requiring improvements are further evaluated in Chapter 5. Figure 4-1. Kalispell AWWTP Process Flow Diagram 4.2 History of the Facility Major facility improvements occurred in 1984, 1990, and 2007-2008. 4.2.1 Original Construction & 1984 Sludge Management Project Major project elements for the original facility construction included: • Grit chamber & influent flume • Control house • 50-FT diameter primary clarifier • 60-FT diameter primary clarifier Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-2 • Oxidation tower/trickling filters • Aeration basin • Filtration & pump building • Chlorine storage and Sludge oxidation room • 75-FT diameter secondary clarifier • Lift station • Chlorine contact chamber • Sludge storage In 1984 the Sludge Management Facilities project was constructed. Major project elements included: • 35-FT diameter gravity thickener • 50-FT diameter primary digester • Two, 50-FT diameter secondary digesters • Digester control building Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-3 Source: Goggle Earth Figure 4-2. AWWTP Aerial circa June 1990 4.2.2 1990 Biological Nutrient Removal Project In 1990 the Kalispell Advanced Wastewater Treatment Facility - Biological Nutrient Removal (BNR) project was constructed. The BNR process was designed to replace an outdated activated biofilter treatment plant and was based on the most advanced technology in biological nutrient removal at the time. The project was necessary to meet stringent discharge limitations set in the City’s MPDES permit issued in November 1988. The modified University of Cape Town (MUCT) treatment process was selected as the preferred process since it minimized necessary tank size to maintain consistent phosphorus removal to less than 1.0 mg/L. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-4 Other innovations for the 1990 project included continuous backwash sand filtration and ultraviolet light disinfection. At the time of process conception in 1990, the facility was one of the most technologically advanced wastewater treatment plants in the State of Montana and the entire United States. The new facility was commissioned on October 22, 1992. Major project elements included: • Influent pumping station • Headworks • Primary clarifiers • Equalization tank • Bioreactor • Secondary clarifier • Return activated sludge (RAS) Building • Effluent filtration & Ultraviolet (UV) Disinfection • Effluent reaeration • Biosolids handling and Chemical feed • Process Control & Administration Building • Fermenter 4.2.3 2007-2008 Phase 1 Improvements Project Development and demand for municipal wastewater services in the Flathead Valley during 2004 and early 2005 were increasing at a very rapid rate. As a result, the City initiated the Phase 1 Improvements Project. The project combined the following major elements: • Headworks expansion to accommodate increasing flows, including new fine screen, grit removal, and appurtenances • Influent pump station capacity expansion by addition of a sixth pump and upsizing the effluent forcemain to the primary clarifiers • Existing primary clarifier modifications for improved hydraulic functionality and sludge pumping • Secondary treatment upgrades and expansion: o Conversion to Modified Johannesburg Process o Bioreactor volume expansion o Fine bubble aeration o New blower building o New Secondary clarifier and RAS/WAS pump station improvements • UV disinfection system replacement and increased capacity Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-5 • Existing thickener demolition and addition of new static primary sludge fermenter • Conversion of existing fermenter to thickened waste activated sludge storage • Odor control expansion and enhancement throughout the plant with improved air collection and handling and a new biofilter treatment system • Sludge truck storage facility addition See Figure 4-3 and Figure 4-4 for an aerial photograph of the facility prior to and following the Phase 1 Improvements Project, respectively. 4.2.4 Facility Awards The Kalispell AWWTP is an award winning facility. Among the prestigious awards that have been bestowed upon the City and staff are the: • Biosolids Award from the Montana Water Environment Association • Commendation of Excellence Award from the Flathead Basin Commission • System of the Year Award from Montana Rural Water Systems • Three Region VIII first place Operations and Maintenance Excellence Awards from the U.S Environmental Protection Agency; 1997, 2003, and 2007 • Two national first place U.S Environmental Protection Agency Clean Water Act Recognition Awards, 2003 and 2007 • American Council of Engineering Companies of Montana Honor Award, 2010 Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-6 Source: Goggle Earth Figure 4-3. AWWTP Aerial circa May 2004 Source: Goggle Earth Figure 4-4. AWWTP Aerial circa July 2017 Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-7 4.3 Description of Existing Facilities 4.3.1 Preliminary Treatment Raw wastewater enters the facility from the City’s sewer collection system on the north side of the Headworks Building via a 36-inch diameter pipeline. A 14-inch diameter forcemain conveying wastewater from the Evergreen Water and Sewer District ties into the 36-inch pipe upstream of the Headworks Building. Preliminary treatment within the Headworks Building involves screening and grit removal processes. The screening process removes debris from the influent wastewater which prevents damage to downstream equipment. Items such as rags, clothes, etc. that can get wrapped around pump impellers are removed by this process. Wastewater passes through a perforated plate screen (Figure 4-5) that has circular openings of 8 mm. Captured screenings are lifted out of the channel and directed to a discharge outlet by a scrapper-roller mechanism. Screenings then pass through the screenings washer/compactor where they are washed with non-potable water and compacted to produce dry, clean screenings for disposal. A channel adjacent to the perforated plate screen channel contains a manual bar screen which is used in emergency situations and during maintenance activities. Screened raw wastewater flows to the grit removal basins and screenings are transported to the local landfill. Figure 4-5. Influent Perforated Plate Screen The purpose of grit removal is to provide protection of downstream equipment from abrasive materials and to prevent the accumulation of excessive amounts of grit in the primary clarifiers. Screened wastewater enters a dual-chamber vortex grit removal chamber (Figure 4-6) where organic material is separated from grit. Degritted wastewater continues in the treatment process and the grit is cleaned by the grit washer, (Figure 4-7) then disposed of as solids waste. The influent wastewater flowrate is measured at a 3- foot wide parshall flume. Wastewater then flows by gravity to the Influent Pumping Station. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-8 Figure 4-6. Construction Photo of Grit Removal Chamber Figure 4-7. Grit Washer A summary of Preliminary Treatment equipment at the Kalispell AWWTP is presented in Table 4-1. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-9 Table 4-1. Preliminary Treatment Equipment Summary Equipment Description/Quantity Influent Manual Bar Screen Quantity Type Bar Spacing 1 Manually cleaned ¾ IN Influent Perforated Plate Screen Quantity Type Perforation Opening Peak Flow Capacity Max Head Loss at 20% Blinded 1 Perforated Plate Screen 8 mm 16.57 MGD 12 IN Screenings Washer/Compactor Quantity Capacity 1 20 ft3/hr Grit Removal Chamber Quantity Type Peak Flow Capacity 1 Circular Forced Vortex 22 MGD Grit Washer Quantity Type Hydraulic Slurry Capacity Grit Processing Capacity 1 Vortex/Coanda Effect 250 gpm 2 ft3/hr Influent Flow Measurement Quantity Type Throat Width Maximum Flow Rate 1 Parshall Flume 3 FT 32.6 MGD Process and Equipment Assessment The major equipment in the Headworks Building was placed into service during the Phase 1 Improvements Project and is generally in good condition. The screening and grit removal equipment have been documented to have adequately passed a peak flow of 10 MGD. Malodorous air within the Headworks Building is being handled and treated to appropriate levels. The existing preliminary treatment equipment has sufficient capacity to handle the wastewater flows projected for the planning horizon. However, a single perforated plate screen and washer/compactor means the manual bar screen must be used during perforated plate screen maintenance activities. Operators also indicate the lead time for spare parts for the screenings equipment can be significant, leading to increased time maintaining the manual bar screen. 4.3.2 Influent Pumping Station The Influent Pumping Station is located northwest of the Headworks Building and is used to convey wastewater to the primary clarifiers. Wastewater from the grit removal chamber flows by gravity through the parshall flume to the wet well of the pumping station. Six self-priming, centrifugal pumps (Figure 4-8) convey flow to the primary Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-10 clarifiers through an 18-inch diameter pipeline and a 30-inch diameter pipeline. Five of the influent pumps were put into service in 1992. The sixth pump was installed in 2009 during the Phase 1 Improvements Project. Variable frequency drives (VFDs) were installed on two existing pumps at that time as well. Each pump has a 10-inch suction pipe that extends down into the wet well and a 10-inch discharge pipe is routed to a common 18-inch header. The six, variable speed pumps operate to maintain a wet well level at the level setpoint. Figure 4-8. Influent Pumps A summary of Influent Pumping Station equipment at the Kalispell AWWTP is presented in Table 4-2 Table 4-2. Influent Pumping Station Equipment Summary Equipment Description/Quantity Influent Pumps Quantity Type Horsepower, each Drive Capacity, each Total Firm Pump Capacity 6 Self-priming, Centrifugal 40 hp Variable Frequency 2,150 gpm 9,630 gpm (13.87 MGD) Process and Equipment Assessment The equipment in the Influent Pumping Station is generally in good condition. Performance of the pumping equipment has been adequate, with the system estimated to have pumped approximately 10 MGD in March 2017 during peak flow events. Wear and maintenance conditions have been typical. The Influent Pumping Station total firm pump capacity of 13.87 MGD is exceed during the planning horizon. The projected peak hour flow for the year 2038 is 14.19 MGD. Increased pumping capacity will be required prior to 2038. 4.3.3 Primary Clarification The purpose of primary clarification is to reduce suspended solids in wastewater by removing readily settable solids and floating material. The Kalispell AWWTP has two rectangular primary clarifiers (Figure 4-9), which are located adjacent to the flow Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-11 equalization tank. The clarifiers were constructed with common walls to the equalization tank in order to reduce construction costs. The original designers felt the cost savings outweighed the operational benefits of circular clarifiers. Wastewater enters the clarifiers from a flow splitting structure which evenly distributes influent flow to the clarifiers. During periods of peak flow, primary effluent may also be directed to an equalization basin. The clarifiers are each equipped with a longitudinal and cross flow plastic chain sludge collector drive. An enclosure over the chain and flight drive mechanism is located at the influent end, between the two clarifiers. It was added by plant staff sometime after startup to protect the mechanism from weather conditions. The flights attached to the chain serve to scrape sludge from the bottom of the clarifiers and as scum skimmers at the liquid surface. Settled sludge is delivered to a sump where it is then pumped by three (two duty, one standby) pumps (Figure 4-10) to the fermenter. Normal operation for the primary sludge pumps are based on a timer or constant flow set points. Skimmer pipes at the end of the clarifiers collect the scum from the water surface. Scum drains by gravity to a scum decant tank and is pumped by two pumps to the primary digester or flows by gravity to the thickened waste activated sludge (TWAS) tank. A summary of Primary Treatment equipment at the Kalispell AWWTP is presented in Table 4-3. Figure 4-9. Primary Clarifiers Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-12 Figure 4-10. Primary Sludge Pumps Table 4-3. Primary Treatment Equipment Summary Equipment Description/Quantity Primary Clarifiers Quantity Type Effective Size, each Length, inside dimension Width, inside dimension Surface Area Total Weir Length Effective Volume, each Design Capacity, each Surface Overflow Rate at Design Flow Rate Hydraulic Retention Time 2 Rectangular 90 FT 22 FT 1,980 FT2 88 FT/clarifier 165,000 gallons 1,280 gpd/ft2 at Avg Flow 2,500 gpd/ft2 at Max Day Flow 1.25 hours at Max Day Flow 2.3 hours at Avg Flow Primary Sludge Pumps Quantity Type Horsepower, each Drive Capacity, each 3 (2 duty, 1 standby) Rotary Lobe 5 hp Variable Frequency 100 gpm Primary Scum Pumps Quantity Type Horsepower, each Capacity, each 2 Horizontal, Progressive Cavity 5 hp 100 gpm Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-13 Process and Equipment Assessment The primary clarifiers and pumping equipment are generally in good condition for their age. However, as with most rectangular clarifiers, operation and maintenance of the sludge collection mechanism is problematic as the chains stretch with age and the flights can get stuck or stressed. The chains have broken or jumped off the sprockets at times and new chains have been installed in the clarifiers in hopes of minimizing this occurrence. The operation and maintenance required for the mechanisms is extensive. Once every year, each of the clarifiers has to be taken out of service and the mechanisms inspected. The chains are replaced approximately every five years. The primary clarifiers perform adequately under most circumstances to reduce influent TSS and BOD concentrations. Influent TSS is reduced from an average of 220 mg/L to 58 mg/L (Figure 4-11), a 74% reduction. Influent BOD is reduced from an average of 268 mg/L to 133 mg/L (Figure 4-12), a 50% reduction. The design overflow rate is typical for a clarifier of this type and size. The primary clarifiers have sufficient hydraulic capacity to handle the projected peak hour flows for the planning period. Surface overflow rates were also compared to the projected flows to evaluate process performance of the clarifiers within the planning period. The following surface overflow rates should not be exceeded per design literature (Metcalf and Eddy, Wastewater Engineering 4th Edition, 2003) and regulatory requirements (MDEQ Circular DEQ-2, Section 72.21): • 1,000 gal/ft2•d at design average flow • 3,000 gal/ft2•d at design peak hourly flow The surface overflow rate criteria at average flows would be exceeded prior to 2033 at an average flow of approximately 4.0 MGD. Utilizing peak flows attenuated by the equalization basin, the surface overflow rate criteria at peak hourly flow would also be exceeded prior to 2033 at a peak hour flow of approximately 12.0 MGD. It is anticipated that the primary clarifiers will require expansion by approximately 2030 in proportion to increasing influent flow rates. If the primary clarification capacity is not expanded, there will be a subsequent degradation of effluent quality on a peak flow basis. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-14 Figure 4-11. Influent TSS and Primary Effluent TSS Figure 4-12. Influent BOD and Primary Effluent BOD Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-15 4.3.4 Flow Equalization Basin The flow equalization basin is adjacent to the two primary clarifiers. The equalization basin attenuates peak hydraulic conditions and enables the bioreactor to receive a consistent and adequate carbon source. It was constructed to capture wastewater in the basin during high influent flows and send the wastewater back to the head of the plant during low flow periods. The temporary off-loading of organic loading and peak flows facilitates improved biological nutrient removal performance, especially nitrification, by sustaining favorable environmental conditions for microbiology in the bioreactor. Flow to the equalization basin (Figure 4-13) is from the primary effluent channel through a pipe with a motorized control valve during periods of peak flow. During periods of low flow, the influent valve closes and the primary effluent in the equalization basin flows by gravity back to the Influent Pumping Station wet well via another pipe with a motorized control valve. Flow is then conveyed back into the primary clarifiers by the influent pumping station. Typical setpoints for valve position at various times throughout the day during fill and drain modes are presented in Figure 4-14. “Cannon-type” hose valves placed on both sides of the basin allow for washdown as necessary. The hose valves are used to rinse the basin which helps with odor mitigation. Figure 4-13. Flow Equalization Basin Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-16 A summary of the EQ Basin equipment at the Kalispell AWWTP is presented in Table 4-4. Table 4-4. EQ Basin Equipment Summary Equipment Description/Quantity Equalization Basin Quantity Length, inside dimension Width, inside dimension Side Water Depth Effective Volume 1 90 FT 51 FT 10-12 FT 375,000 gallons Process and Equipment Assessment As described above, the equalization basin consists of a concrete tank, an influent channel, and motorized valves that control influent and effluent flow. It does not include any other electrical or mechanical equipment. The equalization basin is in good condition. The City had the interior concrete walls of the equalization basin coated in 2015 with a Xypex sealant followed by a Sherwin Williams Coal Tar Epoxy. The north, south, and east walls were coated. The west wall was not coated as it will be removed in the future to expand equalization basin capacity. The equalization basin performs as designed. Influent flows and loads to the bioreactor are moderated on a typical day. This peak flow attenuation assists the facility in achieving exemplary effluent quality on a routine basis. The basin has a total effective volume of 375,000 gallons which represents approximately 13.9 percent of the current Figure 4-14. EQ Basin Operation Setpoints Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-17 average flow. The basin volume can theoretically completely equalize dry weather peak diurnal flows under current conditions. This has been confirmed through empirical evidence as City staff indicate the equalization basin is currently completely filled and then emptied within a 24 hour period. As daily average flow rates increase, the effect of the equalization basin is minimized. Also, flow attenuation during peak flow events such as those experienced in March 2017 is no more than a few hundred thousand gallons per day, or less than 5 percent of the peak flow rate. Performance of a biological nutrient removal facility is optimal when influent flows can be equalized. The existing basin can equalize average daily flows until an estimated 2.8 MGD, so additional capacity will be required soon. 4.3.5 Secondary Treatment Primary clarifier effluent flows to the bioreactor which consists of Cells 1 through 15 (Figure 4-15). Cells 12 and 13 are not shown as they are planned to be constructed as aeration basins in the future. The secondary treatment process at the Kalispell AWWTP is a biological nutrient removal (BNR) process referred to as the modified Johannesburg process. This process is utilized for optimum biological oxygen demand, nitrogen, and phosphorus removal using a combination of pre-anoxic, anaerobic, anoxic, and aerobic basins. Primary effluent and return activated sludge (RAS) are mixed in the pre-anoxic zone which is followed by an anaerobic zone where volatile fatty acids (VFAs) are introduced. Primary sludge fermentation is used to create the short chain VFAs for use by microorganisms which facilitate phosphorus release in the anaerobic zone of the bioreactor. Following the anaerobic zone is the anoxic zone where mixed liquor recycle is introduced and nitrate is converted to nitrogen gas, which is released to the atmosphere, and water, resulting in a reduction of nitrogen in the wastewater. A subsequent swing zone can be aerobic or anoxic. The final zone of the bioreactor is the aeration zone. BOD is consumed and phosphorus uptake occurs in the aerobic zone. Figure 4-15. Bioreactor Flow Diagram – All Possible Alignments A summary of the design criteria for the bioreactor and related equipment is presented in Table 4-5 and Table 4-6, respectively. Figure 4-16, Figure 4-17, and Figure 4-18 present photographs of the bioreactor. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-18 Table 4-5. Bioreactor Design Criteria Summary Criteria Quantity Design Flow Average Day 5.4 MGD Biochemical Oxygen Demand (BOD) Effluent 10 mg/L (30 Day Average) Phosphorous Influent Effluent 4.5 – 6.5 mg/L as P 1.0 mg/L as P (30 Day Average) Total Nitrogen Effluent <10 mg/L as N (Annual Average) Effective Volume Total Aerobic 2.86 Million Gallons 1.53 Million Gallons Avg Hydraulic Retention Time (HRT) Total 12.7 Hours Avg Solids Retention Time (SRT) Total 12.5 Days Mixed Liquor Suspended Solids (MLSS) Total 3,500 mg/L Temperature Design Minimum 12 °C 10 °C Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-19 Table 4-6. Bioreactor Equipment Summary Equipment Description/Quantity Mixing Cell 1 – 5 Mixers Quantity, total Type Horsepower, each Cell 6 and 7 Mixers Quantity, total Type Horsepower, each Quantity, total Type Horsepower, each Cell 8 and 9 Mixers Quantity, total Type Horsepower, each Cell 14 and 15 Mixers Quantity, total Type Horsepower, each 5 Vertical Mixer 3 hp 4 Vertical Mixer 7 hp 4 Submersible 4 hp 4 Vertical Mixer 10 hp 8 Submersible 4 hp Aeration Blowers Quantity Type Horsepower, each Drive Capacity, each Firm Capacity 5 (2 duty, 3 standby) Multistage Centrifugal 125 hp Variable Frequency 2,200 scfm 8,800 scfm Mixed Liquor Recycle (MLR) Pumping Quantity Type Horsepower, each Drive Capacity, each 3 Propeller 20 hp Variable Frequency 6,000 gpm Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-20 Figure 4-16. Bioreactor Overview Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-21 Figure 4-17. Cell 6 of the Anoxic Zone Figure 4-18. Aeration Zone of Bioreactor Mixing and aeration are accomplished separately within each zone. Mixing within Cells 1 to 9 is primarily provided by vertical, bridge-mounted impeller type mixers. Mixing in Cells 14 and 15 is provided by submersible mixers. Aeration can be provided to Cells 8, 9, 10, 11, 14, and 15 by multistage centrifugal blowers (Figure 4-19) through fine bubble diffusers. Air supply is controlled by maintaining a pressure setpoint in the air header. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-22 The control system also modulates control valves to maintain a dissolved oxygen setpoint in each of the bioreactor cell zones independently of other zones. Mixed liquor is conveyed by three propeller type pumps the effluent of Cells 14 and 15 to Cell 6, 7, or 8 of the bioreactor via a 30-inch diameter pipeline. VFAs are pumped from the fermenter via a 4-inch diameter pipeline to Cell 1, 2, or 3. RAS discharges into the pre-anoxic zone of the bioreactor, Cell 1 or Cell 2. By adjusting the inlet and discharges of the recycle stream, and the discharge point of the RAS, the relative sizes of the four reaction zones (pre-anoxic, anaerobic, anoxic, and aerobic) can be optimized for a wide variety of influent characteristics and operating conditions. Scum from the bioreactor flows by gravity to the scum decant tank adjacent to the primary clarifiers. The 13 bioreactor cells offer a lot of flexibility for facility operation and maintenance, including the ability to take Cells 1 - 5 and Cells 10 – 11 off-line for maintenance. Figure 4-19. Aeration Blowers Theory of Operation Biochemical oxygen demand (BOD), which are carbon-based constituents found in wastewater, is assimilated throughout the process with uptake of readily biodegradable products in the anaerobic zone, utilization in support of the denitrification reaction in the anoxic zones, and reduced through residual assimilation and conversion in the aerobic zones. The detention time needed for BOD removal is much less than that for nitrification. Thus a high degree of BOD removal is achieved because the plant is operated to achieve full nitrification. BOD removal via microbial activity occurs in Cells 10 through 15 under aerobic conditions. The BOD removal mechanism occurs through the removal of solids as waste activated sludge (WAS). BOD concentrations are reduced to 10 mg/L or less on a 30 day average. The BNR process requires an environment favorable to the microscopic organisms performing the nutrient removal be maintained within a series of cells. The nitrogen Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-23 removal mechanism is nitrification/denitrification whereby ammonia is converted to nitrate (nitrification) which is then converted to nitrogen gas (denitrification). Nitrification occurs in Cells 8 through 15 under aerobic conditions. Denitrification can occur in Cells 6 through 9 under anoxic conditions, i.e., mixed but not aerated. Total nitrogen concentrations are reduced to less than 10 mg/L on an annual average. The phosphorous removal mechanism at the Kalispell AWWTP is enhanced biological phosphorous removal (EBPR) which is the conversion of soluble phosphorus to particulate phosphorus. Phosphorus is removed by exposure to an anaerobic environment followed by an aerobic environment. When exposed to anaerobic conditions (devoid of oxygen and nitrate) in Cells 3, 4 and 5, phosphorus is released by the biological population. When re-exposed to aerobic conditions in Cells 8 through 15, phosphorus is taken up by microbes called phosphorous accumulating organisms (PAOs) in excess of the normal amount necessary for them to thrive. Fermenter supernatant is sent to the anaerobic cells of the bioreactor to facilitate this process. The supernatant contains VFAs which are used for energy by anaerobic microorganisms to release phosphorus in a form which can be used by aerobic microorganisms in subsequent bioreactor cells. The aerobic microorganisms then uptake phosphorus for producing energy and other biomass. Aerobic microorganisms are able to consume more phosphorus that is produced in the anaerobic cells thereby decreasing the total phosphorus in the final effluent. The phosphorus removal mechanism is the removal of this phosphorus rich biology as WAS. Return activated sludge (RAS) contains nitrate that would inhibit the release of phosphorus in the anaerobic zones. Therefore the function of Cells 1 and 2 is to denitrify the nitrate contained in RAS. Total phosphorus concentrations are reduced to below 1.0 mg/L on a 30 day average. Solids in the bioreactor are controlled by wasting sludge directly from the bioreactors, or by capturing a portion of the return activated sludge. In either case, the waste sludge is directed to the dissolved air flotation thickeners (DAFT) units that are discussed in Section 4.3.13. Table 4-7 presents a summary of the bioreactor cells and typical mode of operation. Table 4-7. Bioreactor Cell Summary Description Quantity/Mode Cell 1 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 26 FT 26 FT 15 FT 0.076 Million Gallons Pre-Anoxic Cell 2 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 26 FT 26 FT 15 FT 0.076 Million Gallons Pre-Anoxic Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-24 Description Quantity/Mode Cell 3 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 26 FT 26 FT 15 FT 0.076 Million Gallons Anaerobic Cell 4 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 26 FT 26 FT 15 FT 0.076 Million Gallons Anaerobic Cell 5 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 26 FT 26 FT 15 FT 0.076 Million Gallons Anaerobic Cell 6 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 26 FT 15 FT 0.188 Million Gallons Anoxic/Anaerobic Cell 7 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 26 FT 15 FT 0.188 Million Gallons Anoxic Cell 8 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 39 FT 15 FT 0.288 Million Gallons Anoxic/Aerobic Cell 9 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 39 FT 15 FT 0.288 Million Gallons Anoxic/Aerobic Cell 10 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 39 FT 15 FT 0.288 Million Gallons Aerobic Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-25 Description Quantity/Mode Cell 11 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 66 FT 39 FT 15 FT 0.288 Million Gallons Aerobic Cell 14 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 130 FT 10 IN 32 FT 15 FT 0.475 Million Gallons Aerobic Cell 15 Effective Size Length, inside dimension Width, inside dimension Side Water Depth Effective Volume Mode of Operation 130 FT 10 IN 32 FT 15 FT 0.475 Million Gallons Aerobic Current Bioreactor Operation and Optimization Experiments Figure 4-20 shows the existing flow alignments for the current bioreactor operation. The current operation is as follows: • Cell 1 is offline • Primary effluent and RAS are conveyed to Cell 2 • VFAs are conveyed to Cell 3 • Mixed liquor recycle (MLR) is pumped to Cell 6 • Cells 10, 11, and 15 are offline but aerated Mixed liquor suspended solids (MLSS) concentration in the aeration basin from January 2012 through December 2017 averaged 2,510 mg/L and is adjusted seasonally, i.e., increased during colder weather and decreased during warmer weather. Figure 4-21 presents MLSS concentration in the aeration zone of the bioreactor and final effluent temperature. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-26 Figure 4-20. Bioreactor Flow Diagram - Current Operation Figure 4-21. MLSS vs. Effluent Temperature Treatment performance at this award winning facility continues to be excellent. Table 4-8 presents average effluent water quality for the AWWTP from 2012 through 2017. °C Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-27 Table 4-8. Average Effluent Nutrient Concentrations Parameter Unit Average BOD5 mg/L 4.40 TN mg/L 7.72 TKN mg/L 1.36 NH4-N mg/L 0.21 NO3-N mg/L 6.36 TP mg/L 0.13 City staff have recently been experimenting to optimize plant performance with a step feed mode of operation where a portion of primary effluent is conveyed to various downstream bioreactor cells to facilitate denitrification. This mode of operation reduces nitrate concentrations and total nitrogen. Preliminary results have been promising and additional optimization experiments continue. Process and Equipment Assessment Generally, all equipment associated with the bioreactors is in good condition for its age. The concrete of the bioreactors themselves is in good condition, and most gates and control structures are also in good condition. The vertical mixers and submersible mixers have generally operated without significant problems. The aeration blowers have performed adequately; however, newer technologies are available that are more energy efficient and have a smaller footprint. Aeration within a BNR facility is a large portion of the electrical costs, so the City might consider an evaluation of the existing blowers to determine if implementing a newer technology, turbo blowers for example, would lead to an agreeable payback period. Funding and rebate programs are available within the industry that focus on energy efficient equipment. The secondary treatment system performance has been exemplary, due to its conservative design nature, diligent plant management, and continued study by operations staff. The capacity of the system has been stressed multiple times during sustained high flow, low temperature influent wastewater events that effectively eliminate biological phosphorus removal and significantly disrupt nitrification. Chemical addition, proper changes implemented by operations staff, and quick response time are the primary reasons that effluent permit violations do not occur. Current performance levels of the bioreactor will be difficult to maintain as permit effluent limits continue to be lowered. The City should continue the optimization experiments within the facility and consider permanent installation of equipment to support the step feed mode of operation if results remain positive. Beyond optimizing existing infrastructure, however, additional treatment may be necessary to reach predicted future permit limits that will likely push the limits of technology. 4.3.6 Secondary Clarification The settled sludge is conveyed to two processes in the plant, the first being to the bioreactor as return activated sludge (RAS) and the second to the dewatering process as Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-28 waste activated sludge (WAS). Effluent from bioreactor Cell 14 and Cell 15 flows over weir gates to the secondary clarifier diversion structure. Weir gates in the structure are used to control flow to three 75-foot diameter secondary clarifiers. Each secondary clarifier receives flow from the bioreactor through a 30-inch diameter pipe which reduces to a 24-inch diameter pipe just prior to entering the clarifier. Secondary Clarifiers 1 and 2 have suspended, two-sided inboard launders with a vertical scum baffle plate. Secondary Clarifier 3 (Figure 4-22) has an inboard launder with current density baffle. A 24-inch diameter pipe conveys effluent from each secondary clarifier. Secondary effluent from all three clarifiers combines in a single 30-inch pipe which conveys flow to the effluent filtration process. Each clarifier has a central, bottom well that is connected to the RAS pumps by an 8-inch suction line (Secondary Clarifiers 1 and 2) or 12-inch suction line (Secondary Clarifier 3). The RAS pump station is located in the basement of a building between Secondary Clarifiers 1 and 2. Two duty and one standby RAS pump primarily serve Secondary Clarifiers 1 and 2. Those pumps are 15-hp, variable speed, recessed impeller pumps. A 15-hp, variable speed, screw centrifugal pump serves as the primary RAS pump for Secondary Clarifier 3. Piping interconnections provide operational flexibility for use of RAS pumps with all clarifiers. Solids settled in the clarifiers are pumped via a 10-inch or 18-inch diameter pipe to either the pre-anoxic zone of the bioreactor, as described in Section 4.3.5, or conveyed to the basement of the Process and Control Building for sludge thickening. Figure 4-22. Secondary Clarifier 3 The clarifiers are equipped with vertical scum baffles which prevent scum and other floating material from entering the clarifier effluent channel. A surface scum removal mechanism directs the scum into a trough. Scum from all three clarifiers flows by gravity to a collection pit on the east side of the RAS Building. Secondary scum is pumped by two, 5-hp, centrifugal chopper scum pumps, which are located in the RAS Building Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-29 basement. The scum is pumped from the collection pit to a scum decant tank adjacent to the primary clarifiers. From the dectant tank, scum is pumped to the primary digester or flows by gravity to the TWAS storage tank. A summary of Secondary Clarification equipment at the Kalispell AWWTP is presented in Table 4-9 Table 4-9. Secondary Clarification Equipment Summary Equipment Description/Quantity Secondary Clarifiers Quantity Type Diameter, inside dimension Side Water Depth Surface Area, each Weir Length, each Design Surface Overflow Rate (equalized flow) Average Flow Maximum Week Flow Maximum Day Flow 3 Circular 75 FT 15 FT 4,420 FT2 215 FT 382 gpd/ft2 753 gpd/ft2 875 gpd/ft2 RAS Pumps Quantity Type Horsepower, each Drive Capacity, each 4 Recessed Impeller (3), Screw centrifugal (1) 15 hp Variable Frequency 1,250 gpm (3), 1,500 gpm (1) Secondary Scum Pumps Quantity Type Horsepower, each Capacity, each 2 Centrifugal Chopper 5 hp 200 gpm Process and Equipment Assessment The secondary clarifiers and associated pumps are in good condition. The secondary clarifiers have performed adequately under most conditions. Under normal circumstances the effluent TSS is less than 10 mg/L, and is often less than 5 mg/L (Figure 4-23). This high level of performance is influenced by the settling characteristics of the mixed liquor suspended solids of the bioreactor, which is commonly quantified as sludge volume index (SVI). A SVI of 100 to 150 mL/g, or less, is recommended for good sludge settling. SVI values are typically less than 150 mL/g at the Kalispell AWWTP (Figure 4-24). Clarifier sizing, sludge removal mechanism, and related clarifier design features also contribute to the outstanding effluent quality. The secondary clarifiers have sufficient hydraulic capacity to handle the projected peak hour flows for the planning period. Secondary clarifiers are generally designed utilizing two main criteria, surface overflow rates and solids loading rates. Both criteria were used to evaluate the process performance of the clarifiers within the planning period. The following surface overflow rates should not be exceeded per design literature and regulatory requirements: Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-30 • 400 - 700 gal/ft2•d at design average flow (Metcalf and Eddy, Wastewater Engineering 4th Edition, 2003) • 1,000 gal/ft2•d at design peak hourly flow (MDEQ Circular DEQ-2, Section 72.22) Figure 4-23. Final Effluent TSS Figure 4-24. Bioreactor Sludge Volume Index Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-31 The surface overflow rate criteria would not be exceeded at average flows during the planning period. Utilizing peak flows attenuated by the equalization basin, the surface overflow rate criteria at peak hourly flow would also not be exceeded during the planning period. The following solids loading rates should not be exceeded per Metcalf and Eddy, Wastewater Engineering 4th Edition, 2003: • 1.0 – 1.5 gal/ft2•hour at design average flow • 1.8 gal/ft2•hour at design peak hourly flow Additionally, the following solids loading rates should not be exceeded per MDEQ Circular DEQ-2, Section 72.22: • 35 gal/ft2•day at design max day flow The recommended solids loading rate criteria above would not be exceeded at average, maximum day, or equalized peak hour flows during the planning period. Therefore, it is not anticipated that additional secondary clarification capacity will be required during the planning period. The primary performance issue has been algal growth in the clarifier launders. Algae builds up on the weirs, eventually sloughs off, and collects in the effluent filter tanks reducing tank volume and negatively impacting filter and ultraviolet disinfection performance. The clarifiers also attract water fowl which are a nuisance to plant operations. Secondary Clarifier 3 has weir brushes that help mitigate the algal growth issue, but modifications to the clarifiers are required to permanently address algal growth and water fowl issues. 4.3.7 Effluent Filtration Effluent filtration is designed to further remove suspended solids, which in turn reduces concentrations of phosphates, ammonia, and BOD. Reducing TSS should also improve the effectiveness of the downstream ultraviolet disinfection system. Secondary clarifier effluent flows via a 30-inch diameter pipe to the effluent filters. The deep-bed sand filters are located in the lower level of the Process and Control Building. The four filters are upflow, continuous backwash filters, each consisting of four modules. Secondary effluent flows into the bottom of the filters and is evenly distributed into the sand beds via a plenum space, pipe connections, and an inverted “V” distribution ring associated with each module. The filtrate exits the top of the sand beds, flows over a weir and through a flume into a channel. The effluent channel conveys the filtrate to the ultraviolet disinfection system. The continuous backwash is accomplished by drawing the dirty sand at the bottom of the filter into the suction of an airlift pump. The pumping action scours the sand and a gravity separator at the top of the filter returns the cleaned sand to the filter bed. Reject water is collected from all 16 modules in a reject chamber and returned to the filtrate waste sump which conveys the water to Cell 8 or Cell 9 of the bioreactor. A compressor located adjacent to the filters provides air for the airlift pumps. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-32 A summary of Effluent Filtration equipment at the Kalispell AWWTP is presented in Table 4-10. Table 4-10. Effluent Filtration Equipment Summary Equipment Description/Quantity Effluent Filters Quantity Modules Cells Type Design Flow Rate Hydraulic Flow Rate Design TSS Influent Effluent Filter Design, each module Bed Surface Area Filtration Bed Depth Filtration Rate Filter Capacity Backwash Type Backwash Rate Media Type Effective Size Uniformity Coefficient 16 4 (4 modules per cell) Upflow, continuous backwash 6.9 MGD (Peak Hour Flow) 11.0 MGD (Peak Wet Weather Flow) 5 – 20 mg/L < 10 mg/L 50 FT2 40 IN 6 gpm/ft2 300 gpm Air scour by air lift pump 10 gpm/filter Silicia Sand 1.2 – 1.4 mm 1.5 Air Compressors Quantity Horsepower, each System Design Capacity, each 2 (1 duty, 1 standby) 25 hp 42.7 scfm at 35 psig 85.4 scfm at 100 psig Process and Equipment Assessment The filters are in poor condition given their age. Several modules are missing the sand media, there is severe metal corrosion, and the system has failing gaskets. As stated above, the filters provide an additional measure of solids reduction, and associated BOD and TP reduction, under normal circumstances. Additionally, the filters serve as a backup unit process when an upset condition in the secondary system results in elevated levels of suspended solids. The filters are maintenance intensive and extremely difficult to maintain due to the design and limited access restraints. Secondary clarifier effluent TSS is typically less than the design influent TSS to the filters, but the filters still function to improve solids concentration in the effluent and non- potable water system. However, when there has been a plant upset, or secondary clarifier suspended solids have been elevated due to peak flow events, the filters have become a hydraulic restriction and are operationally ineffective. An evaluation of the effluent filters should consider hydraulics, future regulations, and potential effluent limits. 4.3.8 UV Disinfection The purpose of the ultraviolet (UV) disinfection system is to inactivate disease causing organisms in plant effluent prior to being discharged to Ashely Creek. Water from the Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-33 effluent filters flows through an open channel to the UV system (Figure 4-25). UV disinfection is a horizontal, open channel, gravity flow, low-pressure high-intensity system. Disinfected effluent then passes into a control structure, through a 36-inch pipe to the effluent magnetic flow meter, and finally through the reaeration basin to the outfall at Ashley Creek. Two UV banks with 80 bulbs per bank have a dosage of 21,500 microWatts- second/square centimeter and were designed for an average flow of 7.24 MGD. The UV system was installed in a 36-foot long, 40-inch wide, 78-inch deep channel located in the western portion of lower level of the Control Building. A signal from the effluent flow meter is sent to the UV equipment programmable logic controller to control the UV system. The UV equipment is capable of turning on and off banks and varying the intensity of the banks based on flow and a manually entered UV transmittance value. An automatic cleaning system contains wipers that reduces fouling of UV lamps. Wipers clean all modules in a bank simultaneously. The cleaning system can be adjusted to operate automatically as frequently as once every two hours or operated manually. A portable davit crane and a 4-point lifting sling provided by the manufacturer is used to remove UV modules from the channel for maintenance purposes. Figure 4-25. Ultraviolet (UV) Disinfection A summary of UV Disinfection equipment at the Kalispell AWWTP is presented in Table 4-11. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-34 Table 4-11. UV Disinfection Equipment Summary Equipment Description/Quantity UV Disinfection Quantity Banks Bulbs per bank Type Design Flow Rate Average Peak 2 80 Horizontal, open channel 7.24 MGD 22.09 MGD Process and Equipment Assessment All UV disinfection equipment and systems are in adequate condition after approximately ten years in service. Process performance is good with effluent fecal coliform values averaging 3.90 colony forming units per 100 mL from January 2012 through December 2017. The capacity to disinfect current and future flows during the planning period is adequate. 4.3.9 Reaeration Basin The reaeration basin increases the dissolved oxygen (DO) concentration in the effluent prior to discharge to Ashley Creek. Final effluent flows from the UV disinfection channel through a 24-inch diameter pipe to the effluent reaeration basin located on the southwest end of the AWWTP site (Figure 4-26). Low pressure air is supplied by the bioreactor aeration air blowers and fed into the basin by a 3-inch diameter pipe to fine bubble diffusers set on the floor of the basin. Final effluent leaves the basin through a 24-inch diameter pipe and is discharged into Ashley Creek. Figure 4-26. Effluent Reaeration Basin Process and Equipment Assessment The reaeration basin system has performed well to maintain effluent DO concentrations within a desirable range. The average DO concentration was approximately 9.3 mg/L Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-35 from January 2012 through December 2017. Effluent DO concentration fluctuates seasonally as oxygen solubility changes with temperature (Figure 4-27). The basin is expected to continue to perform adequately during the planning period. The reaeration basin is located within the 100-year floodway (Figure 4-28) and has been subject to flooding under extreme events, such as occurred in the spring of 1997 (Figure 4-29). Raising the walls and covering the structure would mitigate flooding events and dampen effluent temperatures. Figure 4-27. Reaeration Basin DO and Temperature Source: FEMA Flood Map Service Center °C Reaeration Basin Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-36 Figure 4-28. Floodplain Map for Kalispell AWWTP Figure 4-29. Reaeration Basin during 1997 Flood 4.3.10 Primary Sludge Fermentation The primary purpose of the fermenter is to produce supernatant which contains VFAs utilized in the secondary treatment process to facilitate phosphorous removal. See Section 4.3.5 for additional information. Primary sludge pumps convey sludge from the primary clarifiers to a single-stage fermenter (Figure 4-30) through a 6-inch diameter pipe. Sludge enters the 45-foot diameter fermenter through the side of the unit and discharges within the center well. In the anaerobic environment of the fermenter, hydrolysis biodegradation of the organic material occurs. Solids retention times are limited to prevent the formation of acetogenic and methanogenic organisms which can upset the system. The solids retention time is 6-15 days and the solids removal mechanism is picket fence style with a plow/squeegee mounted at the bottom that pushes sludge to a sump located in the center of the fermenter. The fermenter sludge pump is used to convey sludge from a sump in the fermenter to the primary digester. The fermenter sludge pump is controlled by manually setting the stroke cycle timers at the local manufacturer’s control station. The fermenter sludge pump runs continuously but the stroke rate is adjusted seasonally. A progressive cavity pump can be used to recirculate sludge within the fermenter. Scum is collected from the surface of the fermenter and is pumped to the digesters. The scum pump is controlled by a local control station at the wetwell. The stroke cycle time can be adjusted at the manufacturer’s control station located at the pump. Hydraulic retention times within the fermenter are controlled using elutriation water, normally non-potable water, but primary clarifier effluent can be used as an alternate source. An oxidation reduction potential (ORP) probe monitors anaerobic conditions in the fermenter. Operators manually adjust elutriation water based on readout values from the ORP probe. Reaeration Basin Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-37 Fermenter supernatant flows over a launder weir to a buried concrete wet well. The fermenter supernatant pumps convey supernatant to the anaerobic zone of the bioreactors and operate to maintain a wet well level setpoint. Figure 4-30. Single-Stage, Primary Sludge Fermenter A summary of Primary Sludge Fermentation equipment at the Kalispell AWWTP is presented in Table 4-12. Table 4-12. Primary Sludge Fermentation Equipment Summary Equipment Description/Quantity Fermenter Quantity Type Diameter Depth Solids Retention Time Solids Blanket Depth 1 Single Stage 45 FT 25 FT 6 – 15 days 8 – 15 FT Fermenter Sludge Pump Quantity Type Capacity 1 Air Diaphragm 100 gpm Fermenter Recirculation Pump Quantity Type Horsepower, each Drive Capacity, each 1 Progressive Cavity 15 hp Variable Frequency 200 gpm Fermenter Scum Pump Quantity Type Capacity 1 Air Diaphragm 100 gpm Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-38 Equipment Description/Quantity Fermenter Supernatant Pumps Quantity Type Horsepower, each Drive Capacity, each 2 Horizontal, Screw Centrifugal 7.5 hp Dual speed 240 gpm Elutriation Water Pump Quantity Type Horsepower Drive Capacity 1 Rotary Lobe 20 hp Variable Frequency 160 gpm Process and Equipment Assessment Primary sludge fermenter performance has been good since it was placed into service. The simple one-stage system was previously selected due to the simplicity of operation and ability to better control corrosion compared to the previous two-stage system. City staff have, however, periodically experienced difficulties with fermenter operation. One potential reason for the operational challenges could be that the fermenter is under loaded. As growth continues in the service area and loading to the facility increases, fermenter operation could ease. Another problematic issue has been with the pumping capacity of the fermenter supernatant pump. City staff indicate the pump is not reaching its rated capacity and nearly half of the VFAs being conveyed are distributed to the Influent Pumping Station instead of directly to the bioreactor. This pumping system should be evaluated as VFAs are critical to phosphorus removal within the facility. The system capacity is adequate for the planning period flows and loads. The fermentation system is a critical component to achieving low effluent phosphorus concentrations. Therefore, City staff have discussed temporarily taking the fermenter out of service to assess the condition of the fermenter coatings and internal mechanical components. 4.3.11 Anaerobic Digestion The primary purpose of anaerobic digestion is biosolids stabilization and reduction. Anaerobic digestion is the process by which organic materials in an enclosed vessel are decomposed and stabilized by microorganisms in the absence of oxygen. The process is widely used to treat wastewater solids because it reduces the feed solids volume and mass. Digester gas, or biogas, is produced which contains approximately 65% methane and is usable as a fuel. The biosolids which are a byproduct of the anaerobic process contain all the water, all the nutrients, and approximately half of the carbon from the incoming materials. The Kalispell AWWTP operates a two-stage, high rate anaerobic digestion system. The system consists of one primary digester (Figure 4-31) and two secondary digesters (Figure 4-32). All three digesters are concrete construction and 50-feet in diameter. The primary digester is 30 feet deep with a sloping bottom and a concrete cover. The Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-39 secondary digesters are 32-feet deep with a sloping bottom and floating steel covers. The covers have an 8½ -foot diameter opening. All of the digesters are equipped with a pressure relief vacuum breaker valve and a gas extraction system for methane gas. Sludge from the fermenter is conveyed to the primary digester. The primary digester also receives primary clarifier scum, secondary clarifier scum, and fermenter scum. Primary digester contents are heated by one of two hot water boilers and a heat exchanger. The primary digester is operated in the mesophilic range. The average operating temperature has been 97-100 °F in recent years. A top entry mixer operates continuously in the primary digester to keep the contents of the digester homogenous. Digested sludge flows by gravity from the primary digester to one of two secondary digesters. A digested sludge transfer pump can be used to transfer digester contents between any of the three digesters. The secondary digesters are used for solids-liquid separation prior to dewatering. Therefore, the secondary digesters are not heated but do have recirculation pumps and floating steel covers. A variable speed, positive displacement pump is used to convey digested sludge to the Sludge Handling room of the Process Building for dewatering. Biogas is collected from the primary and secondary digesters and used as an energy source for the main boilers, or the biogas is flared. Natural gas is also available as a backup energy source for the boilers. Figure 4-31. Primary Digester Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-40 Figure 4-32. East Secondary Digester A summary of Anaerobic Digestion equipment at the Kalispell AWWTP is presented in Table 4-13. Table 4-13. Anaerobic Digestion Equipment Summary Equipment Description/Quantity Primary Digester Quantity Type Diameter, inside dimension Depth Cover 1 Anaerobic 50 FT 30 FT Fixed concrete Primary Digester Mixer Quantity Type Horsepower 1 Top Entry 15 hp Secondary Digesters Quantity Type Diameter, inside dimension Depth Cover 2 Anaerobic 50 FT 32 FT Floating steel Digested Sludge Transfer Pump Quantity Type Horsepower Drive Capacity 1 Progressive Cavity 5 hp VFD 100 gpm Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-41 Equipment Description/Quantity Recirculation Pumps Quantity Type Horsepower, each Drive Capacity, each 2 Positive Displacement 30 hp Single Speed 4,650 gpm Heat Exchanger Quantity Capacity 1 500,000 btu/hr Process and Equipment Assessment A new primary digester cover and new top entry mixer were constructed in 2014. The interior of the new cover, upper portion of the digester walls, and interior of the concrete overflow box were all recoated with an elastomeric polyurethane. New digester gas piping and appurtenances were also installed. As part of an ongoing rehabilitation project, the interior and exterior coatings of the secondary digester covers are being replaced. One digester is taken out of service at a time and then emptied. The cover is removed from the digester and coatings removed by sandblasting. Gap areas in the cover showing corrosion are being seal welded. The interior components (steel covers, girders, rafters, and beams, etc.) are being recoated with a polyurethane coating. The exterior of the cover was coated with an enamel. Work on the west secondary digester was completed during the summer of 2018 and work on the east secondary digester will occur during the summer of 2019. Given the recent and ongoing rehabilitation work, the digesters are generally in good physical condition and process performance has been acceptable. As with any anaerobic digestion system, a continuous maintenance and repair program is necessary to keep the gas and sludge components in service. The digester recirculation pumps are in fair condition. The pumps are over 20 years old and as such should be considered at the end of the life expectancy. Replacement of these pumps should be considered. Future loading rates to the digester within the planning period are estimated to be less than the recommended loading rates typical of similar facilities. Of concern, however, is that there is only a single primary digester. The current configuration means that only one digester is receiving the entire volatile suspended solid load. A configuration with two primary digesters would provide more operational flexibility and process stability. Digesters do require maintenance and occasional cleaning, and the current design does not allow for an extended period of downtime, while still maintaining adequate digestion. Another area of concern is the lack of redundancy with the heat exchanger which limits operational flexibility for City staff. If the existing unit fails, or is down for maintenance, then the ability to heat digester contents cannot be maintained. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-42 4.3.12 Thickened Waste Activated Sludge (TWAS) Storage Tank The TWAS storage tank can store thickened waste activated sludge from the dissolved air floatation thickeners or scum and foam from the bioreactor. The tank essentially serves as a “wide spot in the line” to store materials temporarily. The TWAS tank is a 40-foot diameter concrete tank with 18-foot 6-inch tall side walls. The tank is covered with 8-inch thick hollow core prestressed planks with 2-inch concrete topping. Eighteen inches of insulation at the perimeter of the tank slopes to 6-inch thick insulation at the center where a roof drain is located. Three 64-inch by 38-inch mixer hatches and one 18-inch hatch provide access to the tank. The tank exterior and interior are shown in Figure 4-33 and Figure 4-34, respectively. Figure 4-33. TWAS Storage Tank Exterior Figure 4-34. TWAS Storage Tank Interior Tank contents can be mixed and aerated to prevent settling, anaerobic conditions, and phosphorous release. Tank level is monitored for high and low level by a submerged Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-43 pressure transducer. A progressive cavity pump can convey TWAS storage tank contents to the Solids Handling Room for dewatering. A summary of the TWAS Storage Tank equipment at the Kalispell AWWTP is presented in Table 4-14. Table 4-14. TWAS Tank Equipment Summary Equipment Description/Quantity TWAS Tank Quantity Diameter, inside dimension Depth 1 40 FT 18 FT 6 IN Mixers Quantity Type Horsepower 2 Submersible 10 hp TWAS Tank Pump Quantity Type Horsepower Drive Capacity 1 Progressive Cavity 15 hp VFD 200 gpm Process and Equipment Assessment The interior coatings of the TWAS Storage Tank were replaced during the summer of 2018, as part of the secondary digester rehabilitation project occurring at the same time. Remedial work on areas of deteriorated concrete was performed inside the structure. The interior of the tank cover and walls to within one foot of the floor were coated with polyurethane. Drain piping inside the tank was also replaced as part of the project. Given the recent rehabilitation work on the TWAS tank it is generally in good physical condition. The tank is performing as intended and no additional work is recommended at this time. 4.3.13 Sludge Thickening The goal of sludge thickening is to increase solids concentration by reducing the water content, thereby decreasing the volume of sludge for additional treatment. Undigested WAS from the secondary clarifiers is thickened by dissolved air flotation thickening (DAFT) units and then combined with digested fermenter sludge prior to dewatering. Alternatively, unthickened, undigested WAS can be sent directly to dewatering. The DAFT system includes two, 200 ft2 units (Figure 4-35) located in the Sludge Handling Room in the lower level of the Process Building. The DAFT units provide a rapid method of thickening the WAS under aerobic conditions to prevent release of phosphorus from the sludge. Feed to each DAFT unit is through a 6-inch diameter pipe. The DAFT units receive WAS from the secondary clarifiers via the RAS line. A dedicated DAFT polymer system is utilized to dose polymer to the sludge feed line to the DAFT units. Compressed air is supplied to the bottom of the DAFT units, causing the sludge Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-44 (float) to rise to the top of the unit where it is scraped into a hopper by a continuously moving scraper mechanism. From there, two DAFT float pumps (one duty, one standby) transfer thickened WAS to dewatering equipment located in the same room. The DAFT float pumps are positive displacement pumps and are operated through a VFD. The DAFT float pumps can also convey thickened WAS to the Thickened WAS Storage Tank. There is some flexibility built into the sludge piping to allow thickened WAS to be pumped to the primary digesters and filtrate waste to be pumped back to the Headworks Building, if necessary. Subnatant from the bottom of the DAFT units flows by gravity to the Influent Pumping Station. Typical DAFT float concentration is about 2.2 percent solids. The mixed liquor waste pumps are used to waste solids from the bioreactor to the DAFT units. The pumps are located in the Sludge Handling Room. Although the pumps are in relatively good condition, they were abandoned soon after initial startup in favor of wasting from the RAS line. Anecdotal evidence is that wasting with mixed liquor waste pumps overwhelmed the DAFT units. By wasting from the RAS line, a reduced volume of waste sludge can be processed in the DAFT units compared to mixed liquor. Figure 4-35. DAFT Units A summary of the Sludge Thickening equipment at the Kalispell AWWTP is presented in Table 4-15. Table 4-15. Sludge Thickening Equipment Summary Equipment Description/Quantity Dissolved Air Flotation Tanks Quantity Size, each Loading, each 2 200 FT2 1.75 lb/ft2-hr Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-45 Equipment Description/Quantity DAFT Float Transfer Pumps Quantity Type Horsepower, each Drive Capacity, each 2 (1 Duty, 1 Standby) Positive Displacement 10 hp Variable Speed 10 – 50 gpm at 3.5% DAFT Recycle Pumps Quantity Type Horsepower Capacity 2 Horizontal, Centrifugal 15 hp 150 gpm Mixed Liquor Waste Pumps Quantity Type Horsepower, each Drive Capacity, each 2 Recessed impeller torque flow 5 hp Variable speed 530 gpm Process and Equipment Assessment The DAFT units have been in operation for over 20 years. Although the anticipated capacity of the DAFT units is sufficient for the planning period, the equipment is nearing the end of its useful life. Both of the DAFT tanks are exhibiting signs of severe corrosion, rendering the tank unusable. Additionally, the DAFT tanks require a larger footprint compared to many newer sludge thickening technologies. Rehabilitation or direct replacement of the DAFT units will be evaluated, as well as installation of alternative sludge thickening equipment. 4.3.14 Biosolids Dewatering The purpose of biosolids dewatering is to further reduce the volume of biosolids prior to hauling for disposal. A 2-meter belt filter press and a three drum volute press are available for biosolids dewatering. The 2-meter wide belt filter press is operated occasionally for solids and foam balance but is not currently used for day-to-day dewatering. Sludge feed typically consists of approximately 35 gpm of thickened WAS and 30 gpm of anaerobically digested sludge. A dry polymer, T-Flock 2621, is purchased from Thatcher Chemical in Missoula for use with the belt filter press. A designated polymer system is used to introduce polymer upstream of an in-line static mixer to improve flocculation and biosolids dewaterability. The belt filter press generates cake with approximately 14% solids concentration. Polymer usage has averaged 14 pounds per dry ton of solids. The volute press (Figure 4-36) operates 24 hours per day, 7 days per week. The sludge feed to the volute press is approximately 55 gpm of sludge wasted from the RAS pipeline having a 0.7% solids concentration and 15 gpm digested sludge which has a solids concentration of approximately 1.2%. A cationic emulsion polymer, BASF Zetag 8848, is currently used with the volute press. Typical dewatered biosolids concentrations average 14-16%. Polymer usage has averaged 22 active pounds of polymer per dry ton of solids. Dewatered biosolids from the belt filter press and volute press discharge to a common conveyor which has a maximum speed of 22 feet per minute. Filtrate from the belt filter Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-46 press and volute press flows by gravity to the filtrate waste sump. Filtrate is pumped from the sump to bioreactor Cells 8 or 9 by the Filtrate Waste Pumps (Figure 4-37). Figure 4-36. Volute Press with Two Drums Installed Figure 4-37. Filtrate Waste Pumps A summary of the Biosolids Dewatering equipment at the Kalispell AWWTP is presented in Table 4-16. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-47 Table 4-16. Biosolids Dewatering Equipment Summary Equipment Description/Quantity Belt Filter Press Quantity Belt width Horsepower Drive Solids Loading Hydraulic Loading 1 2 meter 3 hp Variable Frequency 1,290 lbs/hr dry weight solids 86 gpm at 3.0% solids Volute Press Quantity Horsepower, total Drive Solids Loading Hydraulic Loading 1 8.5 hp Variable Speed 630 lbs/hr 126 gpm at 1.0% solids Filtrate Waste Pumps Quantity Type Horsepower, each Capacity, each 2 Self-priming, Centrifugal 15 hp 415 gpm Process and Equipment Assessment The belt filter press has been in operation for approximately 20 years and is in fair condition. The press has historically been a source of costly repairs and resulted in continued downtime. The volute press provides operators with redundant dewatering equipment to mitigate some of the previous operational challenges experienced with the belt filter press. The belt filter press does give the operators the ability to balance the solids inventory within the facility relatively quickly due to its high loading capacity. The volute press was installed in March 2015. Dewatering performance of the volute press has varied since commissioning. As mentioned previously, the feed to the volute press is unthickened WAS and the press has produced cake within the preferred solids concentration range. However, the different mode of operation may be a factor when comparing full-scale equipment performance (polymer usage, cakes solids, etc.) to piloting efforts. Polymer usage, although higher than witnessed during piloting, is typical for similar applications. The City has adjusted volute press parameters and optimized dewatering performance. Additionally, the City invested in a third drum for the volute in 2018 to increase the capacity of the unit. The volute press operates automatically and unattended for continuous dewatering operations. This mode of operation has led to more consistent mixed liquor concentrations in the bioreactor according to City staff. 4.3.15 Biosolids Disposal Biosolids must be disposed of properly after dewatering. The City developed a Biosolids Management Plan in May 2018 to investigate alternative means to dispose of the biosolids produced at the AWWTP. Current disposal methods and the recommended alternative method presented in the Biosolids Management Plan are briefly summarized in this section. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-48 The City has a dual approach for dewatered biosolids disposal. A local composting facility in Olney, Montana called Glacier Gold Compost, Inc. is the primary disposal site. The second biosolids disposal site is the Flathead County landfill. The City has a 5-year agreement with Glacier Gold which is set to expire on March 31, 2019. The agreement was extended for an additional 5 years with consent by both parties. According to the agreement, the annual delivery amount shall not exceed 600 dry tons of dewatered biosolids in a calendar year and has a charge of $238 per dry ton. The City delivers dewatered biosolids to the Glacier Gold facility 5 – 7 times per week. The contracted amount of biosolids that can be delivered is determined by the capacity of the equipment at the composting facility and, therefore, cannot be increased. In the past five years, the annual amount of biosolids hauled to Glacier Gold has averaged approximately 503 dry tons. The agreement with Glacier Gold also states the dewatered biosolids delivered to the facility shall be between 13-20% solids concentration; the City’s historical average has been 14-15% solids concentration. Glacier Gold produces a Class A product for public use. As the City approached the annual delivery limit at Glacier Gold in the early 2000’s, a second biosolids disposal option was developed. In April 2004, the City began hauling dewatered biosolids to the Flathead County landfill located approximately ten miles from the AWWTP. The dewatered biosolids are incorporated with refuse at the landfill and covered within 24 hours. A formal contract with Flathead County for dewatered biosolids disposal at the landfill does not exist and disposal site access can be difficult depending on seasonal weather. Tipping fees at the landfill are $31.05 per wet ton. In 2018, the Flathead County Solid Waste Manager, under direction from the board of Directors, introduced minimum biosolid acceptance standards for the landfill. These standards were discussed with municipal stakeholders including the Cities of Whitefish, Columbia Falls, and Kalispell. Schedule deliveries were establish between the cities, and currently allows Kalispell to deliver two 18 yard trucks of biosolids to the landfill per week. Semiannual meetings are scheduled to be held between stakeholders and the County to continue collaborative disposal of biosolids. The City has three dump trucks (Figure 4-38) that are used for hauling dewatered biosolids. Each truck has a capacity of 20 cubic yards. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-49 Figure 4-38. Truck Used for Hauling Dewatered Biosolids A summary of the Biosolids Disposal equipment at the Kalispell AWWTP is presented in Table 4-17. Table 4-17. Biosolids Disposal Equipment Summary Equipment Description/Quantity Dewatered Biosolids Hauling Trucks Quantity Capacity 3 20 cubic yards Process and Equipment Assessment Given the challenges with approaching the contractual limits at Glacier Gold and the uncertainties and lack of guarantees with biosolids disposal at the county landfill, the City considered alternative biosolids management methods. The 2018 Biosolids Management Plan recommended the construction of a City owned and operated composting facility. The composting facility would produce a Class A biosolids product that could be sold or given to the general public, given to other City departments, or sold to local farmers. The proposed composting facility included: • An aerated static pile (ASP) method of composting. • A wood chipper, compost mixer, compost screen, ASP blowers, biofilter, biofilter blowers, skid steer, hopper/conveyor, front loader, and odor control. • A land requirement of approximately 10 acres. Potential sites included the 40 acres of land owned by the City of Kalispell south of Cemetery Road or the community of Bigfork sludge disposal site. The City began moving forward with conceptual design of a composting facility to be located on either the 40 acre site south of Cemetery Road or on the existing Bigfork sludge disposal site. Following City staff meetings with City Council, Glacier Gold personnel, and county landfill officials, the City has decided to postpone the composting facility. The City intends to renew the current agreement with Glacier Gold for another Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-50 five years. City staff also have verbal assurances from the county landfill board that delivering two loads of dewatered biosolids to the landfill per week is acceptable. The City would like to consider dewatering equipment that can produce a Class A biosolids product and an associated distribution site in lieu of a composting facility. That evaluation will be included in Chapter 5. 4.3.16 Odor Control The purpose of odor treatment is to reduce the amount of foul air emitted from the plant thereby reducing odor complaints from the public. Foul air from several process areas at the facility is exhausted to a compost filter bed treatment system. Covers on each unit process provide space for foul air collect. Each covered process is equipped with a foul air fan which pulls the foul air to the compost biofilter. The filter media is a mixture of sand, wood chips, compost media mix, aeration stone, and top bark dressing. The compost contains the “seed” material necessary to quickly establish the microbial growth throughout the media. Air is forced through the compost bed filter where malodorous air particles are sorbed and converted by microorganisms. Aerobic bacteria oxidize the reduced sulfur compounds typically found in sewage gasses converting these compounds into sulfates, sulfites, or elemental sulfur. The biological activity in the filter bed produces an acid byproduct that can eventually lower the pH of the media too low for adequate odor treatment. Areas at the facility with the highest intensity and/or volume of malodorous air are: • Headworks Building o Exhaust air from the influent channel and grit washer area is routed to the foul air collection system. A make-up air unit located on the roof provides supply air. • Influent Pumping Station o Air is pulled from the wet well and ties into the Headworks exhaust air. • Evergreen Influent Structure o A small exhaust fan in the building where the Evergreen forcemain enters the facility ventilates to the Influent Pumping Station wet well. • Fermenter o Ductwork connected to the aluminum cover of the Fermenter transports air to the Compost Filter Bed. • Anaerobic Digesters o Air is pulled from digester overflow boxes for Primary Digester No. 1 and Secondary Digesters No. 1 and No. 2 and routed to the foul air collection system. • Solids Handling o Air is pulled from the biosolids thickening and dewatering areas and routed to the foul air collection system. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-51 • TWAS Storage o Ductwork from TWAS Storage ties into an odor control fan. • Truck Storage o Two flexible hose ducts pull air from the Truck Storage Building. Six fiberglass fans ranging from 250 to 9,024 cfm transport air from each of those areas to two compost filter beds located in the southwest corner of the site treatment plant. Each bed is approximately 51 feet long, 42 feet wide, and 7 feet deep. Two blower fans rated at 15,000 cfm force air through the compost filter beds. The ventilation system removes foul air from sources of odor and helps prevent the buildup of dangerous and/or corrosive sewage gasses. Components of the ventilation system include fans, ductwork, grease filters and dampers. The foul air ducts are made of fiberglass. The ducts are sloped to specific trapped drainage points. Figure 4-39. Compost Biofilter Beds for Odor Control A summary of the Odor Control equipment at the Kalispell AWWTP is presented in Table 4-18. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-52 Table 4-18. Odor Control Equipment Summary Equipment Description/Quantity Odor Control Fans Quantity Horsepower Headworks Fan Influent Pumping Station Fan Fermenter Anaerobic Digestion, DAFT, and Truck Storage Fan Solids Handling Fan Evergreen Structure Exhaust Fan Capacity Headworks Fan Influent Pumping Station Fan Fermenter Anaerobic Digestion, DAFT, and Truck Storage Fan Solids Handling Fan Evergreen Structure Exhaust Fan 6 2.0 hp 0.5 hp 0.5 hp 1.2 hp 10.0 hp 0.33 hp 2,100 cfm 970 cfm 800 cfm 1,020 cfm 9,024 cfm 250 cfm Odor Control Blowers Quantity Horsepower, each Capacity, each 2 45 hp 15,000 cfm Process and Equipment Assessment The odor treatment system has been in operation for over 10 years and is performing well. The City replaced the wood chip media with larger bark material in May 2015. Replacement of the media should continue on a 5 – 7 year interval as a regular maintenance activity. City staff have indicated that a concrete stem wall is preferred around the perimeter of the biofilter beds as irrigation water that is offset from the side of the bed has resulted in the sides of the bed sloughing. This work would be recommended the next time the media is replaced. 4.3.17 Non-potable Water System The non-potable water system at the Kalispell AWWTP distributes non-potable water for use as spray water, washdown water, pump seal water, etc. throughout the plant. Disinfected secondary effluent is pumped by one of three non-potable pumps to the system. The pumps are located in the pipe gallery of the Process Building. The pumps are called to run based on system demand and operate based on system pressure. A summary of the non-potable water system equipment at the Kalispell AWWTP is presented in Table 4-19. Table 4-19. Non-Potable Water System Equipment Summary Equipment Description/Quantity Non-Potable Water Pumps Quantity Type Horsepower Drive Capacity, each 3 Centrifugal 15 hp Single Speed 150 gpm Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-53 Process and Equipment Assessment The non-potable water system has been operating according to design and pumping capacity is sufficient during the planning period. If a system is installed or constructed within the facility that has a high non-potable water demand, then the non-potable water system capacity should be reevaluated. 4.3.18 Chemical Storage and Feed Systems The chemical systems at the Kalispell AWWTP include the following: • Aluminum sulfate (alum) • Polymer for DAFT units • Polymer for belt filter press • Polymer for volute press A majority of the chemical equipment is located in the chemical room of the Process Building, see Figure 4-40 and Figure 4-41. Figure 4-40. Chemical Tanks Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-54 Figure 4-41. DAFT and Belt Filter Press Polymer Pumps Aluminum Sulfate (Alum) System The alum system can be used for chemical phosphorous removal when biological phosphorous removal methods are insufficient to meet permit limitations. Alum is received at the facility in liquid form and is pumped from the chemical feed room of the Process Building to bioreactor Cell 8, Cell 9, or effluent channel of Cells 11, 14, or 15. The alum system consists of the following components: • One 5,200 gallon FRP tank, • Two metering pumps, and • A calibration column DAFT Polymer System A polymer system is used with the DAFT units to increase sludge flocculation and enhance sludge thickening. The DAFT polymer system consists of the following components: • Two FRP tanks, • Two tank mixers, • Funnel educator, • Level control instruments, • Two metering pumps, • A calibration column, • Pushwater rotameter, and Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-55 • In-line static mixer Belt Filter Press Polymer System A polymer system is used with the belt filter press to increase sludge flocculation and enhance biosolids dewaterability. The belt filter press polymer system consists of the following components: • Two FRP tanks, • Two tank mixers, • Funnel educator, • Level control instruments, • Two metering pumps, • A calibration column, • Pushwater rotameter, and • In-line static mixer Volute Press Polymer System An emulsion polymer system is used with the volute press to increase sludge flocculation and enhance biosolids dewaterability. The system is compromised of a skid mounted polymer activation chamber, dilution water system, polymer feed pump, and controls. The polymer system is located in the chemical feed room of the Process Building where the sodium acetate system pumps were previously located. The pumps were removed for installation of the new emulsion polymer system. A summary of Chemical Systems equipment at the Kalispell AWWTP is presented in Table 4-20. Table 4-20. Chemical Systems Equipment Summary Equipment Description/Quantity Alum System Tank Quantity Storage Volume Pumps Quantity Horsepower, each Capacity, each 1 5,200 gallons 2 0.25 hp 26.9 gph DAFT Polymer System Tank Quantity Storage Volume, each Pumps Quantity Horsepower, each Capacity, each 2 350 gallons 2 0.75 hp 100 gph Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-56 Equipment Description/Quantity Belt Filter Press Polymer System Tank Quantity Storage Volume, each Pumps Quantity Horsepower, each Capacity, each 1 550 gallons 2 1.5 hp 190 gph Volute Press Polymer System Capacity 10 gpm Process and Equipment Assessment The chemical storage and feed equipment is performing as designed and is in fair condition. Capacity of the alum tank is anticipated to be exceeded during the planning period. City staff are preparing to receive totes of emulsion polymer instead of 55-gallon drums for the volute press polymer system. Modifications to the chemical room will be required to accommodate these changes. 4.3.19 Electrical and SCADA Systems The electrical and supervisory control and data acquisition (SCADA) systems at the facility are generally in good operating condition. Electrical services for the Influent Pumping Station and UV disinfection are each on a diesel generator for standby power, which meets the requirements of MDEQ Circular DEQ-2, Section 56.1 for emergency power for pumping and disinfection systems. City staff has expressed a preference to have a designated emergency standby power generator for the aeration blowers and a separate generator for the remaining major facility equipment. 4.3.20 Facility Staffing The Kalispell AWWTP is currently staffed with one plant manager, an assistant plant manager, an industrial pretreatment program director, one laboratory technician, and four operators. A staff organizational chart is shown in Figure 4-42. The facility is staffed eight hours per day with one of the operators on rotation each weekend. One operator is on call for the remaining time while the facility is not staff. The on-call operator is rotated weekly. The facility is also monitored by a Supervisory Control and Data Acquisition (SCADA) system. The system provides an alarm during the failure of critical equipment or processes. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-57 Figure 4-42. Kalispell AWWTP Org Chart 4.3.21 Administration and Laboratory Building The administration and laboratory facilities are located in the Control Building. The facilities include a laboratory, a conference room, the control room, two offices, an employee break room, restroom facilities, a changing room and shower facilities. The control room, which looks out over the bioreactors, can accommodate two to three operators and is furnished with several work stations. The laboratory is equipped with a fume hood, emergency eye wash and shower, BOD incubator, dishwasher and several sinks. There is also a work station/office in the laboratory. The conference room can seat approximately thirty people and is set up with audio visual equipment for meetings and continuing education. The laboratory facilities and administration building are shown in Figure 4-43 and Figure 4-44, respectively. Plant Manager Operators Assistant Plant Manager Pretreatment Program Laboratory Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-58 Figure 4-43. Laboratory Facilities Figure 4-44. Exterior of Administration Building Process and Equipment Assessment The administration and laboratory facilities were constructed as part of the 1990 BNR project. They are in generally in good condition. The facilities are adequate for current staff. At some point in the planning period, additional office space may need to be added to accommodate additional staff. The lab is equipped so that staff can perform all required testing with the exception of heavy metals and fish toxicity testing, which is contracted out. Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-59 4.4 Existing Facilities Survey A survey was sent to AWWTP staff to obtain input directly from the operations staff. Results were compiled and discussed during a workshop held with City staff and treatment plant operators on October 18, 2018. Survey results and a summary of the discussion held during the workshop are below. 4.4.1 Survey Item 1: Single Greatest Challenge at AWWTP The first survey question was “What is your single greatest challenge or concern at the treatment plant?” Results are presented in Figure 4-45. Future regulations was the greatest concern or challenge for staff members, followed by financial resources. Time management, faulty equipment, and meeting current permit limits all had an equal number of responses. Figure 4-45. Survey Item 1 Results 4.4.2 Survey Item 2: Prioritization of Work Related Subjects Survey Item No. 2 asked the operators to list the subjects below in order of importance. • Proper Tool(s) • Water Quality • Energy use/cost Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-60 • Chemical use/cost • Personal and co-worker safety • Public Health A graphical representation of the responses to this survey item is presented in Figure 4-46. Generally, personal and co-worker safety was very important to the operations staff. Public health and water quality, which are interrelated, were also important to staff. Proper tools, energy use/cost, and chemical use/cost were less important, comparatively. Figure 4-46. Survey Item 2 Results – Importance of Work Related Items 4.4.3 Survey Item 3: Treatment Process Functional Rating Survey Item 3 asked the operators to rate each treatment process within the facility. Results are presented in Figure 4-47. The areas scoring poorly are briefly discussed below. • Influent screening o Lack of mechanical screen redundancy o Difficulty obtaining parts for existing mechanical screen • Grit removal o Lack of equipment redundancy • Effluent filtration o Effluent filters are a hydraulic restriction at peak flows Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-61 • Fermenter o Challenges operating the process consistently Figure 4-47. Survey Item 3 Results - Treatment Processes Rating 4.4.4 Survey Item 4: Time Consuming Areas Survey Item 4 asked the operators to identify what building, process, or equipment they felt they spent the most operations and maintenance. Results are summarized as follows: • Fermenter: 3 responses • Primary digester: 3 responses • The laboratory: 2 responses (two laboratory technicians completed the survey) • Dewatering: 1 response • Blowers: 1 response • Bioreactor: 1 response Kalispell AWWTP 2018 Facility Plan Update Chapter 4 - Existing Wastewater Treatment Facility Page 4-62 4.4.5 Survey Item 5: Self-rating of Facility Survey Item 5 asked City staff to rate the Kalispell AWWTP compared to other wastewater treatment plants in Montana, out of five stars. One star being poor and five stars being excellent. The average rating was 4.7 stars. This reflects the positive lens through which the operators view and take pride in their facility. 4.4.6 Survey Item 6: Expenditure Choice The operators were asked what they would hypothetically spend $1,000,000 on at the Kalispell AWWTP. • Secondary Clarifiers: 5 responses • Equipment Replacement: 2 responses • Effluent Filtration: 2 responses • Belt Press: 1 response • Employee Salaries: 1 response • Blower Piping Modifications: 1 response • Channel Modifications: 1 response • Primary Digester Foam Mitigation: 1 response 4.5 Facility Evaluation Summary The following major process areas have been identified as requiring further evaluation to address capacity issues, aging equipment, equipment redundancy, modification to meet future regulations, and/or operations and maintenance requirements. Further evaluation is included in Chapter 5. • Preliminary Treatment • Influent Pumping Station • Primary Clarification • Flow Equalization Basin • Secondary Treatment • Secondary Clarification • Effluent Filtration • Reaeration Basin • Anaerobic Digestion • Sludge Thickening • Biosolids Disposal CHAPTER 5 WASTEWATER TREATMENT FACILITY IMPROVEMENT ALTERNATIVES AND EVALUATIONS Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page i Contents 5 Wastewater Treatment Facility Improvement Alternatives and Evaluation ...................................... 5-1 5.1 Introduction ............................................................................................................................. 5-1 5.2 Evaluation Process ................................................................................................................. 5-1 5.2.1 Define Process Methodology and Evaluation Criteria ............................................... 5-1 5.2.2 Brainstorm and Screen Ideas .................................................................................... 5-1 5.2.3 Alternatives Development and Evaluation ................................................................ 5-1 5.2.4 Alternatives Selection ................................................................................................ 5-2 5.3 Basis for Cost Estimates ........................................................................................................ 5-2 5.3.1 Level of Accuracy ...................................................................................................... 5-3 5.3.2 Construction Cost Index ............................................................................................ 5-4 5.3.3 Planning Period ......................................................................................................... 5-4 5.3.4 Land........................................................................................................................... 5-4 5.3.5 Contingencies ............................................................................................................ 5-4 5.4 Influent Screening (INS) Alternatives ..................................................................................... 5-4 5.4.1 Alternative INS 1: No Action ..................................................................................... 5-4 5.4.2 Alternative INS 2: New FSM Screen ........................................................................ 5-5 5.4.3 Alternative INS 3: New Alternative Manufacturer Screens ...................................... 5-5 5.4.4 Alternative Costs ....................................................................................................... 5-5 5.4.5 Recommended Alternative ........................................................................................ 5-5 5.5 Influent Pumping Station (INP) Alternatives ........................................................................... 5-6 5.5.1 Alternative INP 1: No Action ...................................................................................... 5-6 5.5.2 Alternative INP 2: Replace 2 Existing Pumps with New Higher Capacity Pumps ....................................................................................................................... 5-7 5.5.3 Alternative INP 3: Install 3 New Pumps in New Dry Pit ............................................ 5-7 5.5.4 Alternative Costs ....................................................................................................... 5-9 5.5.5 Recommended Alternative ...................................................................................... 5-10 5.6 Primary Clarification (PCL) Alternatives ............................................................................... 5-10 5.6.1 Alternative PCL 1: No Action ................................................................................... 5-10 5.6.2 Alternative PCL 2: Single, 115-FT Diameter Primary Clarifier ................................ 5-11 5.6.3 Alternative PCL 3: Two, 75-FT Diameter Primary Clarifiers ................................... 5-11 5.6.4 Alternative Costs ..................................................................................................... 5-12 5.6.5 Recommended Alternative ...................................................................................... 5-12 5.7 Flow Equalization Basin (EQB) Alternatives ........................................................................ 5-14 5.7.1 Alternative EQB 1: No Action .................................................................................. 5-14 5.7.2 Alternative EQB 2: Construct New EQ Basin/Future Primary Clarifier ................... 5-14 5.7.3 Alternative EQB 3: Modify Existing EQ Basin ......................................................... 5-14 5.7.4 Alternative EQB 4: Modify Existing Primary Clarifiers to Expand EQ Volume ........ 5-15 5.7.5 Alternative Costs ..................................................................................................... 5-15 5.7.6 Recommended Alternative ...................................................................................... 5-15 5.8 Secondary Treatment (SCT) Alternatives ............................................................................ 5-16 5.8.1 Alternative SCT 1: No Action .................................................................................. 5-17 5.8.2 Alternative SCT 2: Conversion to a 5-stage process .............................................. 5-17 5.8.3 Alternative SCT 3: Integrated Fixed-Film Activated Sludge (IFAS) ........................ 5-18 5.8.4 Alternative SCT 4: Membrane Bioreactor (MBR) .................................................... 5-19 5.8.5 Alternative SCT 5: Granular Activated Sludge (GrAS) ............................................ 5-22 5.8.6 Alternative Costs ..................................................................................................... 5-24 5.8.7 Recommended Alternative ...................................................................................... 5-24 5.9 Secondary Clarification (SCL) Alternatives .......................................................................... 5-25 5.9.1 Alternative SCL 1: No Action ................................................................................... 5-26 5.9.2 Alternative SCL 2: Install Launder Covers .............................................................. 5-26 Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page ii 5.9.3 Alternative SCL 3: Install Flat Clarifier Covers ........................................................ 5-26 5.9.4 Alternative SCL 4: Install Dome Clarifier Covers .................................................... 5-27 5.9.5 Alternative Costs ..................................................................................................... 5-28 5.9.6 Recommended Alternative ...................................................................................... 5-29 5.10 Effluent Filtration (EFF) Alternatives .................................................................................... 5-30 5.10.1 Alternative EFF 1: No Action ................................................................................... 5-30 5.10.2 Alternative EFF 2: Tertiary Membrane Filtration (TMF) .......................................... 5-31 5.10.3 Alternative EFF 3: Effluent Management ................................................................ 5-32 5.10.4 Alternative Costs ..................................................................................................... 5-34 5.10.5 Recommended Alternative ...................................................................................... 5-34 5.11 Reaeration Basin (RAB) Alternatives ................................................................................... 5-35 5.11.1 RAB 1: No Action .................................................................................................... 5-35 5.11.2 RAB 2: Reaeration Basin Modifications .................................................................. 5-35 5.11.3 RAB 3: Relocation of Reaeration Basin .................................................................. 5-36 5.11.4 Alternative Costs ..................................................................................................... 5-36 5.11.5 Recommended Alternative ...................................................................................... 5-36 5.12 Anaerobic Digestion (AND) Alternatives .............................................................................. 5-37 5.12.1 Alternative AND 1: No Action .................................................................................. 5-37 5.12.2 Alternative AND 2: Second Heat Exchanger and New Recirculation Pumps ......... 5-37 5.12.3 Alternative AND 3: Second Primary Digester ......................................................... 5-38 5.12.4 Alternative Costs ..................................................................................................... 5-38 5.12.5 Recommended Alternative ...................................................................................... 5-38 5.13 Sludge Thickening (STK) Alternatives ................................................................................. 5-39 5.13.1 Alternative STK 1: No Action ................................................................................... 5-40 5.13.2 Alternative STK 2: New DAFT System .................................................................... 5-40 5.13.3 Alternative STK 3: Gravity Belt Thickener (GBT) .................................................... 5-43 5.13.4 Alternative STK 4: Disc Thickener .......................................................................... 5-44 5.13.5 Alternative STK 5: Rotary Drum Thickener (RDT) .................................................. 5-45 5.13.6 Alternative STK 6: Screw Press .............................................................................. 5-46 5.13.7 Alternative STK 7: Volute Thickener ....................................................................... 5-47 5.13.8 Alternative STK 8: Centrifuge .................................................................................. 5-48 5.13.9 Sludge Thickening Alternatives Comparison .......................................................... 5-49 5.13.10 Alternative Costs ..................................................................................................... 5-54 5.13.11 Recommended Alternative ...................................................................................... 5-55 5.14 Biosolids Dewatering/Disposal (BDD) Alternatives .............................................................. 5-56 5.14.1 Alternative BDD 1: No Action .................................................................................. 5-56 5.14.2 Alternative BDD 2: Composting Facility .................................................................. 5-56 5.14.3 Alternative BDD 3: Class A Biosolids Dewatering Equipment ................................ 5-57 5.14.4 Alternative Costs ..................................................................................................... 5-57 5.14.5 Recommended Alternative ...................................................................................... 5-57 5.15 Miscellaneous Improvements ............................................................................................... 5-58 5.15.1 Aeration Blower Evaluation Study ........................................................................... 5-58 5.15.2 Sidestream Treatment ............................................................................................. 5-59 5.15.3 Biofilter Bed Rehabilitation ...................................................................................... 5-59 5.15.4 Chemical Room Modifications ................................................................................. 5-59 5.15.5 Standby Power for Aeration Blowers and Critical Facility Equipment ..................... 5-59 5.15.6 Administration/Laboratory Building Expansion ....................................................... 5-59 5.15.7 Digester Chemical Feed System ............................................................................. 5-59 5.15.8 Fermenter & VFA Pipeline Condition Assessment ................................................. 5-59 5.15.9 Effluent Management Plan ...................................................................................... 5-59 5.15.10 Replace Belt Filter Press ......................................................................................... 5-60 5.15.11 Effluent Temperature Mitigation Plan ...................................................................... 5-60 5.15.12 Influent Piping and Diversion Structure Rehabilitation ............................................ 5-60 5.16 Recommended Wastewater Treatment Facility Improvements ........................................... 5-60 Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page iii Tables Table 5-1. Alternatives Evaluation Criteria ................................................................................................. 5-2 Table 5-2. Influent Screening Alternative Costs......................................................................................... 5-5 Table 5-3. Influent Screening Alternatives Scoring .................................................................................... 5-6 Table 5-4. Influent Pumping Station Alternative Costs .............................................................................. 5-9 Table 5-5. Influent Pumping Station Alternatives Scoring ....................................................................... 5-10 Table 5-6. Primary Clarification Alternative Costs ................................................................................... 5-12 Table 5-7. Primary Clarification Alternatives Scoring .............................................................................. 5-13 Table 5-8. Equalization Basin Alternative Costs ...................................................................................... 5-15 Table 5-9. EQ Basin Alternatives Scoring ................................................................................................ 5-16 Table 5-10. Future Equivalent Nutrient Concentrations ........................................................................... 5-17 Table 5-11. Secondary Treatment Alternative Costs ............................................................................... 5-24 Table 5-12. Secondary Treatment Alternatives Scoring .......................................................................... 5-24 Table 5-13. Secondary Clarification Alternative Costs ............................................................................ 5-29 Table 5-14. Secondary Clarification Alternatives Scoring ........................................................................ 5-30 Table 5-15. Effluent Filtration Alternative Costs....................................................................................... 5-34 Table 5-16. Effluent Filtration Alternatives Scoring .................................................................................. 5-35 Table 5-17. Reaeration Basin Alternative Costs ...................................................................................... 5-36 Table 5-18. Effluent Filtration Alternatives Scoring .................................................................................. 5-37 Table 5-19. Anaerobic Digestion Alternative Costs ................................................................................. 5-38 Table 5-20. Anaerobic Digestion Equipment Alternatives Scoring .......................................................... 5-39 Table 5-21. Anaerobic Digestion Primary Digester Alternatives Scoring ................................................ 5-39 Table 5-22. Air-aspirating Pump System and Conventional Pressurization System Comparison .......... 5-43 Table 5-23. Sludge Thickening Energy Consumption Comparison ......................................................... 5-50 Table 5-24. Sludge Thickening Polymer Consumption Comparison ....................................................... 5-50 Table 5-25. Sludge Thickening Water Consumption Comparison ........................................................... 5-51 Table 5-26. Sludge Thickening Unattended Operation Comparison ....................................................... 5-52 Table 5-27. Sludge Thickening Alternatives Comparison ........................................................................ 5-54 Table 5-28. Sludge Thickening Alternative Costs .................................................................................... 5-55 Table 5-29. Sludge Thickening Alternatives Scoring ............................................................................... 5-56 Table 5-30. Biosolids Dewatering/Disposal Alternatives Costs ............................................................... 5-57 Table 5-31. Biosolids Dewatering/Disposal Alternatives Scoring ............................................................ 5-58 Table 5-32. Miscellaneous Improvements Cost Summary ...................................................................... 5-60 Figures Figure 5-1. AACE Cost Estimate Classification System ............................................................................ 5-3 Figure 5-2. Floodplain Map for Kalispell AWWTP...................................................................................... 5-9 Figure 5-3. Primary Clarifier Layout ......................................................................................................... 5-11 Figure 5-4. 5-stage Bardenpho Process Schematic ................................................................................ 5-18 Figure 5-5. IFAS Media Depiction ............................................................................................................ 5-19 Figure 5-6. MBR Flow Schematic for Nitrogen and Phosphorous Removal ............................................ 5-21 Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page iv Figure 5-7. Commercial GrAS Product .................................................................................................... 5-23 Figure 5-8. Example Launder Cover ........................................................................................................ 5-26 Figure 5-9. Example Flat Clarifier Cover .................................................................................................. 5-27 Figure 5-10. Example Dome Clarifier Cover ............................................................................................ 5-28 Figure 5-11. TMF Flow Schematic ........................................................................................................... 5-32 Figure 5-12. Typical Liquid – Gas Mixing Centrifugal Pump .................................................................... 5-41 Figure 5-13. Typical Air-aspirating Micro-Bubble Generator ................................................................... 5-41 Figure 5-14. DAFT Unit with Air-aspirating Pump System ....................................................................... 5-42 Figure 5-15. Example Gravity Belt Thickener .......................................................................................... 5-44 Figure 5-16. Huber Twin Disc Thickener ................................................................................................. 5-45 Figure 5-17. Parkson Rotary Drum Thickener ......................................................................................... 5-46 Figure 5-18. Huber Screw Press Thickener ............................................................................................. 5-46 Figure 5-19. PW Tech Volute Thickener .................................................................................................. 5-48 Figure 5-20. Centrisys Centrifuge Thickener ........................................................................................... 5-49 Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-1 5 Wastewater Treatment Facility Improvement Alternatives and Evaluation 5.1 Introduction This chapter evaluates potential AWWTP improvement alternatives for areas of the facility identified in Chapter 4. Each alternative includes a description of the alternative, estimated construction cost, and evaluation criteria score. A recommended alternative is selected based on evaluation scoring. 5.2 Evaluation Process An evaluation methodology was agreed upon through an interactive process involving both the City and the HDR project team. Major elements of the process are described below. 5.2.1 Define Process Methodology and Evaluation Criteria To provide a consistent planning basis, a methodology was developed for the wastewater facility alternatives evaluation. This process defined evaluation criteria, outlined the decision-making process, and prescribed cost estimating procedures. The evaluation criteria are listed in Table 5-1. Each evaluation criteria were weighted equally and assigned a numerical score, with a possible score of 1 – 3 for each criteria and a total maximum score of 24 for each alternative. The higher the score, the more favorable the alternative. 5.2.2 Brainstorm and Screen Ideas Several workshops were held with City staff to discuss potential process enhancements and identify alternatives for improving the Kalispell AWWTP. Through the process, ideas that were fatally flawed, technically unproven, excessively expensive, or otherwise unworthy of detailed evaluation were eliminated. 5.2.3 Alternatives Development and Evaluation Alternatives surviving the initial screening discussions are further developed in this chapter. Preliminary sizing and cost estimating are conducted for both liquid stream and solids stream alternatives. Alternatives are compared based on cost and non-economic criteria listed in Table 5-1. Based on this analysis, recommendations for facility improvements are made. Unless otherwise stated, each alternative evaluated can be assumed to have a minimum design criteria for the 20 year planning period. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-2 Table 5-1. Alternatives Evaluation Criteria Evaluation Criteria Description Construction Cost • Estimated construction cost of the alternative Future Flexibility • Allows for potential future MPDES requirements • Allows for future growth O&M Requirements • Low complexity • Operational ease • Ease of automation • Reasonable maintenance • Reliability • Longevity • Compatible with existing facilities • Safe/low use of hazardous chemicals • Availability and lead time for delivery of parts Implementation • Ability to logically phase expansion • Ease of construction • Ability to maintain operation during construction • Minimal permit requirements • Ability to fit on site • Compatibility with surrounding land uses Operational History • Technology or equipment has a proven performance history at other similar facilities • Meets current MPDES requirements City Staff Preference • Considers City staff preference for certain technologies, equipment, manufacturers, etc. Sustainability • Vehicular traffic • Hazardous chemicals • Public safety • Air quality impacts (non-odor) Noise or Odor Potential • Malodorous odor potential • Nuisance noise potential • Vector attraction potential 5.2.4 Alternatives Selection The initial evaluation of alternatives is presented in subsequent sections of this chapter. Based on the results of the evaluation process, and incorporating comments received during City reviews, final alternatives and recommendations for consideration by the City are presented in Chapter 6. 5.3 Basis for Cost Estimates The proposed economic analysis is conducted using construction costs reported in late- 2018 dollars. The size of support buildings (if required) are selected based on similar- sized designs, and current similar building prices per square foot are applied to the floor space requirements. The cost of electrical and instrumentation and control, yard piping, site work, bond, insurance, mobilization, painting, and coatings is estimated by applying Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-3 percentages of the construction subtotal of the process unit costs. The percentages are based on HDR’s experience and knowledge of the costs of these items on similar wastewater treatment plant projects. Total construction costs include contractor markups and profit and appropriate contingency. Actual construction costs will depend on a variety of factors such as the final project scope and market conditions at the time of project bidding. Detailed cost estimates are included in Appendix B. 5.3.1 Level of Accuracy All project costs will be derived using the same level of estimating accuracy and, therefore, will be comparable. Actual construction costs may differ from the estimates presented, depending on specific design requirements and the economic climate at the time a project is bid. The level of detail used in the development of cost estimates in this facility plan is approximately 10 percent. This corresponds with a typical Class 4 estimate (Figure 5-1). An estimate of this type is normally expected to be within –15 to +50 percent of the actual construction cost. The final cost of the projects will depend on actual labor and materials costs, actual site conditions, productivity, competitive market conditions, bid dates, seasonal fluctuations, final project scope, final project schedule, and other variables. As a result, the final project costs will vary from the estimates presented in this report. The range of accuracy for a Class 4 cost estimate is broad, but these are typical levels of accuracy for planning work and they apply equally to all alternatives so that the relative estimated costs of the alternatives are comparable and can be used for sound decision-making. It is important to communicate this level of accuracy to policymakers and decision-makers. Figure 5-1. AACE Cost Estimate Classification System Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-4 5.3.2 Construction Cost Index Cost estimates will be obtained from projects in different locations and in different years. In order to bring all costs to a common, comparable base, the Engineering News Record (ENR) Construction Cost Index (CCI) is used. This is a common, industry accepted means for adjusting costs from different time periods and locations. The ENR CCI tracks construction costs in 22 U.S. cities and is computed from construction, materials, and labor costs. For this project, adjustments to costs will be made with the ENR 20 Cities Average CCI. The ENR CCI for December 2018 is 11,185.51. 5.3.3 Planning Period As stated in Chapter 3 – Basis of Planning, the Kalispell AWWTP Facility Plan Update includes developing a plan that will provide wastewater treatment services at least through 2038, i.e., a 20-year planning period. A key planning aspect is to consider potential future regulatory changes in development and selection of improvements. When sizing and siting treatment facilities, the ultimate planning period is also used to consider whether adequate space is available for expanding treatment facilities to meet ultimate capacity needs. 5.3.4 Land Land acquisition for all alternatives considered has not been included. It is assumed all improvements considered would need to occur within property already held by the City of Kalispell at no additional capital cost. 5.3.5 Contingencies Budgetary studies represent a rough level of construction cost estimating. To account for unknowns, construction cost estimates of the alternatives considered include a contingency factor of 25 percent. 5.4 Influent Screening (INS) Alternatives The single mechanical influent screen is a source of maintenance issues due to long lead times for parts. Alternatives considered for Influent Screening are as follows: Alternative INS 1: No Action Alternative INS 2: New FSM Screen Alternative INS 3: New Alternative Manufacturer Screens 5.4.1 Alternative INS 1: No Action Alternative INS 1 consists of making no improvements to the existing influent screens. The result of this alternative is that the existing perforated plate screen would continue to be a maintenance issue and frequent bypass of the mechanically cleaned screen to the bypass channel and manually cleaned screen. This would require frequent monitoring and cleaning of the manual bypass screen. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-5 5.4.2 Alternative INS 2: New FSM Screen Alternative INS 2 consists of replacing the existing manual screen in the bypass channel with a new FSM perforated plate screen. The existing mechanical screen is manufactured by FSM, so this alternative would provide equipment commonality among the screening and washer/compactor equipment. Installing a second FSM screen would offer a level of maintenance familiarity to staff and common spare parts for both screens. Operations staff time for monitoring of the influent screens will be reduced and protection of downstream equipment will be enhanced with more continuous debris removal. This alternative would provide capacity for projected 2038 peak flows. 5.4.3 Alternative INS 3: New Alternative Manufacturer Screens Alternative INS 3 consists of replacing and upgrading the existing equipment in both the main and bypass channels. Specific design components of this alternative include: • Removal of manually cleaned bar screen • Removal of mechanically cleaned FSM screen • Installation of two new mechanically cleaned screens with washer compactors Similar to INS 2, this alternative provides capacity for projected 2038 peak flows to pass through a mechanically cleaned screen. Operator maintenance activities with the influent screening process would be reduced. This alternative would also mitigate the customer service issues with the existing screen manufacturer. Two identical sets of equipment would provide redundancy and simplify ordering spares parts. 5.4.4 Alternative Costs Table 5-2 presents costs for Influent Screening Alternatives INS 2 and INS 3. Table 5-2. Influent Screening Alternative Costs Alternative Construction Cost Estimate 1,2 INS 2: New FSM Screen $ 755,000 INS 3: New Alternative Manufacturer Screens $ 1,234,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.4.5 Recommended Alternative Table 5-3 presents scoring for the Influent Screening Alternatives. Alternative INS 1 does not provide the necessary improvements to influent screening and will not be investigated further. A consideration for Alternative INS 2 is customer service provided by the existing screen manufacturer. Kalispell AWWTP staff have mentioned long lead Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-6 times and difficulty ordering parts, leading to long equipment down time and less efficient debris removal from the influent raw sewage. Alternative INS 3 is the most expensive of the alternatives evaluated but would improve operational efficiency for preliminary treatment that supports the entire treatment process. The recommended alternative is INS 3, install two new alternative manufacture perforated plate screens to replacing the existing perforated plate screen and manual bar screen. The existing 10 mm perforated plate screen panel is being replaced with an 8- mm diameter perforation panel. Because of the investment into the existing screen, the timing for implementation of this alternative will be postponed several years. Implementation of this alternative should also be considered in conjunction with installation of membrane technology which requires fine screens. See discussion in Section 5.8.4 and Section 5.10.2. Table 5-3. Influent Screening Alternatives Scoring Evaluation Criteria INS 1 INS 2 INS 3 Construction Cost 3 2 1 Future Flexibility 1 2 3 O&M Requirements 1 2 3 Implementation 3 2 1 Operational History 1 1 3 City Staff Preference 1 2 3 Sustainability 1 2 3 Noise or Odor Potential 1 2 2 Total 12 15 19 5.5 Influent Pumping Station (INP) Alternatives The firm capacity of the Influent Pumping Station is not sufficient for the planning horizon. Alternatives considered for the Influent Pumping Station are as follows: Alternative INP 1: No Action Alternative INP 2: Replace 2 Existing Pumps with New Higher Capacity Pumps Alternative INP 3: Existing Pumps Remain, Install 3 New Pumps in New Dry Pit 5.5.1 Alternative INP 1: No Action Alternative INP 1 consists of not making any improvements to the existing pumping station. The result of this alternative is that the station will lack capacity to handle projected peak hour flows during the planning period. The firm capacity of the station Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-7 with five pumps running is 9,630 gpm (13.9 MGD). The projected peak hour flow for 2038 is 9,850 gpm (14.2 MGD). While this capacity is adequate to handle peak hourly flows in the near term, capacity will have to be increased. The no action alternative could result in the influent pumping station wet well being overtopped resulting in raw sewage being spilled and a possible MDEQ permit violation. Selection of this alternative is not practical and will not be developed further. 5.5.2 Alternative INP 2: Replace 2 Existing Pumps with New Higher Capacity Pumps Alternative INP 2 involves the replacement of two existing pumps with new, higher capacity pumps sized to meet the 2038 peak hour flows. Specific design components of this alternative include the following: • Removal of two existing variable speed lift pumps, valves, and controls • Installation of two new variable speed pumps, valves, and controls • Modifications to wet well ventilation for code compliance The use of six, variable speed pumps matches the existing configuration of the lift station. Five of the six existing pumps have been in use for 26 years, and maintenance activities with the pumps will become more frequent. The two new variable speed pumps, along with the four existing pumps, would provide a firm capacity adequate for the year 2038. This alternative makes use of the existing 10-inch pump discharge piping, the 18-inch header piping inside the pumping station and the 30-inch buried pipe between the pumping station and the Primary Clarifiers. A pump evaluation was completed in Section 5.5 of the 2005 Basis of Design Report that found that a Gorman-Rupp T-10 pump with a continuous vane impeller could provide up to 2,800 gpm. A minimum flow rate of 1,970 gpm per pump is required to satisfy the design firm capacity. Full implementation of this alternative would be required by 2035 and could be accomplished in phases. Benefits of Alternative INP 2 include: • The new pumps increase capacity to 2038 peak hour flows, without replacing all pumps • The variable speed maintains existing configuration • Installation of the new pumps can be phased as needed to increase capacity and replace aging pumps 5.5.3 Alternative INP 3: Install 3 New Pumps in New Dry Pit Alternative INP 3 maintains the existing pumps in the lift station and involves installation of three new submersible pumps in a dry pit on the north side of the existing wet well. Suction lines from each pump would combine to a common manifold and a single buried suction line would be cut into the wet well of the existing lift station. The alternative also includes a modification of the existing wet well ventilation to bring it into compliance with building code requirements. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-8 The new pumps would be sized to handle the difference between the firm capacity of the existing lift station and the 2053 design peak hour flow of 16.8 MGD, or approximately 2.9 MGD. Year 2053 is chosen for a design flow as it would be approximately 20 years after the year of implementation. It is assumed that two duty pumps and one standby pump would be installed in the new vault. This alternative also assumes that at least one of the three new pumps would have a variable speed drive. There are several considerations associated with this alternative that differentiate it from the other influent pumping station alternatives. One consideration is that the suction line between the new vault and the existing wet well may be difficult to construct. The existing lift station was constructed on top of a clarifier that was abandoned as part of the 1992 upgrades. Sloped sides were constructed inside the bottom of the clarifier to create the wet well and the pumps were installed on a concrete slab poured on top of the clarifier. The sloped walls of the wet well are believed to be up to 11 feet thick, making core drilling for the new suction line difficult and expensive. Another consideration would be limiting excavation in the proximity of the old clarifier walls to minimize disturbance of the lift station wet well. Other advantages and disadvantages would be: • Advantages: o New pumps increase capacity to 2053 peak hour flows without replacing existing pumps o Maintains combination of constant speed and variable speed for flexibility o Pumps could be installed in phases • Disadvantages: o Increases number of pumps and types of pumps to maintain o Pumps installed in a vault making them less accessible; could be confined space issues o Constructability concerns with installation of suction lines o Construction would involve taking the pumping station out of service and draining the wet well to core drill and make modifications. o Most expensive alternative Construction of a new dry pit would take place in a Special Flood Hazard Area (Figure 5-2). Before work could commence, a Conditional Letter of Map Revision would need to be submitted to the Federal Emergency Management Agency (FEMA). A hydraulic analysis will need to be performed and the flood plain map possibly revised. Once construction is completed, a Letter of Map Revision must be submitted to FEMA. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-9 Source: FEMA Flood Map Service Center Figure 5-2. Floodplain Map for Kalispell AWWTP 5.5.4 Alternative Costs Table 5-4 presents costs for Influent Pumping Station Alternatives INP 2 and INP 3. Table 5-4. Influent Pumping Station Alternative Costs Alternative Construction Cost Estimate 1,2 INP 2: Replace 2 Existing Pumps with New Higher Capacity Pumps $ 268,000 INP 3: Install 3 New Pumps in New Vault $ 1,063,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. Influent PumpingStation Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-10 5.5.5 Recommended Alternative Table 5-5 presents scoring for the Influent Pumping Station Alternatives. Given the complex constructability issues and accompanying high costs for Alternative INP 3, Alternative INP 2 is recommended. Installation of higher capacity pumps would provide sufficient pumping capacity for the foreseeable future. Table 5-5. Influent Pumping Station Alternatives Scoring Evaluation Criteria INP 2 INP 3 Construction Cost 2 1 Future Flexibility 2 1 O&M Requirements 2 1 Implementation 2 1 Operational History 2 3 City Staff Preference 2 2 Sustainability 2 2 Noise or Odor Potential 3 3 Total 17 14 5.6 Primary Clarification (PCL) Alternatives The existing primary clarifier capacity is projected to be exceeded by the year 2033. The existing rectangular primary clarifier technology requires a high level of maintenance, so it will not be evaluated here. Primary clarification alternatives must be considered concurrently with the equalization basin alternatives described in Section 5.7. Alternatives considered for Primary Clarification are as follows: Alternative PCL 1: No Action Alternative PCL 2: Construct a Single, 115-FT Diameter Primary Clarifier Alternative PCL 3: Construct Two, 75-FT Diameter Primary Clarifiers 5.6.1 Alternative PCL 1: No Action Alternative PCL 1 consists of making no improvements to the existing primary clarifiers. Routine maintenance of existing mechanical equipment would continue. Primary clarification capacity would be exceeded during the planning resulting in decreased primary effluent water quality. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-11 5.6.2 Alternative PCL 2: Single, 115-FT Diameter Primary Clarifier Alternative PCL 2 consists of constructing a single, 115-FT diameter clarifier with a water depth of approximately 12 FT. The proposed clarifier has been sized to handle projected 2043 flows. A new building to house sludge and scum pumps is also included in this alternative. 5.6.3 Alternative PCL 3: Two, 75-FT Diameter Primary Clarifiers Alternative PCL 3 consists of constructing two 75-FT diameter primary clarifiers with a sidewater depth of 12 FT. A new building to house sludge and scum pumps is also included in this alternative. The new clarifiers would be constructed south of the existing primary clarifiers and east of the biofilter beds. Extrapolating current projected flows, the two new primary clarifiers would have capacity to approximately 2065. Additional land area would still be available to build a third 75-FT diameter primary clarifier in the future to serve the facility in the future (Figure 5-3). Three 75-FT diameter primary clarifiers would have capacity for a total estimated peak hour flow of approximately 19.7 MGD. Figure 5-3. Primary Clarifier Layout This alternative also considered four 60-FT diameter clarifiers for full buildout conditions. The clarifiers would have an estimated sidewater depth of 12 FT. Four 60-FT diameter clarifiers would have capacity for a total estimated peak hour flow of approximately 16 MGD, compared to 19.7 MGD for three 75-FT diameter clarifiers. The 75-FT diameter clarifiers where chosen for further evaluation. A phased approach to this alternative is considered whereby a 75-FT diameter tank would be constructed in 2020 to initially provide additional equalization basin volume, see also Alternative EQB 2 in Section 5.7.2 below. In 2030, a second 75-FT diameter Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-12 clarifier would be constructed, the existing 75-FT diameter tank would be converted to a primary clarifier, and the existing rectangular primary clarifiers would be converted to equalization capacity. The first 75-FT diameter tank would have piping which would hydraulically connect it to the existing EQ basin. The piping would be isolated or disconnected when the tank is converted to a primary clarifier. The tank would also have automatic spray water for odor mitigation. 5.6.4 Alternative Costs Table 5-6 presents costs for Primary Clarification Alternatives PLC 2 and PLC 3. Both alternatives include costs for a new primary sludge and scum pumping building. Costs for Alternative PCL 3 reflects conversion of the first 75-FT diameter tank to primary clarification and construction of the second 75-FT diameter primary clarifier. Costs for the construction of the first 75-FT diameter tank are included in Alternative EQB 2. Table 5-6. Primary Clarification Alternative Costs Alternative Construction Cost Estimate 1,2 PCL 2: Single, 115-FT Diameter Primary Clarifier & Control Building $ 4,451,000 PCL 3: Two, 75-FT Diameter Primary Clarifiers & Control Building $ 4,374,0003 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 3. Costs for construction of one 75-FT diameter structure are included in Alternative EQB 2. The construction costs here include conversion of that structure to a clarifier and construction of a new primary clarifier. 5.6.5 Recommended Alternative Table 5-7 presents scoring for the Primary Clarification alternatives. Although the cost and implementation strategy for the no action alternative score high, the result would be degradation of effluent water quality from the clarifiers, particularly during peak flow events. While some short-term degradation in primary effluent quality can be mitigated by subsequent treatment systems, process performance cannot be guaranteed while stressing those systems. This alternative is not recommended due to projected flows within the planning period. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-13 Table 5-7. Primary Clarification Alternatives Scoring Evaluation Criteria PCL 1 PCL 2 PCL 3 Construction Cost 3 2 1 Future Flexibility 2 1 2 O&M Requirements 2 3 1 Implementation 3 2 1 Operational History 1 2 3 City Staff Preference 1 1 3 Sustainability 1 2 3 Noise or Odor Potential 2 2 2 Total 15 15 16 Considerations for Alternatives PCL 2 and PCL 3 are flexibility with primary clarification, redundancy, and available land. Having only one clarifier would create an issue when clarifier maintenance is required or during equipment failure. If a primary clarifier mechanism component fails, for example, then facility performance could be hindered while equipment replacement or repair work occurs. Alternative PCL 2 leaves little operational flexibility or room for future expansion of the facility. Because the existing clarifiers have sufficient capacity to 2033, there is time to phase construction of new clarifiers. However, as discussed in Chapter 4, additional equalization volume is required sooner. Alternative PCL 3 requires selection of Alternative EQB 2. Sequencing would be as follows: • Year 2020 o Construct one, 75-FT diameter tank to be used as EQ volume. The new tank would be hydraulically connected to the existing EQ basin. See Alternative EQB 2 in Section 5.7.2. • Year 2030 o Convert the existing 75-FT diameter tank to a primary clarifier. o Construct the second 75-FT diameter clarifier. o Construct a new primary sludge and scum pumping building. o Convert existing rectangular primary clarifiers to equalization volume. Because of the flexibility offered by Alternative PCL 3, and the phased approach to address near-term EQ volume capacity issues and short-term primary clarification capacity issues, Alternative PCL 3 is recommended. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-14 5.7 Flow Equalization Basin (EQB) Alternatives Additional equalization volume is required to provide operators the ability to continue consistent facility performance. As mentioned in Section 5.6, modifications to the EQ basin must be considered concurrently with Primary Clarification alternatives. Alternatives considered for the EQ Basin are as follows: Alternative EQB 1: No Action Alternative EQB 2: Construct New EQ Basin/Future Primary Clarifier Alternative EQB 3: Modify Existing EQ Basin Alternative EQB 4: Modify Existing Primary Clarifiers to Expand EQ Volume 5.7.1 Alternative EQB 1: No Action Alternative EQB 1 consists of not making any modifications to the existing equalization basin. Routine maintenance of existing components would continue. 5.7.2 Alternative EQB 2: Construct New EQ Basin/Future Primary Clarifier Alternative EQB 2 was discussed briefly with Alternative PCL 3 in Section 5.6.3. This alternative proposes to construct one 75-FT diameter tank in 2020. The existing EQ storage volume has a deficiency of 240,000 gallons needed for 2038 average flows. One 75-FT diameter tank with 12 FT sidewater depth provides 395,000 gallons of additional equalization basin storage. Total EQ basin volume would be 770,000 gallons. Design of the 75-FT diameter EQ tank will include considerations for future conversion to a primary clarifier, anticipated for the year 2030. Once the 75-FT diameter tank is converted to primary clarification, the existing rectangular clarifiers can be modified for additional equalization basin capacity, see Alternative EQB 4. 5.7.3 Alternative EQB 3: Modify Existing EQ Basin Alternative EQB 3 analyzed making modifications to the existing EQ basin to provide additional EQ volume. To provide an additional 240,000 gallons of EQ volume the water surface elevation would need to be raised approximately seven feet. This alternative includes raising the walls of the existing equalization basin and pumping into the basin. Modifications to the metal walkways and handrails, wash down equipment, gates, and weir would be required. Lowering the bottom slab of the EQ basin was considered as a part of this alternative. The slab would be demolished and a new, sloped slab poured to the match the bottom of the effluent basin sump. Due to the unknown geotechnical and groundwater conditions, and the accompanying risks and construction costs, these modifications were not developed further. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-15 5.7.4 Alternative EQB 4: Modify Existing Primary Clarifiers to Expand EQ Volume Alternative EQB 4 involves modifying the existing rectangular clarifiers to expand the capacity of the adjacent EQ basin. The common wall between the clarifiers and EQ basin would be removed and clarifier mechanism components would also be removed. Each existing primary clarifiers has an effective volume of approximately 165,000 gallons. Converting both clarifiers would add 330,000 gallons to the equalization basin storage, for a total EQ capacity of 705,000 gallons. This alternative requires Alternatives PCL 2 or PCL 3 to be implemented as existing primary clarification is removed with this option. 5.7.5 Alternative Costs Table 5-8 presents costs for EQ Basin Alternatives EQB 2, EQB 3, and EQB 4. Table 5-8. Equalization Basin Alternative Costs Alternative Construction Cost Estimate 1,2 EQB 2: Construct New EQ Basin/Future Primary Clarifier $ 1,845,0003 EQB 3: Modify Existing EQ Basin $ 505,000 EQB 4: Modify Existing Primary Clarifiers to Expand EQ Volume $ 451,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 3. Includes costs to construct the structure which will be converted to a primary clarifier in the future. 5.7.6 Recommended Alternative Table 5-9 presents scoring for the EQ Basin alternatives. Alternatives EQB 2 and EQB 4 have the highest total scores. The recommendation is to implement EQB 2 in 2020 and EQB 4 in 2030. To meet the requirements of MDEQ Circular DEQ-2, Section 65.51, two submersible mixers would be installed in the 75-FT diameter tank to provide mixing. The mixers would be relocated to the expanded, rectangular EQ basin in 2030. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-16 Table 5-9. EQ Basin Alternatives Scoring Evaluation Criteria EQB 1 EQB 2 EQB 3 EQB 4 Construction Cost 3 1 2 2 Future Flexibility 2 3 2 2 O&M Requirements 1 2 2 3 Implementation 3 2 1 2 Operational History 1 3 2 3 City Staff Preference 1 3 1 2 Sustainability 1 3 1 2 Noise or Odor Potential 1 2 2 2 Total 13 19 13 18 5.8 Secondary Treatment (SCT) Alternatives The existing Secondary Treatment system has a capacity of 5.4 MGD average flow but future regulations will be below the effluent design conditions from 2009, of total nitrogen (TN) = 10 mg/L and total phosphorous (TP) = 1.0 mg/L. The target nutrient limits used for the alternatives evaluation in this section are the anticipated next level in nutrient limits under the MDEQ Circular 12A variance, TN = 6.0 mg/L and TP = 0.30 mg/L. The facility is already achieving an average TP effluent concentration of 0.13 mg/L, so focus will be given to TN in this section. Given the current regulatory environment, however, even lower nutrient limits are likely to occur during the planning period. The following pathways for meeting more stringent limits are also presented: • Perform a site specific study of the receiving water to determine if further reduction in nutrients, either nitrogen or phosphorous, would have an impact on the stream. The City has plans to conduct site specific sampling in Ashley Creek. See Chapter 2 for additional discussion. • Tertiary treatment or effluent management, see Section 5.10. • Sidestream treatment, see Section 5.15.2. Alternatives considered for the Secondary Treatment system are as follows: Alternative SCT 1: No Action Alternative SCT 2: Conversion to a 5-stage process Alternative SCT 3: Integrated Fixed-Film Activated Sludge (IFAS) Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-17 Alternative SCT 4: Membrane Bioreactor (MBR) Alternative SCT 5: Granular Activated Sludge (GrAS) 5.8.1 Alternative SCT 1: No Action Given the current nutrient removal performance of the facility and probable future nutrient limits, not making any modifications to the Secondary Treatment system would contain certain risks, including possible discharge permit violations. Even if the future regulatory environment were to be less stringent than currently thought, the mass loading (lb/d of nutrients introduced to Ashley Creek) for nitrogen and phosphorus currently allowed by permit is unlikely to ever be increased. As flows increase, the concentration of nitrogen and phosphorus will have to decrease to meet the same mass in the effluent. Therefore, the facility will continuously have to treat nitrogen and phosphorus to lower and more stringent levels. Table 5-10 provides a summary of the nitrogen and phosphorus concentrations that would need to be achieved in the facility effluent using the current MPDES discharge permit mass (lb/day) limits and projected maximum month flows for the planning period. Effluent total nitrogen concentrations currently average 7.8 mg/L, so TN limits will be difficult to achieve just beyond the planning horizon. Table 5-10. Future Equivalent Nutrient Concentrations Equivalent Concentration Limit (mg/L) at: 2018 2023 2028 2033 2038 Mass Limit (lb/day) 4.06 MGD 4.49 MGD 4.95 MGD 5.47 MGD 5.96 MGD Total Nitrogen 397 11.72 10.60 9.62 8.70 7.99 Total Phosphorus1 9.9 0.29 0.26 0.24 0.22 0.20 Total Phosphorus2 25.8 0.76 0.69 0.62 0.57 0.52 1. This limit applies during the period July 1st through September 30th, annually. 2. This limit applies during the period October 1st through June 30th annually. 5.8.2 Alternative SCT 2: Conversion to a 5-stage process An evaluation of the biological treatment system was conducted as part of the 2017 Facility Optimization Study. The addition of a post-anoxic and a post-aerobic zone to the bioreactor was evaluated as part of the study. A preliminary model was developed using the process modeling software BioWin version 5.1. The addition of two new zones would create a 5-stage treatment system referred to as the Bardenpho process. The post-anoxic zone would create an environment for denitrification to occur, reducing nitrate (and total nitrogen) concentrations. The post- aerobic zone would strip residual nitrogen gas from solution and would mitigate the release of phosphorous in the secondary clarifiers. Figure 5-4 presents a schematic of a typical 5-stage Bardenpho system. Preliminary analysis indicates the process will be carbon limited. Primary effluent is a potential source of carbon and can be conveyed to the post-anoxic zone through step feed operation. Methanol is an optional source of Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-18 supplemental carbon that may be utilized for dosing into the post-anoxic zone as illustrated in Figure 5-4. City staff have conducted experiments with operating a post-anoxic zone utilizing step feed of primary effluent with promising results. This alternative consists of permanent infrastructure modifications to the bioreactor in order to operate with a post-anoxic and post-aerobic zone. Modifications include construction of interior concrete walls in Cell 14 and Cell 15 to create the post-anoxic and post-aerobic zones and installation of additional submersible mixers. Methanol addition is not included in this alternative given the recent empirical results obtained by the City, but components for controlled step feed operation, i.e., pump, flow meter, piping, etc., are included. This alternative would allow for compliance with anticipated lower total nitrogen requirements in the short-term. The preliminary model was run under steady state conditions using a temperature of 14.0 °C. Actual treatment performance will vary depending on fluctuations in ambient conditions and final design should include detailed modeling. Figure 5-4. 5-stage Bardenpho Process Schematic 5.8.3 Alternative SCT 3: Integrated Fixed-Film Activated Sludge (IFAS) The IFAS process incorporates a fixed-film media in activated sludge biological basins to increase the amount of biomass in the reactor. The type of media used includes rope, sponge, plastic carrier, trickling filter media, and flat sheets. A media retention screen is used to keep media within the target basin (Figure 5-5). The attached biomass (i.e., biofilm) is not transferred out of the bioreactor leading to a reduction in solids loading to the secondary clarifiers. The configuration provides additional biomass as a result of a longer solids retention time associated with the attached biomass/biofilm. The IFAS process could be implemented in the anoxic zones (Cell 6 and Cell 7) of the bioreactor to enhance denitrification, further reducing effluent nitrate concentrations. Some of the requirements for IFAS include: • Robust primary treatment to remove large particulate matter that tends to clog media and the media retention screen Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-19 • A system to relocate media for maintenance • Media recycle pumps depending on the type of media used The existing preliminary treatment systems (i.e., influent screening and grit removal) and primary treatment systems (i.e., primary clarification) are considered sufficient for this evaluation and no modifications to those systems are included. Replacement of the existing top entry mixers in Cell 6 and Cell 7 with submersible mixers would be required. Figure 5-5. IFAS Media Depiction 5.8.4 Alternative SCT 4: Membrane Bioreactor (MBR) A membrane bioreactor (MBR) is a variation of the classic activated sludge process but relies on membrane separation of solids instead of using a secondary clarifier to capture and return biomass to the activated sludge process. The process uses microfiltration or ultrafiltration membranes to separate the biomass from the treated liquid and produce a low turbidity, filtered effluent. This process has the ability to sustain very high biomass concentrations. There are two common configurations under which membranes can be operated: • Under pressure o Membranes are in pressure vessels located outside the basin o Wastewater is pumped through membranes o Commonly referred to as an external membrane reactor • Under vacuum o Membranes are immersed in the basin o Wastewater is on the outside of the fiber or sheet and is pulled through the membrane fiber while keeping solids outside o Commonly referred to as an immersed membrane bioreactor. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-20 Some early immersed/submerged membrane designs attempted to place membranes in the aeration basin. However, more contemporary designs call for the installation of the submerged membranes in a dedicated “membrane tank” to facilitate cleaning. A separate and dedicated membrane tank is also the favorable approach for hydraulic and uniform membrane performance. For the purposes of this evaluation, the MBR alternative consists of the immersed membrane bioreactor option with dedicated membrane tanks. Conversion of existing aeration basin tankage to membrane tanks is assumed as some aeration zones are currently offline and aeration basin capacity is abundant. Alternatively, since the MBR process removes the need for secondary clarification, the clarifier structures could be used as membrane tanks. This design feature should be further evaluated during detailed engineering. The two main types of submersed polymeric membranes utilized in wastewater treatment are flat plate or hollow fiber. These two types range from microfiltration (pore sizes 2.0 to 0.08 micrometers) to ultrafiltration (pore sizes 0.2 to 0.005 micrometer). The common microfiltration pore size is 0.4 micrometers and common ultrafiltration pore size is 0.04 micrometer. As mentioned previously, immersed membrane bioreactors are typically an "outside in" style, i.e. flow is from the outside to the inside of the membrane. Permeate pumps serve to “pull” the wastewater through the membrane producing filtered water called permeate. Backpulse pumps are used to temporarily reverse flow direction to remove debris from the outside membrane surface. All flow must go through the membranes for treatment, so it is not uncommon to construct multiple membrane tanks with each tank typically having multiple membrane modules. This redundancy also allows a tank to be taken offline for maintenance and membrane chemical cleaning. Regular cleaning of the membrane surface while in service/production is typically provided by scour air from blowers. Figure 5-6 presents a possible flow scenario for MBR implementation at the Kalispell AWWTP. The flow alignments focus on nitrogen and phosphorous removal. The recycle from the membrane compartment, i.e., RAS flow, is returned to the aerobic or anoxic zone. The reason for returning the membrane recycle flow to the aeration basin instead of the anoxic zone is that the RAS flow rate is very high (multiple times the influent flow) to avoid concentration of solids around the membranes, and is saturated with oxygen. Other configurations can return the RAS to a deoxygenation zone. The existing pre- anoxic zone at the Kalispell AWWTP could potentially serve this function but detailed hydraulic calculations would need to be completed. The high MLSS concentration in the RAS exerts a significant endogenous oxygen demand that can be used to reduce the dissolved oxygen to very low values in about 15-30 minutes. When the DO is depleted, the flow can be returned to the anoxic or anaerobic zones for denitrification or phosphorus removal. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-21 Figure 5-6. MBR Flow Schematic for Nitrogen and Phosphorous Removal MLSS and Alkalinity A much higher MLSS concentration is possible with a MBR compared to a typical activated sludge process. A design MLSS range of 8,000 to 10,000 mg/L in the aeration basin is typical but will depend on oxygen transfer in the basin. Adequate alkalinity is also necessary to maintain neutral pH. A residual alkalinity greater than 50 mg/L after nitrification is recommended. Influent Screening and Grit Removal MBR processes require better wastewater pretreatment than conventional systems. Poor screening has proven to be a problem with membrane systems. Some early MBR plants used 6 mm screens and suffered from sewage debris and hair collecting and compacting on the membranes. Membrane manufacturers usually recommend using 2-3 mm screens, perforated or mesh. There should be no opportunity to bypass or overflow the screens to the MBR. Consequently, redundancy, robustness, cleaning procedures, and effectiveness of the screens should be major factors in the design. Since influent screening is much finer than for conventional plants, it is not unusual for the plant to have two-stage screening, e.g., 6-mm screen followed by 2-mm screen. Some plants provide a second fine screening on a portion of the recycle stream from the membrane tanks. When located on the recycle stream, the screen capacity may need to be greater than if located on the influent stream. The advantage of screening the membrane recycle sludge is to remove the coalesced debris and solids that agglomerate in the aeration basins. If the biological basins and membrane tanks are not covered and ambient debris is likely (leaves, pine needles, etc.), then RAS screening is recommended. For the purposes of this alternative, two-stage screening and RAS screening is assumed. Effective grit removal is also important to MBR performance. Grit abrades to the membrane and reduces its effective life. The existing vortex grit removal is assumed to be adequate for pretreatment in a MBR process. Grit abrades the membrane and reduces its effective life. The existing vortex grit removal is assumed to be adequate for pretreatment in a MBR process. However, given the importance of grit removal to AER MT RAS ANXANR DeOx Influent Effluent WAS EBPR and NDN with DeOx Zone Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-22 membrane performance, a redundant grit removal system should be considered in the future if this alternative is selected. Sludge Settleability and Thickening An advantage of MBR systems is the sludge settleability is not as critical as in a conventional activated sludge plant. Retention of more fine and colloidal materials in the membrane process added to the smaller floc size can induce poorer mixed liquor settling than conventional systems. Many owners of MBR processes state that the critical focus on maintaining suitable process biology in a conventional plant has been replaced by focusing on reliable and accurate electronic control of the system. Nevertheless, the sludge characteristics affect the fouling rate of the membranes. The thickening characteristics of the waste activated sludge from MBR systems was evaluated by the Water Environment Research Federation (WERF) in their study of the MBR Website Strategic Research project. That evaluation concluded that solids from MBRs showed no impaired thickening or dewatering characteristics compared to conventional activated sludge. Though there are contradictory evidence in the literature on the relative dewaterability of WAS from an MBR compared to a conventional system. A characteristic of longer solids retention times (SRTs) is reduced amounts of biological polymers and more dispersed and smaller flocs. While this may impair capture of solids in a thickening or dewatering operation, less biological polymer leads to less retention of water, which leads to denser sludge or drier cake. Polymers may be artificially added to increase solids capture, but polymers will not improve the thickness of the sludge or dewatered cake. No improvements to sludge thickening or dewatering are included in this alternative. Permeate Disinfection Membranes are effective barriers to bacteria and thus might be thought of as an alternative to disinfection. Additionally, although many viruses are smaller than the pore sizes used for MBR membranes, permit limits for viruses are uncommon. Even though MBR membrane pore sizes are small enough to exclude coliform bacteria, experience with MBR has shown that coliforms are still detectable in MBR effluent samples. The MBR process will meet typical permit limitations for numbers of coliform bacteria – unless there is a defect in a membrane. Because coliforms are routinely measured in MBR effluent, regulatory agencies continue to require separate disinfection in addition to the membrane barrier. Coliform bacteria have long been used as a surrogate for pathogens with the thinking that chemical disinfectants (or UV) will destroy, or deactivate, pathogens. There continues to be the need to provide separate disinfection in addition to the membranes in MBR systems. Many MBR plants use UV as a disinfection process, some running the system at low intensity to meet discharge permit limitations. No improvements or modifications to disinfection are included for this alternative. 5.8.5 Alternative SCT 5: Granular Activated Sludge (GrAS) Granular activated sludge (GrAS) is a newer technology that employs the granulation concept documented in anaerobic treatment. An environment in the secondary treatment Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-23 system is created where granular sludge is the dominant form of bacteria. A feast/famine environment is created to select for bacteria that can store substrate. The spherical shaped bacteria take approximately 40 days to form but settle fast and have a high mass transfer area. Nitrifying microorganisms form on the outside of granules and dentrifiers on the inside. With other technologies heterotrophs form on the outside and remove carbon before it can get to denitrifiers for use. The granules are not like flocs where the microbial community is mixed and continually changing spatially. Granules do not coagulate or flocculate. There are no specific granular microorganisms, all microorganisms can be grown this way. Similar to the IFAS process, the GrAS process can add capacity to an existing system due to the small footprint required. However, as mentioned previously the Secondary Treatment system has capacity for the planning period. Additionally, the granules are dominant in plug-flow situations, e.g., sequencing batch reactors. Figure 5-7 presents a process flow schematic of a commercially available GrAS product. Research is still ongoing for continuous flow applications. There are full scale GrAS installations globally but most research has been lab scale experiments. Limited research has been conducted on low nutrient levels considered in this facility plan. Sludge testing for granulation and process piloting would be recommended prior to further consideration. Therefore, additional evaluation of this alternative is not conducted at this time. Figure 5-7. Commercial GrAS Product Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-24 5.8.6 Alternative Costs Table 5-11 presents costs for Secondary Treatment Alternatives SCT 2, SCT 3, and SCT 4. Cost for each alternative is discussed in the following section. Table 5-11. Secondary Treatment Alternative Costs Alternative Construction Cost Estimate 1,2 SCT 2: Conversion to 5-stage process $ 986,000 SCT 3: IFAS $ 895,000 SCT 4: MBR $ 16,189,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.8.7 Recommended Alternative Table 5-12 presents scoring for the Secondary Treatment alternatives. Table 5-12. Secondary Treatment Alternatives Scoring Evaluation Criteria SCT 2 SCT 3 SCT 4 Construction Cost 2 3 1 Future Flexibility 3 3 1 O&M Requirements 3 1 1 Implementation 3 2 1 Operational History 2 2 2 City Staff Preference 3 2 2 Sustainability 3 2 2 Noise or Odor Potential 2 2 2 Total 21 17 12 Alternative SCT 2 - Conversion to a 5-stage process, scored the highest in this evaluation. The relative low cost, ease of implementation, and future flexibility are strong Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-25 reasons for the score. This alternative has the second highest cost but consists of less complex O&M requirements compared to the other two alternatives. Interior concrete walls in the bioreactor were assumed for implementation of this alternative but curtain baffles could be installed to reduce costs. Alternative SCT 3 – IFAS had the second highest score overall and lowest construction cost estimate. Although initial capital costs are low for this alternative there are several additional items to consider: • Media Clogging o Biofilm thickness is affected by mixing pattern and BOD loads. To mitigate this problem media of different pore size can be placed in different zones. • Screen Plugging o Starvation of organics may lead to ciliates buildup. Plug flow configuration leads to media migration towards screens. • Maintenance of aeration system o Carrier media must be removed from system and displaced during maintenance, space and potentially labor intensive. • Predators o Pore size and organic loads fluctuation impact predator growth, e.g., worms • Plant hydraulics o Media and media retention screen can inhibit hydraulics • Media life expectancy o Typical life expectancy is 10 - 30 years Alternative SCT 4 – MBR has a high construction cost estimate and low evaluation score. A new equipment building to house blowers, pumps, etc. was assumed but if the secondary clarifiers are used as membrane tanks then the existing RAS Building could be used to house new equipment. Although that option would reduce costs for implementing a MBR, the comparative cost to Alternatives SCT 2 and SCT 3 would still be substantially higher. The recommended alternative is Alternative SCT 2 – Conversion to a 5-stage process. 5.9 Secondary Clarification (SCL) Alternatives The secondary clarifiers have experienced nuisance algae growth and water fowl activity. Alternatives considered for Secondary Clarification are as follows: Alternative SCL 1: No Action Alternative SCL 2: Install Launder Covers Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-26 Alternative SCL 3: Install Flat Clarifier Covers Alternative SCL 4: Install Dome Clarifier Covers 5.9.1 Alternative SCL 1: No Action Alternative SCL 1 makes no changes to current operating or cleaning conditions. The secondary clarifiers will continue to have issues with algae growth and sloughing, reducing effluent filter tank volume and negatively impacting filter performance. The secondary clarifiers would also continue to be exposed to ducks and geese. This alternative requires no immediate capital cost, but reduces plant effluent quality and results in continued operational problems. 5.9.2 Alternative SCL 2: Install Launder Covers Alternative SCL 2 would cover the effluent launder of all three secondary clarifiers. The launder covers can be metal or fiberglass reinforced plastic (FRP) and have access hatches for inspection of the weir. See Figure 5-8 for an example launder cover. The covers would greatly reduce the algae growth on the weir, also reducing the potential for odors, but still leaves the center portion of the clarifier exposed to ducks and geese. Figure 5-8. Example Launder Cover 5.9.3 Alternative SCL 3: Install Flat Clarifier Covers Alternative SCL 3 would completely cover the secondary clarifiers with flat covers (Figure 5-9). Covers are commonly made of rigid aluminum or FRP, with access hatches to the surface of the tank allowing for limited inspection. This type of cover does not require, but allows for, the installation of a HVAC/odor control system, reduces algae growth by blocking UV light, and prevents waterfowl from accessing the clarifier water surface. A flat cover is similar to the existing cover on the fermenter. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-27 Figure 5-9. Example Flat Clarifier Cover 5.9.4 Alternative SCL 4: Install Dome Clarifier Covers Alternative SCL 4 would completely cover the secondary clarifiers with aluminum, dome covers (Figure 5-10). A dome cover allows for full access to the clarifier for inspection and maintenance. Ventilation of the space, 12 air changes per hour, would be required to provide a safe working environment. Similar to Alternative SCL 3, algae growth and odor production will be reduced, and waterfowl will be kept out of the clarifiers. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-28 Figure 5-10. Example Dome Clarifier Cover 5.9.5 Alternative Costs Table 5-13 presents costs for Secondary Clarification Alternatives SCL 2, SCL 3, and SCL 4. The cost for Alternative SCL 2 is to cover the launder of all three secondary clarifiers. The costs for Alternative SLC 3 and SLC 4 are for covering the North and South Secondary Clarifiers (Secondary Clarifiers 1 and 2). Secondary Clarifiers 1 and 2 could be covered first and the East Secondary Clarifier (Secondary Clarifier 3) covered a year or two later. Secondary Clarifier 3 has weir brushes which helps mitigate the algae growth issue but not address the waterfowl nuisance. However, prioritizing Secondary Clarifiers 1 and 2 first will have a greater impact on plant operations and phases the cost of covering the secondary clarifiers. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-29 Table 5-13. Secondary Clarification Alternative Costs Alternative Construction Cost Estimate 1,2 SCL 2: Install Launder Covers $ 433,000 SCL 3: Install Flat Clarifier Covers $ 2,070,0003 SCL 4: Install Dome Clarifier Covers $ 2,439,0003 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 3. Cost of covering the North and South secondary clarifiers (Secondary Clarifiers 1 and 2) only. 5.9.6 Recommended Alternative Table 5-14 presents scoring for the Secondary Clarification alternatives. The no action alternative scored the lowest as it does not address the algae growth and water fowl issues. The launder cover alternative has the lowest cost and scored well but does not address the water fowl issue. Additionally, during winter months foam on the clarifiers freezes. Installation of launder covers would make removal of the frozen foam difficult or impossible. Alternative SCL 4 – Install Dome Clarifier Covers is the most expensive alternative proposed for covering the secondary clarifiers. This added expense is not necessary to address the issues City staff have experienced. Alternative SCL 3 – Install Flat Clarifier Covers scored the highest in the evaluation and is second least expensive option. The recommended alternative is Alternative SCL 3. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-30 Table 5-14. Secondary Clarification Alternatives Scoring Evaluation Criteria SCL 1 SCL 2 SCL 3 SCL 4 Construction Cost 3 2 1 1 Future Flexibility 3 3 1 1 O&M Requirements 1 2 3 2 Implementation 3 2 1 1 Operational History 1 2 3 3 City Staff Preference 1 2 3 3 Sustainability 1 2 3 3 Noise or Odor Potential 1 1 3 3 Total 14 16 18 17 5.10 Effluent Filtration (EFF) Alternatives The effluent sand filters are a hydraulic restriction during peak flows and are in poor condition. Additionally, as discussed in Section 5.8, future nutrient limits are likely to exceeded the nutrient removal capacity of existing treatment processes, so additional treatment or other measures will be required. The target nutrient limits used for the alternatives evaluation in this section are TN = 3.0 mg/L and TP = 0.05 mg/L, which are the limits of technology and the anticipated nutrient levels just prior to reaching variance limits. Alternatives considered for Effluent Filtration are as follows: Alternative EFF 1: No Action Alternative EFF 2: Tertiary Membrane Filtration Alternative EFF 3: Effluent Management 5.10.1 Alternative EFF 1: No Action Alternative EFF 1 consists of maintaining current operation of the effluent sand filters. Excessive headloss through the effluent filters results in flow of unfiltered water directly to the downstream UV disinfection system. The excess flow is higher in total suspended solids which decreases UV system performance. The City is currently meeting discharge permit limits with the filters but did receive a quote from the filter manufacturer to replace the sand in all modules. The cost was approximately $200,000. The City does not consider replacement of the sand in the existing filters necessary at this time and thinks the funds could be used for improvements leading to better effluent treatment and water quality. The No Action alternative will not be examined further. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-31 5.10.2 Alternative EFF 2: Tertiary Membrane Filtration (TMF) Tertiary membrane filtration (TMF) is the most common treatment process available to meet the anticipated nutrient limits within the planning horizon. TMF is similar to the MBR process described in Section 5.8.4. The primary difference between TMF and MBR is that the secondary clarifiers remain online for the TMF process and the membranes are located downstream of the secondary clarifiers (Figure 5-11). In other words, secondary effluent is filtered with membranes for an additional level of treatment. A preliminary assessment indicates a pumping station may be required to pump secondary effluent to the TMF process. The existing sand filter tanks would be proposed for use as membrane tanks, but due to the process redundancy recommended for membranes, additional tankage would likely be required. Also, similar to the MBR process alternative, an equipment building would be required to house blowers, pumps, chemical cleaning equipment, electrical equipment, etc. A potential location for the TMF facility would be just north of the existing effluent filter area. The existing building, including the nearby chemical room, could be modified for implementation of the TMF process. Detailed design and hydraulic calculations would be required to determine the extent of the usefulness of the existing effluent filter area and decide the final location of a TMF facility. New membrane technologies are continually emerging. One such technology is manufactured by Fibracast. The Fibracast FibrePlate filtration membranes are described as hybrid-membranes, combining the features of hollow-fiber and flat-plate membrane technologies. Fibracast claims improved filtration performance, greater strength, extended sustainable flux rate, space efficiency, optimized cleaning, and lower overall capital and operational costs. The most significant benefits claimed by the manufacturer are a smaller overall footprint (approximately 50% less space required compared to competing membrane technologies), 40% less air scour energy, 30% higher flux rates, and in-situ membrane recovery to prevent plant upsets. Additional time is needed with full-scale operation and site-specific criteria would be evaluated prior to implementation of any new technology, but such a reduction in footprint could have a positive impact on costs and provide more opportunity to use existing infrastructure. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-32 Figure 5-11. TMF Flow Schematic 5.10.3 Alternative EFF 3: Effluent Management Another approach to the pending stringent nutrient limits would be to manage effluent from the facility differently. Two alternative methods of effluent management are water reuse and groundwater recharge. Both methods consist of limiting or eliminating effluent discharge to Ashley Creek. Water Reuse Treated wastewater is already beneficially reused in many ways throughout the United States. The public often perceives direct reuse, such as agricultural and landscape irrigation, cooling water, environmental enhancement, or potable (drinking) water, as the only means treated wastewater is reused. However, most reuse is through indirect means, such as river discharge upstream of a water intake or diversion, discharge to a lake or reservoir that is source water for another use, or recharge to an aquifer with other uses such as water supply. Indirect reuse is not often discussed beyond wastewater treatment plant discharges or mixing zones, whereas, direct reuse is a provocative topic of discussion for water resources managers. Water reuse in Montana is regulated by the MDEQ. Standards for irrigation and rapid infiltration systems are included in MDEQ Circular DEQ-2 Chapter 120. Appendix B of Circular DEQ-2 lists reclaimed wastewater classifications and uses. Implementation of a water reuse program involves multiple steps. These steps involve public awareness, permitting, demonstration, phased construction, operations, maintenance, and management. Public acceptance, or disapproval, has become a major issue in many communities choosing to develop a reuse program. A public awareness program is important throughout all stages of developing a reuse program, from planning through operation, in order to engage the community and emphasize the value of wastewater reclamation. Several reclamation projects have not progressed beyond the planning stages due to public objection. The failure to engage the public and to keep them engaged is a major contributing factor to the public disapproval of planned reuse programs. A demonstration project that is modest in size and cost could be an element of Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-33 a successful public awareness project to support development of a reuse program. If the City were able to show actual reclaimed water being used on a small demonstration scale, the public may become more familiar with its application, safety, and benefits. Groundwater Recharge Another alternative method to effluent management is groundwater recharge. Infiltration/percolation (I/P) basins are filled with facility effluent and pass through to groundwater. Infiltration of treated facility effluent into the groundwater can help reduce or stop the decline in groundwater levels during the summer, provide for storage of surface water for later use, and provide increased flows to surrounding streams during dry periods which protects stream habitat. Being a natural system, recharge basins also provide for a finishing treatment mechanism of the highly treated water as it passes through the soil strata into the groundwater aquifer. The soils filter and condition the water as it moves down through the soil layers and underlying geologic structures into the aquifer. The I/P basins provide a path for the reclaimed water to reach the shallow aquifer in a managed and efficient manner. By infiltrating the reclaimed water into the shallow aquifer, the water becomes a renewable resource available to the entire community and decreases dependence on discharge to Ashley Creek. Another potential benefit to groundwater recharge would be cooling of effluent which could mitigate temperature impacts on Ashley Creek. In order to determine the feasibility of discharging the highly treated effluent to the subsurface, a Recharge Feasibility Investigation must be conducted. At a minimum, the Feasibility Investigation must determine: • Depth to groundwater; • Horizontal and vertical hydraulic conductivity; • Soil classification; • Travel time to the nearest surface water; • Required recharge basin size; and • Impacts of recharge on groundwater elevation. Should the feasibility prove positive, the City could then proceed with the necessary modeling, design, reporting necessary for acquisition of a State groundwater discharge permit. The potential use of groundwater would enable the City to fully recycle reclaimed water generated at the AWWTP throughout the entire calendar year and allow a portion of the effluent to be directed away from the existing surface water discharge. The City would maintain their surface water discharge to maintain the long-term viability of the utility in its current location. The use of the groundwater discharge should be considered an additional option for ensuring an economical way to meet receiving water requirements and managing the total volume of the effluent. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-34 Summary The combination of water reuse and groundwater recharge can greatly reduce the amount of treated effluent discharged to Ashley Creek and thereby reduce the total nutrient load discharged to the receiving water. Combining and implementing the groundwater recharge and water reuse recommendations described above could allow zero discharge to Ashley Creek during the summer, for all or part of the planning period. However, the exact nature of water discharged by municipalities in Montana is vague. Water rights are an important component when considering alternative methods of effluent management. An in-depth review of Montana legislation is necessary to understand the issues surrounding water use and reuse, water source definitions, and water appropriators. Additionally, discussions with City staff indicate available land in the vicinity of the AWWTP is limited and growth around the facility is increasing, lessening the feasibility of alternative effluent management methods and potentially making them cost prohibitive. The effluent management alternative is not given further consideration here. However, a recommendation to conduct a comprehensive effluent management plan is included under miscellaneous improvements in Section 5.15 if the City chooses to pursue this option. Given the intricate public/private interface with effluent management and the complex regulations and legal issues surrounding water quality and water rights, a thorough plan should be conducted prior to implementing alternative effluent management strategies. 5.10.4 Alternative Costs Table 5-15 presents a construction cost estimate for Effluent Filtration Alternative EFF 2. Table 5-15. Effluent Filtration Alternative Costs Alternative Construction Cost Estimate 1,2 EFF 2: Tertiary Membrane Filtration $ 18,000,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.10.5 Recommended Alternative Table 5-16 presents scoring for the Effluent Filtration alternatives. Alternative EFF 1: No Action scores high for cost and implementation, but does not address the future effluent limits anticipated by the City. Alternative EFF 2: TMF provides an option for the high level of treatment required. The TMF process has been implemented at other regional wastewater treatment facilities with a successful performance history. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-35 The recommended alternative for Effluent Filtration is Alternative EFF 2. Table 5-16. Effluent Filtration Alternatives Scoring Evaluation Criteria EFF 1 EFF 2 Construction Cost 3 1 Future Flexibility 2 1 O&M Requirements 1 2 Implementation 3 2 Operational History 1 2 City Staff Preference 1 2 Sustainability 1 2 Noise or Odor Potential 1 2 Total 13 14 5.11 Reaeration Basin (RAB) Alternatives The reaeration basin is within the 100-year floodplain and flood protection of the structure is recommended. Alternatives considered for the Reaeration Basin are as follows: Alternative RAB 1: No Action Alternative RAB 2: Reaeration Basin Modifications Alternative RAB 3: Relocation of Reaeration Basin 5.11.1 RAB 1: No Action The reaeration basin does not require any modifications for performance reasons, but does reside within the 100-year flood plain. No modifications to the structure does not mitigate the risk of future flooding of the reaeration basin. 5.11.2 RAB 2: Reaeration Basin Modifications Raising the walls and adding a cover to the reaeration basin would mitigate flooding events and reduce effluent temperatures. The existing basin has a top of concrete wall elevation of 2922.0 FT while base flood elevation is 2928.5 FT. Similar to Alternative INP 3, construction would take place in a Special Flood Hazard Area and will require a Letter of Map Revision be submitted to FEMA. Hydraulic analysis will need to be performed before commencing work and the flood plain map potentially revised. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-36 5.11.3 RAB 3: Relocation of Reaeration Basin Alternative RAB 3 consists of demolition of the existing reaeration basin and construction of a new reaeration basin outside of the 100-year flood plain. The new basin would be to the east of its current location, near the fermenter. This alternative would require new piping, concrete work, and relocation of the effluent monitoring structure. Alternative RAB 3 would also cover the new basin to attenuate effluent temperature fluctuations. 5.11.4 Alternative Costs Table 5-17 presents costs for Reaeration Basin Alternatives RAB 2 and RAB 3. Table 5-17. Reaeration Basin Alternative Costs Alternative Construction Cost Estimate 1,2 RAB 2: Reaeration Basin Modifications $ 260,000 RAB 3: Relocation of Reaeration Basin $ 1,195,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.11.5 Recommended Alternative Table 5-18 presents scoring for the Reaeration Basin alternatives. Alternative RAB 3 scored the lowest and has the highest cost. The no action alternative, RAB 1, scored the second highest but would not address the City’s preferences to protect the structure and reduce effluent temperature. The recommended alternative, Alternative RAB 2, scored the highest of the alternatives evaluated and has the lowest cost of the alternatives including action. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-37 Table 5-18. Effluent Filtration Alternatives Scoring Evaluation Criteria RAB 1 RAB 2 RAB 3 Construction Cost 3 3 1 Future Flexibility 2 2 1 O&M Requirements 2 2 1 Implementation 3 3 1 Operational History 1 2 1 City Staff Preference 1 3 1 Sustainability 1 2 2 Noise or Odor Potential 1 2 2 Total 14 19 10 5.12 Anaerobic Digestion (AND) Alternatives The anaerobic digestion system consists of, in part, a single primary digester, single heat exchanger, and aging digester recirculation pumps. Primary digester redundancy is addressed under one alternative and the heat exchanger and pumps under a separate alternative. Alternatives considered for Anaerobic Digestion are as follows: Alternative AND 1: No Action Alternative AND 2: Second Heat Exchanger and New Recirculation Pumps Alternative AND 3: Second Primary Digester 5.12.1 Alternative AND 1: No Action The no action alternative consists of a continuation of existing equipment operation and maintenance. This alternative has the potential to leave operations staff without necessary treatment processes or operational flexibility during equipment failure or maintenance. 5.12.2 Alternative AND 2: Second Heat Exchanger and New Recirculation Pumps This alternative consists of replacing the existing recirculation pumps and installing a second heat exchanger. Replacement of the pumps will be required, as the existing pumps are already nearing the end of their useful life. The installation of a second heat exchanger will provide redundancy to the primary digester and reduce equipment downtime. Replacement of the existing heat exchanger is also included in this Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-38 alternative as the existing heat exchanger is near the end of its useful life and newer heat exchangers have smaller footprints. Space is limited in the Boiler Room where the heat exchanger is currently installed so smaller equipment will likely be required to install two units. 5.12.3 Alternative AND 3: Second Primary Digester Alternative AND 3 involves adding a second 50-FT diameter primary digester with appurtenances. A preliminary location for the second primary digester is northwest of the existing primary digester. Constructing a second primary digester will provide operational flexibility, process stability, and an approximate 33% increase in total anaerobic digestion volume. 5.12.4 Alternative Costs Table 5-19 presents costs for Anaerobic Digestion Alternatives AND 2 and AND 3. Table 5-19. Anaerobic Digestion Alternative Costs Alternative Construction Cost Estimate 1,2 AND 2: Second Heat Exchanger and New Recirculation Pumps $ 828,000 AND 3: Second Primary Digester $ 3,994,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.12.5 Recommended Alternative Table 5-20 and Table 5-21 presents scoring for the Anaerobic Digestion alternatives. When Alternatives AND 2 and AND 3 are each compared to a no action alternative and both score high. Because of the lack of digestion tank redundancy and the lack of ability to easily remove an existing digester for cleaning, construction of the new primary digester and its associated support facilities (Alternative AND 3) is recommended. Alternative AND 2 is also recommended for implementation to provide equipment redundancy and reliability. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-39 Table 5-20. Anaerobic Digestion Equipment Alternatives Scoring Evaluation Criteria AND 1 AND 2 Construction Cost 3 2 Future Flexibility 3 2 O&M Requirements 1 2 Implementation 3 2 Operational History 1 2 City Staff Preference 1 3 Sustainability 1 2 Noise or Odor Potential 2 2 Total 15 17 Table 5-21. Anaerobic Digestion Primary Digester Alternatives Scoring Evaluation Criteria AND 1 AND 3 Construction Cost 3 1 Future Flexibility 1 3 O&M Requirements 1 2 Implementation 3 1 Operational History 1 3 City Staff Preference 1 3 Sustainability 1 2 Noise or Odor Potential 2 2 Total 13 17 5.13 Sludge Thickening (STK) Alternatives Existing waste activated sludge (WAS) thickening equipment is near the end of its useful life and in need of replacement. Alternatives considered for Sludge Thickening are as follows: Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-40 Alternative STK 1: No Action Alternative STK 2: New DAFT System Alternative STK 3: Gravity Belt Thickener (GBT) Alternative STK 4: Disc Thickener Alternative STK 5: Rotary Drum Thickener (RDT) Alternative STK 6: Screw Press Alternative STK 7: Volute Thickener Alternative STK 8: Centrifuge 5.13.1 Alternative STK 1: No Action The current DAFT system is over 20 years old, with both DAFT currently unusable due to tank corrosion. Making no modifications to the existing equipment hinders plant performance and restricts operational capabilities. 5.13.2 Alternative STK 2: New DAFT System Full replacement of the existing DAFT system with equivalent sized units is assumed for this alternative. The existing pressurization system would be replaced with either an in- kind replacement of the existing pressurization system or an alternate technology. The current pressurization system combines DAFT effluent recycle with high pressure air, with the mixture routed to a pressurization tank. The pressurized flow from the tank is routed through a pressure relief valve prior to the DAFT tank. An alternative pressurization system is a self-aspirating pump. Two pump types, the EDUR LUB and the Cornell DAF series, consist of multistage centrifugal pump impellers to create a sub- atmospheric pressure region in the pump chamber, forming compressed micro-bubbles that are dissolved into the flow. Air to liquid ratio can be adjusted using valves on the air inlet and at the pump discharge. This pump type eliminates the need for an air supply compressor and a pressurization tank. Figure 5-12 shows a typical liquid-gas mixing multi-stage centrifugal pump. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-41 Source: EDUR LUBX series Figure 5-12. Typical Liquid – Gas Mixing Centrifugal Pump Another type of the air-aspirating system consists of a compact micro-bubble generator and associated control valves, flow, and pressure monitoring instruments. Figure 5-13 shows a typical air-aspirating micro bubble generator. The generator automatically draws air in through an injection nozzle. Air is mixed and dissolved into the recycled flow from the DAFT tank by an air liquid mixer inside the generator. The generator then pressurizes the air-entrained flow and feeds to the DAFT tank. Similar to the liquid-gas mixing pumps, this micro-bubble generator performs air feeding, dissolving, and mixed liquid pressurization in a single unit. The micro-bubble generator can replace the entire conventional pressurization system, including a centrifugal recycle pressurization pump, a pressurized air saturation tank, an air release valve, and a high pressure air compressor. Source: Pictures are from NIKUNI Technical Booklet Figure 5-13. Typical Air-aspirating Micro-Bubble Generator Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-42 Source: Pictures are from EDUR Figure 5-14. DAFT Unit with Air-aspirating Pump System Figure 5-14 shows a DAFT treatment system with an alternative air-aspirating pump system in place of the conventional pressurization system. Table 5-22 compares the characteristics of the conventional pressurization system and an alternative air-aspirating pump system. The air-aspirating pump system has several advantages compared to a conventional system, including simpler system configuration, smaller footprint, automatic air intake and dissolution, smaller bubble size, improved DAFT performance, reduced maintenance requirements, significant energy savings, and quieter operation. A disadvantage of the air-aspirating pump system is a capacity limitation of 250 gpm for the NIKUNI KTM pumps, which typically restricts use of this equipment type to small DAFT systems. However, according to the pump vendors, multiple pumps or micro- bubble generators can be operated in parallel to increase the capacity. The life of the micro-bubble generator is usually shorter than a conventional pressurization system due to wear in air and liquid mixing. However, the life cycle cost of the air-aspirating pump system may be less than the conventional system due to the lower capital and energy and maintenance costs. Due to the capacity limitations, there is limited use of self- aspirating pumps on municipal DAFTs, and the equipment is more commonly used for industrial applications. This alternative includes the use of air-aspirating pump system with new DAFT tanks. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-43 Table 5-22. Air-aspirating Pump System and Conventional Pressurization System Comparison Category Conventional Pressurization System Air-aspirating Pump System System Configuration System consists of multiple key components, including centrifugal pump, pressurized tank, and high pressure air compressor System only consists of one key unit, the micro-bubble generator. Air Dissolution Method Air introduced by a high pressure air compressor and dissolved and pressurized into liquid by using a pressure tank. Air injected automatically, then dissolved and pressurized by an air liquid mixer in the generator Air bubble size Larger bubble size (0.01 to 0.1 mm), with wider variation Smaller bubble size (~0.005 mm) with less size variation resulting in higher density and more stable bubble cloud DAFT performance Typically ninety four to ninety nine percent of suspended solids removal with a properly designed and operated DAFT system Improved DAFT performance due to small bubble size which can remain is solution longer and result in greater solids capture Footprint Large Small System Operation Flexibility More complicated to operate, but the system provides more flexibility to accommodate variable loading due to adjustment allowed on the pump and air supply More simple system to operate; provides some flexibility, but may not be as flexible as the conventional pressurization system Maintenance Required More maintenance required due to multiple equipment in the system Less maintenance required Energy Consumption Higher energy consumption Lower energy consumption Noise More noise due to the air compressor Less noise Equipment Life ~20 years 8 to 10 years System Application Can be sized to any municipal DAFT system Has a size limitation for up to 250 gpm; most commonly used in small municipal DAFT system and industrial DAFT systems Startup and Controls Challenging startup to balance air supply and pressurization pump speed Simpler startup, with fewer components to balance. 5.13.3 Alternative STK 3: Gravity Belt Thickener (GBT) Gravity belt thickeners (GBTs) have the advantage of being relatively easy to operate but can be difficult to maintain. The primary mechanism of liquids/solids separation is by gravity-induced filtration. One unit consists of a rotating belt on a steel table. Pre- conditioned sludge is distributed onto the woven nylon belt, and plows positioned just Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-44 above the belt sort through the sludge and form small channels in which free water can drain through the belt (Figure 5-15). GBTs perform best when thickening sludge that readily flocculates, such as WAS. The addition of polymer is necessary upstream of the unit to guarantee proper coagulation and solids retention on the belt. After filtration sludge is scraped from the belt and conveyed to a hopper. Free water is collected in troughs under the belt and transported to a filtrate collection system. Figure 5-15. Example Gravity Belt Thickener The filtration and capture rate depend on several factors. A larger belt width provides more surface area for filtration, so the influent hydraulic and solids loading rates are congruently increased as well. The tension of the belt must be evenly distributed to avoid pooling of sludge and prevent unfiltered sludge from reaching the hopper. Additionally, the nylon belt must undergo periodic washing by sprayers or booster pumps to prevent pore clogging and improve solids capture. The rotation speed of the belt may also affect the capture rate; in general, a slower rotation speed results in a slower filtration rate but thicker sludge. A capture rate of 98% and thickening to 4 – 13% total solids are typical for gravity belt thickeners. 5.13.4 Alternative STK 4: Disc Thickener A disc thickener consists of an inclined cylindrical tank with an internal disc filter that separates the tank into two sections: one for thickened sludge holding and one for filtrate collection (Figure 5-16). This technology is similar to gravity belt thickeners because it removes water from WAS via gravity-driven filtration, but the shape and enclosed design differences make it more suitable for applications in which a wet atmosphere is undesirable. The tank inlet collects sludge that has undergone flocculation with polymer addition onto the disc filter. This filter often contains a perforated base disc covered with a micro-filter, which rotates around the inclined vertical axis. As the sludge is distributed onto the disc, suspended and self-adjusting plows form channels on the filter, which helps free water to drain through the filter more easily. A rubber scraper that connects from the center of the Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-45 disc to the sludge outlet scrapes sludge from the filter and gathers it into the discharge system. A spray bar positioned between the sludge inlet and discharge backwashes the filter to keep pores from becoming clogged. After free water is released, it is collected into the lower portion of the tank unit, and ejected via the filter outlet. A disc thickener can achieve greater than 6% total solids thickening results and over 85% percent sludge volume reduction. This performance depends on the polymer dose, backwash cleaning frequency, and the disc rotation speed. Figure 5-16. Huber Twin Disc Thickener 5.13.5 Alternative STK 5: Rotary Drum Thickener (RDT) Rotary drum thickeners have become increasingly popular because the covered-drum design allows for better odor control compared to gravity belt thickeners. Since the two technologies operate on similar principles, rotary drum thickeners provide an alternative in situations where gravity belt thickeners are appropriate, while providing comparable performance. Although individual designs vary, the basic mechanisms of all rotary drum thickeners are the same. A typical RDT setup is illustrated in Figure 5-17. Polymer is injected into the feed sludge prior to entering the rotary drum thickener. The influent solids then enter a flocculation tank with a stainless steel wedge wire, perforated plate, or wire mesh drum. A mechanical mixer rotates the screen drum with a drum drive generally consisting of a gear-motor and synchronous drive belt. Internal and external spray bars spray through the screen to allow for suitable free water drainage, after which this water is dismissed as additional filtrate. Radial flights inside the drum transport the thickened sludge to the discharge end, while free water flows through the drum screen openings and exits via a filtrate collection system. This design accommodates a more rigorous handling of the sludge than seen in a gravity belt thickener, so filtrate collection can occur more efficiently. However, floc shear must remain low enough to prevent sludge particles from breaking and passing through the Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-46 drum screen. Operators can control the capture rate by adjusting the feed rate, polymer dose, spray water cycling, and drum rotation speed. Overall performances depend on influent sludge quality, but other facilities have seen thickening to 5-7% total solids and up to 98% capture can be reasonably expected. Figure 5-17. Parkson Rotary Drum Thickener 5.13.6 Alternative STK 6: Screw Press A screw press is a slow-moving thickening or dewatering technology that can either be horizontally fitted or inclined. Major elements of the thickening section of the design include a sludge inlet, the screw drive, a rotating screw shaft inside a cylindrical sieve, an enclosed compartment for filtrate collection, and a thickened sludge outlet pipe. Typical installation of a screw press is shown in Figure 5-18. Figure 5-18. Huber Screw Press Thickener The sludge is pre-conditioned with polymer addition before entering the main compartment, where initial filtration occurs by gravity. As the conical screw shaft transports the sludge further down the compaction chamber by slow rotation (0.2 – 1.5 Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-47 rpm), the spacing between screw flights decreases so sludge is pressed against the sieve surface and more free water passes through. The pressing force can be adjusted by varying the position of the cylindrical filter. At the end of the compaction chamber, thickened sludge is subjected to a pneumatic counter-pressure cone at the sludge discharge location. The rotating screw pushes the sludge past the cone into the discharge collection system. The filtrate is collected by the outer compartment shell and released via a filtrate outlet pipe. In some designs, steel brushes fitted to the screw edge continuously clean the filter, and periodic cleaning occurs by backwashing with high-pressure water sprayers outside the sieve. However, some screw presses require manual periodic cleaning. The capture rate of a screw press is generally upwards of 97% and the total solids output varies by rotation speed, influent sludge quality, and the position of the pressure cone. 5.13.7 Alternative STK 7: Volute Thickener A volute thickener is very similar to the existing volute press that the City currently uses for biosolids dewatering. It operates on similar principles seen in a rotary drum thickener, but differs by the materials used for solids capture. It is suitable for applications requiring complete automation and little maintenance. Additionally, volute thickeners prevent clogging by utilizing a filtration system with moving parts; as a result, there is no need for external cleaning and wash water is significantly reduced. WAS is dosed with polymer before entering a flocculation tank where solid particles agglomerate and allow for the separation of solids and free water. The sludge then overflows to a cylindrical drum with a large Archimedean screw inside. The walls of the drum are formed by fixed plastic rings separated by spacers. Moving plastic rings with a slightly narrower width and smaller inside diameter are located between each fixed ring, and the screw shifts these rings as it rotates. This configuration of rings produces small gaps which allow free water to pass through to a collection and discharge system. The thickened sludge is pushed down the length of the drum by the rotating screw and exits via a discharge outlet at the opposite end (Figure 5-19). A volute thickener is expected to produce 3-12% total solids output and approximately a 99% capture rate. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-48 Figure 5-19. PW Tech Volute Thickener 5.13.8 Alternative STK 8: Centrifuge Centrifuges are a good option when complete automation and small footprint are desirable, but they can be cost prohibitive and energy intensive. The basis of sludge thickening in this technology is an induced centripetal force that causes solids to settle faster than in a clarifier or gravity thickener. Two main components in a centrifuge include a bowl with both a cylindrical and conical portion, and an internal scroll conveyer (Figure 5-20). The bowl is fitted horizontally and spun about an axis at a high rotational speed (at least 1,500 rpm) to create a centripetal force that presses solids against the bowl wall. The scroll is spun at a speed 10 – 20 rpm faster or slower than the bowl which generates a differential speed. The solids are transferred by the scroll to the conical end of the centrifuge while water is released at the other end. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-49 Figure 5-20. Centrisys Centrifuge Thickener Factors affecting centrifuge performance include bowl dimensions, polymer dosage, differential speed between the scroll conveyer and the bowl, and the scroll configuration. The high level of process automation within the centrifuge design has required most units to be pre-equipped with variable instrumentation settings based on influent and discharge measurements. Centrifuges typically produce effluent sludge with higher total solids concentrations than obtained with other sludge thickening technologies. 5.13.9 Sludge Thickening Alternatives Comparison Energy Consumption Table 5-23 summarizes typical energy requirements (horsepower) for each sludge thickening technology based on the feed flow and production requirements. The energy requirements are based on industry experience, literature review, and vendor websites. The disc thickener, RDT, screw press, and volute thickener all have low energy requirements. The centrifuge, as previously mentioned, has a very high energy requirement. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-50 Table 5-23. Sludge Thickening Energy Consumption Comparison Technology hp GBT 8 Disc Thickener 2.25 RDT 3 Screw Press 1.5 Volute Thickener 4 Centrifuge 150 Polymer Consumption Table 5-24 summarizes typical polymer consumption ranges (lb active/dry ton of solids or lb/dt) for each sludge thickening technology. These values are based on industry experience, literature review, and vendor websites. However, since polymer use can be heavily dependent on sludge characteristics, the actual amount of polymer use for each technology is best determined by polymer tests with sludge samples from the plant. Most thickening technologies are comparable for polymer consumption with GBTs and disc thickeners potentially requiring more polymer. Table 5-24. Sludge Thickening Polymer Consumption Comparison Technology lb/dt GBT 13 Disc Thickener 11 – 13 RDT 7 - 8 Screw Press 6 – 10 Volute Thickener 8 – 15 Centrifuge 2 - 3 Water Consumption Water consumption of each technology varies by their respective clogging potential. Thickening equipment, with a higher clogging potential, results in higher wash water flowrate and pressure requirements. However, water consumption will also vary from location to location, depending on several influent sludge characteristics. For example, sludge with higher grease content is likely to result in greater rates of water consumption. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-51 The water used to maintain filter porosity can include recycled plant water, recycled filtrate, or municipal non-potable water. Table 5-25 summarizes ranges of typical water consumption for each technology based on industry experience, literature review, and vendor websites. Table 5-25. Sludge Thickening Water Consumption Comparison Technology gpm psi GBT 50 – 65 55 – 70 Disc Thickener 12.2 43.5 RDT 5 - 15 30 – 100 Screw Press 22.5 50 Volute Thickener - - Centrifuge 35 – 70 40 – 60 Unattended Operation The existing DAFT system does not require full time operator attention. The routine maintenance and operation requirements are low enough so the DAFT can dependably run for approximately six hours a day. The City does not typically operate the unit for extended periods of time unattended. The goal for implementation of the selected thickening technology is to maintain a similar level of required attention or better. Tools contributing to this effort include SCADA/HMI systems for easy and remote adjustments, signals and alarms to stop the unit in case of extenuating circumstances, and self- cleaning systems. In order to minimize operator attention requirements, a sludge thickening system with a simple operational scheme will be selected so limited specialized maintenance is required. Table 5-26 presents an evaluation of the alternative technologies considered for unattended operation. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-52 Table 5-26. Sludge Thickening Unattended Operation Comparison Parameter DAFT Unit Disc Thickener RDT Screw Press Volute Thickener GBT Centrifuge Daily Maintenance Startup and shut down, equipment quality checks, polymer system adjustments, performance tests, general housekeeping, check the pump and drives for overheating or unusual noise/vibration, and check for loose parts Routinely check the unit for overflow conditions, startup and shutdown, routinely clean the screen and nozzles, check for loose parts, lubrication, and polymer system maintenance Startup and shut down, equipment quality checks, polymer system adjustments, performance tests, general housekeeping, check the drives for overheating or unusual noise/vibration, and check for loose parts Startup and shutdown, checks for loose parts, equipment quality checks, lubrication, and performance tests Lubrication, checks for loose parts, performance checks, and polymer system maintenance 45 minute belt wash, clean spray nozzles, check oil level in the hydraulic unit/air compressor, extend/retract tension cylinder to clean and oil rods, inspect all alarms and trip cord, and check for loose parts Startup, shutdown, lubrication, checks for loose parts, and performance checks Monthly Maintenance Check wearing on the Ultra High Molecular Weight Polyethylene (UHMWPE) plow parts on the unit, and replace if necessary. Check pump wear and replace when necessary. Check wearing on the Ultra High Molecular Weight Polyethylene (UHMWPE) plow parts on the unit, and replace if necessary Clean the drum screen and flush nozzles, and check the oil levels Weekly cleanings, checks on influent flow to maintain solids plug Clean the drum, replace parts that have worn down Manually clean the belt with soap/bleach, and inspect the belt seam wires for breaks Check flow of oil to the bearings, oil temperature, machine vibration, ammeter reading, bearing temperatures, centrate quality, and scroll drive torque Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-53 Parameter DAFT Unit Disc Thickener RDT Screw Press Volute Thickener GBT Centrifuge Other DAFT Unit startup after power outage requires operator attention to assure pressurization and air aspiration are working correctly. Unit has tendency to overflow if subjected to higher solids content/ loading rates. In this case, the system must be shut down, drained, and the screen cleaned in order to resume normal operation. Four variables the operator may adjust to optimize sludge thickening in response to fluctuating influent characteristics are sludge feed rate, polymer feed rate, the drum incline angle, and the drum speed. A solids plug must be maintained, or else the unit should be shut down and a new plug fabricated with organic material. Initial adjustments to loading on the back-pressure plate may be necessary until the TS concentration and flow rate remain consistent. Little maintenance requirements due to various sensors that will detect and alert unit failure. Semiannually, clean/replace the hydraulic filter screen, replace the drive unit oil, lubricate bearings, clean polymer mixer and injection ring assembly, and replace belt seam wires Little maintenance requirements due to various sensors that will detect and alert unit failure. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-54 Additional Technical Comparison A comparative technical evaluation of the sludge thickening technologies is included in Table 5-27. This comparison gives a brief overview of some of the key differences between WAS thickening technologies. Based on this evaluation the screw press, gravity belt thickener, and centrifuge were eliminated from further evaluation. The screw press was eliminated mainly due to very few installations in WAS thickening applications. Footprint and water consumption were reasons the gravity belt thickener was eliminated. The centrifuge was eliminated due to a large power and water demand. Therefore, only the following technologies were evaluated further: DAFT, disc thickener, RDT, and volute thickener. Table 5-27. Sludge Thickening Alternatives Comparison Parameter DAFT Disc Thickener RDT Screw Press Volute Thickener GBT Centrifuge Strengths Proven Technology, capable of continuous operation Low energy consumption Well proven technology, ease of operation Low energy consup- tion Low energy/ water usage, pilot tested Low energy consump- tion Low polymer usage, compact footprint Weaknesses High energy consumption, large space requirement with no room for unit redundancy Proprietary technology, difficult maintenance Higher polymer usage than current dose Limited applica-tions in WAS thicken-ing, large footprint Newer technology, fewer installations Large space require-ments, open to wet environ-ment High energy usage, high capital costs Solids Capture 98% 98% 98% 97% 97% 98% 98% TWAS Concentration 4-6% 6% 5 – 7% 4 – 9% 4 – 10% 4 – 13% 4 – 10% Polymer Use Expected (lb active/DT) 6-10 11 – 13 7.5 6 – 10 8 – 15 13 2.6 Energy Use (HP) 25 1.25 3 1.5 4 8 150 Unit Footprint (length x width) 9’-0” x 34’-0” 17’8” x 10’ 14’2” x 7’1” 20’ x 4’ 11’10” x 4’10” 23’3” x 12’1” 19’2” x 4’4” 5.13.10 Alternative Costs Table 5-28 presents costs for Sludge Thickening Alternatives SKT 2, SKT 4, SKT 5, and SKT 7. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-55 Table 5-28. Sludge Thickening Alternative Costs Alternative Construction Cost Estimate 1,2 STK 2: New DAFT System $ 2,246,0003 STK 4: Disk Thickener $ 2,789,0004 STK 5: RDT $ 1,303,0003 STK 7: Volute Thickener $ 1,715,0003 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 3. Assumes two units with second unit being redundant 4. Assumes three units with third unit being redundant 5.13.11 Recommended Alternative Table 5-29 presents scoring for Sludge Thickening alternatives. While the no action alternative SKT 1 consists of no expenditures, it hinders facility operations. New DAFT units would be costly to install and would still require a large footprint for the tanks. Additionally, the number of installations of self-aspirating pumps on municipal DAFT units is limited. Alternative STK 4, disk thickener, scored low and has the highest cost estimate. Alternatives SKT 5 (RDT) and SKT 7 (volute thickener) both scored high in the evaluation. A number of regional wastewater facilities have RDTs and the reported performance of the equipment after many years of operation has been positive. The volute thickener would function similar to existing volute press used for dewatering and a benefit would be familiarity to operations staff. Both alternatives would have comparable life cycle costs. Either alternative could be selected, but Alternative SKT 5 is recommended due to an estimated lower cost. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-56 Table 5-29. Sludge Thickening Alternatives Scoring Evaluation Criteria SKT 1 SKT 2 SKT 4 SKT 5 SKT 7 Construction Cost 3 1 1 2 2 Future Flexibility 3 2 2 2 2 O&M Requirements 1 2 2 3 3 Implementation 3 2 1 2 2 Operational History 1 2 2 3 3 City Staff Preference 1 2 2 3 3 Sustainability 1 2 2 3 3 Noise or Odor Potential 1 2 2 3 3 Total 14 15 14 21 21 5.14 Biosolids Dewatering/Disposal (BDD) Alternatives The City would like to compare dewatering equipment that can produce a Class A biosolids product with a composting facility. Alternatives considered for Biosolids Dewatering/Disposal are as follows: Alternative BDD 1: No Action Alternative BDD 2: Composting Facility Alternative BDD 3: Class A Biosolids Dewatering Equipment 5.14.1 Alternative BDD 1: No Action Under this alternative the City would continue to haul dewatered biosolids to Glacier Gold Composting Facility and Flathead County Landfill. The City is approaching the contractual limit at the composting facility and a formal contract with Flathead County for disposal at the landfill does not exist. This alternative leaves the City in a precarious situation for long-term biosolids disposal. 5.14.2 Alternative BDD 2: Composting Facility A City owned and operated composting facility is described in the 2018 Biosolids Management Plan and was summarized in Section 4.3.15 of Chapter 4. Implementation of a composting facility was suggested to be phased so City staff could slowly transition away from current biosolids disposal activities. For the purposes of this evaluation and cost development, all biosolids produced within the planning period are assumed to be handled at the proposed composting facility. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-57 5.14.3 Alternative BDD 3: Class A Biosolids Dewatering Equipment Alternative BDD 3 includes removal of the belt filter press and volute press, installation of Class A biosolids dewatering equipment, and construction of a dewatered biosolids storage area for distribution. This type of dewatering equipment requires chemical addition, flocculation, thickening, and heat treatment to produce a Class A product. The equipment was piloted at AWWTP in the fall of 2013 as part of the biosolds dewatering project. The equipment yielded Class A biosolids but not was not selected due to a large footprint. Removal of both belt filter presses would have been required which was not an objective at the time. 5.14.4 Alternative Costs Table 5-30 presents costs for Biosolids Dewatering/Disposal Alternatives BDD 2 and BDD 3. The cost for Alternative BDD 2 does not include purchasing land for the composting facility, i.e., the facility would be constructed on property already owned by the City or property would be purchased or leased separately. Similarly, the biosolids storage and distribution building required for Alternative BDD 3 would be constructed on property already owned by the City. Table 5-30. Biosolids Dewatering/Disposal Alternatives Costs Alternative Construction Cost Estimate 1,2 BDD 2: Composting Facility $ 5,438,000 BDD 3: Class A Biosolids Dewatering Equipment $ 4,401,000 1. All cost estimates are in late-2018 dollars. Estimates should be escalated to the mid-point of construction for budgeting purposes. 2. Costs include allowances for construction contingency, which accounts for unknown bidding climates, weather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. 5.14.5 Recommended Alternative Table 5-31 presents scoring for the Biosolids Dewatering/Disposal alternatives Although Alternative BDD 2 has the highest estimated construction cost, it scored the highest. A City owned and operated composting facility gives the City direct, long-term control of its biosolids disposal methods. The City has recently conducted specific oxygen uptake requirement (SOUR) tests on its sludge and the results should be considered in the design of a composting facility. The no action alternative has the second highest score but does not address future biosolids management issues. Alternative BDD 3 had the lowest overall score in the evaluation. Primary reasons for the low score are high O&M costs associated with the technology, unknown public perception of production of a Class A biosolids in this manner, and recent investment in dewatering equipment. The Class A biosolids dewatering equipment requires steam and lime addition to produce a Class A product. Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-58 The process leads to increased operation and maintenance costs compared to Alternative BDD 2. Additionally, in regards to ultimate removal or hauling of the dewatered biosolids, it is unknown if the general public will perceive the product in the same way as compost material. Finally, the City has made recent investments in its existing biosolids dewatering equipment, equipment that would be removed and demolished if Alternative BDD 3 were selected. Having two different biosolids technologies is beneficial in that the belt filter press can be used for high solids loading conditions and the volute press can be used for slow, continuous dewatering. Alternative BDD 2 is recommended for implementation. Table 5-31. Biosolids Dewatering/Disposal Alternatives Scoring Evaluation Criteria BDD 1 BDD 2 BDD 3 Construction Cost 3 1 2 Future Flexibility 3 2 1 O&M Requirements 2 2 1 Implementation 3 2 1 Operational History 2 3 1 City Staff Preference 1 3 2 Sustainability 1 3 2 Noise or Odor Potential 2 2 1 Total 17 18 11 5.15 Miscellaneous Improvements Discussions with wastewater treatment plant operations staff and management revealed a number of miscellaneous improvements, renewal and replacement needs, and maintenance items that should be considered as a part of this facility plan. These items will ensure equipment is protected and make the facility more efficient, increasing efficiencies so that critical operations and maintenance tasks can be attended to in a timely manner. Budget should be allocated for these items during the planning period. A summary of costs for all miscellaneous improvements or recommended items is provided in Table 5-32. 5.15.1 Aeration Blower Evaluation Study An evaluation of the existing aeration blowers is recommended as newer technologies are available that are more energy efficient and have a smaller footprint. Aeration within a biological nutrient removal facility is large portion of the electrical costs, so reducing Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-59 those costs within an effective payback period would be beneficial. Funding and rebate programs are available within the industry. 5.15.2 Sidestream Treatment Sidestream treatment consists of reducing nutrient levels in liquid streams (sidestreams) that are a byproduct of biosolids dewatering. These liquids are treated prior to reintroduction with main process flow(s). Sidestream treatment can reduce energy and chemical costs and improve the performance and reliability of existing nutrient removal processes. 5.15.3 Biofilter Bed Rehabilitation Rehabilitation of the perimeter area around the biofilter beds is required as irrigation water that is offset from the side of the bed has resulted in the sides of the bed sloughing. This work would be recommended when the media is replaced. 5.15.4 Chemical Room Modifications Enlarging the chemical room will be required to accommodate planned expansion necessary for the chemical feed equipment. 5.15.5 Standby Power for Aeration Blowers and Critical Facility Equipment A designated standby generator for the aeration blowers and designated standby generator for critical facility equipment is recommended. 5.15.6 Administration/Laboratory Building Expansion An expansion of the administration and laboratory building during the planning period would be necessary as additional processes are added to the facility and corresponding staff would be required. 5.15.7 Digester Chemical Feed System The addition of a chemical feed system in the Digester Control Building would facilitate digester operation and mitigate foaming issues. 5.15.8 Fermenter & VFA Pipeline Condition Assessment The fermenter tank is due to be taken out of service and inspect the coatings that were applied over ten years ago and interior mechanical components. An assessment of the fermenter will determine existing conditions and inform the City of any necessary remedial work. While the fermenter is out of service the VFA pipeline to the bioreactor will be inspected. Costs would include disposal of fermenter contents, necessary inspection equipment, inspection activities, and conditions assessment report. 5.15.9 Effluent Management Plan A comprehensive effluent management plan is recommended to address the intricate public/private interface with effluent management and the complex regulations and legal Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-60 issues surrounding water quality and water rights. The plan should be completed prior to implementing alternative effluent management strategies. 5.15.10 Replace Belt Filter Press The existing belt filter press will be demolished and removed. A new 2-meter wide belt filter press will be installed. 5.15.11 Effluent Temperature Mitigation Plan An effluent temperature mitigation plan should be developed in anticipation of future regulations regarding impacts of the AWWTP on the temperature in Ashley Creek. 5.15.12 Influent Piping and Diversion Structure Rehabilitation The AWWTP influent piping and diversion structure are experiencing corrosion and are in need of rehabilitation. Table 5-32. Miscellaneous Improvements Cost Summary Description Cost Aeration Blower Evaluation Study $20,000 Sidestream Treatment $1,400,000 Biofilter Bed Rehabilitation $50,000 Chemical Room Modifications $250,000 Additional Standby Power for Equipment $1,500,000 Administration/Laboratory Building Expansion $750,000 Digester Chemical Feed System $75,000 Fermenter Condition Assessment $50,000 Effluent Management Plan $50,000 Replace Belt Filter Press $400,000 Effluent Temperature Mitigation Plan $55,000 Influent Piping and Diversion Structure Rehabilitation $180,000 5.16 Recommended Wastewater Treatment Facility Improvements Moving forward with improvements to the facility in a multi-phased approach, addressing the most critical improvements first, is recommended. Based on the evaluation of the Kalispell AWWTP 2018 Facility Plan Update Chapter 5 – Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-61 alternatives in this chapter, the implementation of the alternatives listed below is recommended. The alternatives will be prioritized and assigned a timeline in Chapter 6. • Preliminary Treatment o Alternative INS 3 – Install New Alternative Influent Screen Manufacturers • Influent Pumping Station o Alternative INP 2 – Replace Two Existing Influent Pumps with Higher Capacity Pumps • Primary Clarification o Alternative PCL 3 – Construct Two, 75-FT Diameter Primary Clarifiers • Flow Equalization Basin o Alternative EQB 2 – Construct new EQ Basin to be converted to a Primary Clarifier in the future • Secondary Treatment o Alternative SCT 2 – Convert Secondary Treatment System to a 5-stage process • Secondary Clarification o Alternative SCL 3 – Install Flat Covers on Secondary Clarifiers • Effluent Filtration o Alternative EFF 2 – Construct Tertiary Membrane Filtration (TMF) process • Reaeration Basin o Alternative RAB 2 – Modify Existing Reaeration Basin and Cover Structure • Anaerobic Digestion o Alternative AND 2 – Replace Existing Heat Exchanger, Install Second Heat Exchanger, and Replace Existing Sludge Recirculation Pumps o Alternative AND 3 – Construct Second Primary Digester • Sludge Thickening o Alternative SKT 5 – Replace Existing DAFT Units with Rotary Drum Thickeners (RDTs) • Biosolids Disposal o Alternative BDD 2 – Construct City Owned and Operated Composting Facility • Miscellaneous Improvements as Designated by the City: o Aeration Blower Evaluation Study Kalispell AWWTP 2018 Facility Plan Update Chapter 5 - Wastewater Treatment Facility Improvement Alternatives and Evaluations Page 5-62 o Sidestream Treatment o Biofilter Bed Rehabilitation o Chemical Room Modifications o Additional Standby Power for Equipment o Administration/Laboratory Building Expansion o Digester Chemical Feed System o Fermenter Condition Assessment o Effluent Management Plan o Replace Belt Filter Press o Effluent Temperature Mitigation Plan o Influent Piping and Diversion Structure Rehabilitation CHAPTER 6 RECOMMENDED ALTERNATIVES AND IMPLEMENTATION PLAN Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page i Contents Recommended Alternatives and Implementation Plan .................................................................... 6-1 6.1 Introduction ............................................................................................................................. 6-1 6.2 Recommended Improvements and Estimated Costs ............................................................. 6-1 6.2.1 Prioritization of Recommendations ........................................................................... 6-1 6.2.2 Timing and Classification of Recommended Improvements ..................................... 6-2 6.2.3 Engineering, Legal, and Administration .................................................................... 6-2 6.3 Implementation of Recommended Improvements ................................................................. 6-3 6.4 Operational Requirements and Impact on Existing Facilities ................................................. 6-7 6.5 Implementation Steps and Schedule ..................................................................................... 6-7 6.6 Financial Requirements .......................................................................................................... 6-8 6.6.1 Cost of Improvements Program ................................................................................ 6-8 6.6.2 Capital Improvement Program .................................................................................. 6-9 6.6.3 Financing and Rate Impacts ..................................................................................... 6-9 6.7 Funding Sources .................................................................................................................... 6-9 6.7.1 Federal and State Funding Sources ......................................................................... 6-9 6.7.2 Local Funding Sources............................................................................................ 6-15 6.7.3 Revenue Bonds ....................................................................................................... 6-15 6.7.4 General Obligation Bonds ....................................................................................... 6-16 6.7.5 Capital Reserves or Cash Basis ............................................................................. 6-16 6.8 Financial Plan ....................................................................................................................... 6-16 Tables Table 6-1. Capital Improvement Projects Schedule: Short-term (FY 19/20 to FY 23/24) ......................... 6-4 Table 6-2. Capital Improvement Projects Schedule: Near-term (FY 24/25 to FY 33/34) .......................... 6-5 Table 6-3. Capital Improvement Projects Schedule: Long-term (FY 34/35 to FY 38/39) .......................... 6-6 Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page ii This page is intentionally left blank Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-1 Recommended Alternatives and Implementation Plan 6.1 Introduction The primary goal of this planning effort was to develop recommended facility improvements that can be implemented within a flexible plan that can be responsive to changing criteria and the City’s available resources. The implementation plan presented below is for improvements recommended to occur within the 2038 planning horizon. The recommended implementation plan is designed to provide timely construction of the necessary improvements at the AWWTP, without creating an overly complex construction management program. The purpose of this chapter is to discuss implementation of recommended improvements to the City of Kalispell AWWTP. The following items are included in this chapter: • Prioritization of recommendations identified in Chapter 5, • Estimates of probable construction costs escalated to the anticipated year of construction, • Engineering design and construction service fees (where applicable), • An implementation plan in the form of a capital improvement schedule, and • A summary financial plan for project implementation 6.2 Recommended Improvements and Estimated Costs 6.2.1 Prioritization of Recommendations The City of Kalispell has limited resources to invest in public works infrastructure, making prioritization of capital improvement projects a necessity. Multiple criteria govern the prioritization of capital improvement projects. The following list highlights the criteria that were used for prioritizing capital improvements at the wastewater treatment facility: • Groundwater Protection • Surface Water Protection • Protection of Public Health • Treatment System Reliability • Service Area Growth • Renewal and Replacement • Regulatory Compliance Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-2 6.2.2 Timing and Classification of Recommended Improvements Chapter 4 analyzed treatment plant capacity and system deficiencies in detail. Chapter 5 evaluated alternatives to address deficiencies and identified recommended improvements. Improvements using a stepped approach is recommended. For the purposes of this plan, three time periods are defined: 1. Short-term: 0 – 5 years (2018 – 2023) 2. Near-term: 5 – 15 years (2023 – 2033) 3. Long-term: 15 – 20 years (2033 – 2038) Recommended improvements fall into one or more of the following three project categories: 1. Renewal and Replacement Projects o Replacement of equipment that is at the end of its useful life o Miscellaneous improvements that would improve operations and maintenance of the facility 2. Growth Related Capital Projects o Capacity expansion of equipment or processes that approach their capacity limit within the planning horizon 3. Regulatory Required Projects o Improvements that are required to meet current or anticipated regulatory requirements Table 6-1 and Table 6-2 below presents timing of projects by fiscal year within the short- term, near-term, and long-term time periods. A classification of recommended improvements is also assigned. 6.2.3 Engineering, Legal, and Administration Overall project costs include the total construction costs, but also an additional markup to estimate the costs of engineering design, construction contracting, construction management, project administration, and legal costs. Legal services often are required to coordinate construction efforts with the local governmental agencies, to facilitate permitting, and interagency coordination. Similarly, ancillary engineering services will be required, such as special investigations, surveys, geotechnical reports, location of interfering utilities, detailed design, preparation of plans and specifications, construction inspection and materials testing, startup assistance, and O&M manual preparation. These potential fees for legal and ancillary engineering services were not included in the base construction cost estimates presented in Chapter 5. An administrative effort (project management) will also be required to coordinate the engineering and legal efforts of all projects. A factor of 30 percent has been added to base construction costs to account for engineering, legal, permitting, and administrative costs for projects described in this report, of which engineering fees comprise approximately 20 percent of the amount. Construction cost projections are made at stated escalation rates. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-3 6.3 Implementation of Recommended Improvements Table 6-1 provides a summary of recommended projects for fiscal year 19/20 to fiscal year 23/24, short-term projects. Table 6-2 provides a summary of recommended projects for fiscal year 24/25 to fiscal year 33/34, near-term projects. Table 6-3 provides a summary of recommended projects for fiscal year 34/35 to fiscal year 38/39, long-term projects. Where applicable, engineering design service fees are also included. A site plan showing location and timing of facility improvements is included in Appendix C. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-4 Table 6-1. Capital Improvement Projects Schedule: Short-term (FY 19/20 to FY 23/24) Alternative Short-term Total Project Costs Project Classification FY 19/20 FY 20/21 FY 21/22 FY 22/23 FY 23/24 EQB 2: Construct new EQ Basin to be converted to a Primary Clarifier in the future $196,000 Engineering $2,349,000 Construction $2,545,000 Growth SCT 2: Convert Bioreactor to 5-stage System $118,000 Engineering $1,531,0001 Regulatory SCL 3: Install Dome Clarifier Covers $403,000 Engineering $3,199,000 Phase 1 Construction2 $1,621,000 Phase 2 Construction3 $5,223,000 Renewal & Replacement RAB 2: Reaeration Basin Modifications $32,000 Engineering $405,0004 Regulatory STK 5: Install Rotary Drum Thickeners $152,000 Engineering $1,813,000 Construction $1,965,000 Renewal & Replacement BDD 2: Composting Facility $631,000 Engineering $7,565,000 Construction $8,196,000 Renewal & Replacement, Growth Misc: Aeration Blower Evaluation Study $22,000 Engineering $22,000 Renewal & Replacement Misc: Biofilter Bed Rehabilitation $6,000 Engineering $70,000 Construction $67,000 Renewal & Replacement Misc: Chemical Room Modifications $29,000 Engineering $348,000 Construction $377,000 Renewal & Replacement, Growth Misc: Fermenter & VFA Pipeline Condition Assessment $52,000 Engineering $52,000 Renewal & Replacement Misc: Effluent Management Plan $57,000 Engineering $57,000 Growth, Regulatory Misc: Effluent Temperature Mitigation Plan $60,000 Engineering $60,000 Regulatory Misc: Influent Piping & Diversion Structure Rehabilitation $50,000 Engineering $150,000 Construction $200,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs $248,000 $453,000 $82,000 $875,000 $150,000 Total Fiscal Year Construction Costs N/A $2,349,000 $3,349,000 $1,621,000 $9,796,000 Total Fiscal Year Costs $248,000 $2,802,000 $3,431,000 $2,496,000 $9,946,000 1. Construction cost = $1,413,000 in FY 24/25. See Table 6-2. 2. Cost for covering Secondary Clarifiers 1 and 2 3. Cost for covering Secondary Clarifier 3 4. Construction cost = $373,000 in FY 24/25. See Table 6-2. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-5 Table 6-2. Capital Improvement Projects Schedule: Near-term (FY 24/25 to FY 33/34) Alternative Near-term Total Project Costs Project Classification FY 24/25 FY 25/26 FY 26/27 FY 27/28 FY 28/29 FY 29/30 FY 30/31 FY 31/32 FY 32/33 FY 33/34 INS 3: Two New Influent Screens $166,000 Engineering $1,991,000 Construction $2,157,000 Renewal & Replacement PCL 3: Convert Existing Primary Clarifiers to EQ; Two new 75–FT Circular Primary Clarifiers $624,000 Engineering $7,484,000 Construction $8,108,000 Growth SCT 2: Convert Bioreactor to 5-stage System $1,413,000 Construction $1,531,0001 Regulatory EFF 2: Tertiary Membrane Filtration $2,492,000 Engineering $29,900,000 Construction $32,392,000 Growth, Regulatory RAB 2: Reaeration Basin Modifications $373,000 Construction $405,0002 Regulatory AND 2: Anaerobic Digestion Equipment Replacement $112,000 Engineering $1,336,000 Construction $1,448,000 Renewal & Replacement AND 3: Add Second Primary Digester $553,000 $6,635,000 Construction $7,188,000 Renewal & Replacement Misc: Sidestream Treatment $194,000 Engineering $2,326,000 Construction $2,520,000 Growth, Regulatory Misc: Additional Standby Power $221,000 Engineering $2,644,000 Construction $2,865,000 Renewal & Replacement Misc: Digester Chemical Feed System $10,000 Engineering $111,000 Construction $121,000 Renewal & Replacement Misc: Replace Belt Filter Press $50,000 Engineering $590,000 Construction $640,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs $60,000 N/A N/A $278,000 $3,239,000 $624,000 $221,000 N/A N/A N/A Total Fiscal Year Construction Costs $1,786,000 $701,000 N/A N/A $3,327,000 $38,861,000 $7,484,000 $2,644,000 N/A N/A Total Fiscal Year Costs $1,846,000 $701,000 N/A $278,000 $6,566,000 $39,485,000 $7,705,000 $2,644,000 N/A N/A 1. Engineering cost = $118,000 in FY 23/24. See Table 6-1. 2. Engineering cost = $32,000 in FY 23/24. See Table 6-1. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-6 Table 6-3. Capital Improvement Projects Schedule: Long-term (FY 34/35 to FY 38/39) Alternative Long-term Total Project Costs Project Classification FY 34/35 FY 35/36 FY 36/37 FY 37/38 FY 38/39 INP 2: Install Two New Influent Pumps $46,000 Engineering $548,000 Construction $594,000 Growth Misc: Administration/Laboratory Building $136,000 Engineering $1,626,000 Construction $1,762,000 Renewal & Replacement Total Fiscal Year Engineering Design Costs N/A $46,000 N/A $136,000 N/A Total Fiscal Year Construction Costs N/A N/A $548,000 N/A $1,626,000 Total Fiscal Year Costs N/A $46,000 $548,000 $136,000 $1,626,000 Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-7 6.4 Operational Requirements and Impact on Existing Facilities Some improvements recommended during the planning period will impact operations during construction, however; the improvements can be made while the existing processes are in operation with only minor shut downs to make process interconnections. A carefully developed construction phasing plan will be required and will be developed as part of the Basis of Design report produced during the design phase. Coordination issues, while critically important, are regularly addressed in similar facility upgrades. Major proposed improvements include addition to or upgrade of the existing treatment processes that are consistent with the capabilities of the current staff. All recommended improvements are anticipated to have a positive impact on the existing AWWTP. 6.5 Implementation Steps and Schedule The decision to proceed with facility improvements needs to occur several years prior to the preferred construction completion date. This is due to the long lead time for financing, design, bidding, and construction. Should the City desire to obtain State Revolving Fund (SRF) loan funds for planning, design, and construction, several years additional time may be necessary. Improvements are currently presented in the schedule as individual standalone projects, but options exist for grouping of recommended improvements into larger construction packages. For example, design of the new EQ basin (EQB 2) and secondary clarifier covers (SCL 3) could be concurrent. Construction for these two improvement elements could likewise occur at the same time. The final grouping of improvements will be as elected by the City, but the approach should allow the City to provide the necessary improvements without creating an overly complex construction management program. After review and Council approval of the plan presented in this report, final selection of the preferred alternative(s), and approval of the design concept by MDEQ, it will be necessary to implement the following steps in order to construct the recommended facilities: 1. Grant/Loan Application(s) a. The City will need to budget for and/or secure financing for design and construction of the improvements. It is possible that state or federal grants may be available to assist the City with the recommended improvements, however; it should be noted that projects that are growth related do not typically rank high for grant assistance. Low-interest loans are available for the improvements recommended through several federal and state sources. 2. Completion of Final Plans and Specifications a. The City’s engineering consultant will need to develop plans and specifications for the projects. 3. Finalize Financing Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-8 a. During the design phase, the City will need to finalize financing arrangements for the construction phase and modify user charges, if necessary. 4. Bid Advertisement a. Advertise for construction bids after MDEQ and City approval of plans and specifications 5. Review Bids a. Receive and review the construction bids submitted for the project. After determination of the responsible low bidder, all contract documents would be submitted to MDEQ and/or other funding agencies for their review and concurrence of the award of a construction contract. 6. Award Construction Contract a. Award the construction contract and authorize the responsible low bidder to begin construction. 7. Construction a. During construction, the City and their consultant must maintain proper financial records of the project, process partial payments, process change orders, and provide needed staff for the facility. b. Other tasks that must usually be accomplished during this phase include finalization of the plan of operation, submittal of a draft O&M manual and final O&M manual, and obtain approval of the wastewater user rate ordinances. c. After completion of the construction project, arrange for final inspections, certification of the facility, and final payment(s) from grant or loan agencies. Implementation of the proposed improvements will require a significant amount of coordination between the City, the engineering and financial consultants, MDEQ, and other funding agencies. Improvements that are minor in nature can likely be accomplished by City staff. 6.6 Financial Requirements The purpose of this section is to address financial planning to implement the recommendations of the facility plan. Potential outside funding sources are discussed in Section 6.7, including federal and state loans and grants. 6.6.1 Cost of Improvements Program Chapter 5 presented a summary of estimated capital costs for a variety of alternative wastewater management improvements. These are preliminary, planning level costs and are subject to change as the implementation process proceeds and facility requirements become further refined through more detailed engineering. Alternatives Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-9 were evaluated in that chapter in order to assess the relative strengths and weaknesses of each option and recommendations were made with regard to improving the City’s wastewater treatment facilities. This chapter outlined the recommended plan and presented a schedule for implementing the plan. The financial impact resulting from the recommended capital improvement plan must be evaluated so that a financial plan can be developed that provides adequate funding for implementation of program elements. 6.6.2 Capital Improvement Program A scheduled plan for implementing capital improvements to the City’s AWWTP was presented in Table 6-1 and Table 6-2. Each table also summarizes the total recommended capital improvement and engineering cost by year. 6.6.3 Financing and Rate Impacts The City’s existing wastewater system is funded through user charges which pay for on- going operations and maintenance expenses and modest facility improvements. An evaluation of potential changes in residential sewer rates has not been included as part of this facility plan update. The City currently has a request for qualifications for consultant services to conduct a water and wastewater rate study. The City will continue to evaluate their rate structures through that separate work effort. 6.7 Funding Sources A key project implementation strategy is the method of funding and financing of recommended improvements. Pursuance of available low-interest loans and grants to offset the cost of the wastewater treatment plant improvement projects is recommended. The following section consists of a detailed discussion on available outside funding sources. 6.7.1 Federal and State Funding Sources In 1995, the state and federal funding agencies that are members of the Water, Wastewater, and Solid Waste Action Coordination Team (W2ASACT) adopted a common preliminary engineering analysis format that would be acceptable to each of the agencies that fund water, wastewater, and solid waste projects in Montana. Due to the success of developing the common engineering format, and in response to recommendations made by local communities and technical assistance providers, some of the Montana State agencies also adopted a common application summary form and environmental checklist. In 1997, all of the state and federal funding agencies involved in W2ASACT worked together to complete the task by adopting a uniform application supplement that contains a common application form, environmental checklist, and preliminary engineering analysis. The following programs have adopted the uniform application process in the State of Montana: • Montana Board of Investments/INTERCAP Program • Montana Department of Commerce/Community Development Block Grant Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-10 (CDBG) Program • Montana Department of Commerce/Treasure State Endowment Program (TSEP) • Montana Department of Environmental Quality (MDEQ) State Revolving Fund (SRF) Loan Programs • Montana Department of Natural Resources and Conservation (DNRC) Renewable Resource Grant and Loan (RRGL) Program • U.S. Department of Agriculture (USDA) Rural Development (RD) Program/Rural Utilities Service State Revolving Funds (SRF) The Montana Legislature established two State Revolving Fund (SRF) Loan Programs - one for water pollution control projects (wastewater and nonpoint source projects) and another for potable water projects. Both programs provide at, or below, market interest rate loans to eligible Montana entities. These programs are funded with capitalization grants from the U.S. Environmental Protection Agency (US EPA) and are matched with State issued general obligation bonds. Combined, these two sources of funds create the “state revolving fund” from which loans are made and borrower repayments revolve to provide loans for future infrastructure projects. The MDEQ is the administering agency and assures that the technical, financial, and programmatic requirements of the program are met. The DNRC issues the State’s general obligation bonds and makes loans to the project borrowers. Cooperatively, MDEQ and DNRC administer the SRF Loan Programs. Applicant Eligibility All entities planning to use SRF funding must contact the MDEQ SRF Loan Program and request that their project(s) be added to the Water Pollution Control (WPC) or Drinking Water (DW) SRF Project Priority List and Intended Use Plan. This annual process begins in July to identify projects which may need SRF funding for their project in the upcoming year. Early notification by the applicant is essential to get on the priority list, and a project remains on the list until it has been completed, regardless of the funding source(s) used to finance the project. Water Pollution Control SRF Loans are made to municipalities (meaning any state agency, city, town, or other public body created pursuant to state law) to finance all, or a portion, of the treatment works project costs or to buy or refinance debt obligations of municipalities. Loans are made to municipalities or private persons (meaning an individual, corporation, partnership, or other non-governmental legal entity) to finance all or a portion of the costs of nonpoint source pollution control projects. Project Eligibility Projects such as wastewater treatment plant improvements, interceptors, collectors, lagoon rehabilitation, lagoons, storm drains, facility plans, project design, inspection, land Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-11 used for treatment purposes and non-point source pollution control projects (including certain solid waste management projects) are eligible. Funding Considerations Water pollution control SRF loans have a current interest rate of 2.5 percent for 20 years. Loan amounts are limited to the borrower’s ability to repay the loan and by the SRF funds which are available for project financing. Loans are required to be secured by a bond or note and revenue bonds require debt service reserve and coverage of 110%. Application Instructions for Public Facility Projects Applicants submit the “Uniform Application Supplement” to request SRF loan funding. These applications are accepted year round and will be evaluated after the preliminary engineering analysis has been submitted to and reviewed by the MDEQ. Loan projects are subject to federal and state laws including environmental reviews, minority business requirements, prevailing wage rates, etc. Applicable facility planning with environmental assessment of the proposed project, plans and specifications, adequate construction management and proper startup and operation of the facilities are requirements of the program. After the application is evaluated and approved, funds can be committed to a project. The SRF loan program cooperates with the other funding programs to ensure project funding is available when it is needed. Community Development Block Grant Program (CDBG) This federal program is funded by the U.S. Department of Housing and Urban Development and administered through the Montana Department of Commerce in Helena, MT. The grant program has a maximum grant amount of $400,000 and is often used for small wastewater capital improvements. Montana's Community Development Block Grant (CDBG) Program is a federally-funded competitive grant program designed to help communities with their most critical community development needs. The program was established by Congress in 1974 and is administered nationally by the U.S. Department of Housing and Urban Development (HUD). By agreement, the Montana Department of Commerce (DOC) administers the CDBG Program for local governments with populations less than 50,000. Under federal law, all CDBG projects must principally benefit low and moderate income persons. In public facility projects, this is accomplished by making improvements to public facilities that serve communities or neighborhoods that are mostly low or moderate income families or by providing services to low or moderate income people. Benefit to low and moderate income families can also be demonstrated by paying for the cost of water meter installation or for the hook-up charges or special assessments for eligible families. Eligible Projects A wide variety of community development projects are eligible for grant funding, divided into three basic categories: (1) Economic Development; (2) Housing and Community Revitalization; and (3) Public Facilities. The Economic Development Category is administered by the Economic Development Division of the Department of Commerce Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-12 (DOC). The Housing and Public Facilities categories are administered by DOC’s Local Government Assistance Division. Montana's CDBG Public and Community Facilities grants help local governments fund construction or rehabilitation of infrastructure and facilities that primarily benefit low- to moderate-income (LMI) Montanans, i.e. individuals earning less than 80% of the area median income. These projects can target LMI residents and provide direct benefits by improving or creating access to suitable living environments or necessary services, or these projects can provide an area-wide benefit to the entire community as long as at least 51% of the project’s beneficiaries are determined to be LMI. Public facilities projects include community facilities such as sewer improvements. Projects can also include those designed to principally serve low and moderate income persons including Head Start centers, mental health centers, centers for abused children, senior centers, and rural hospital/nursing homes. Eligible Applicants Eligible applicants are limited to general purpose local governments: incorporated towns and cities under 50,000 population and counties. Local governments can apply to the Montana Department of Commerce on behalf of private businesses, private nonprofit corporations such as a local economic development corporation, or special purpose governmental agencies such as a housing authority or a water or sewer district. In all cases the local government assumes ultimate responsibility for administration of the federal funds and compliance with all federal and state requirements. Each local government can apply for one housing project and one public facility project each program year. Applications for economic development projects are accepted continuously as long as funding is available. Funding Requirements CDBG provides grants to local governments up to $450,000. For the public facilities category, local governments must provide a match of at least 25% of the CDBG funds requested. The match may be waived in cases of extreme financial hardship and where a serious public health or safety problem exists. In the case of water and sewer projects, analysis of financial need focuses on a community’s projected water and sewer rates measured against the community’s median household income and other economic factors. Projected water and sewer rates are compared to a “target rate” based on local median household income. Application Process Teams composed of DOC staff are appointed to review each application and compare them with the other applications submitted for each category. At the conclusion of the ranking process, written summaries of the review team's comments and conclusions and the recommended ranking scores are submitted to the DOC Director for his consideration. The Director makes the final decision on grant awards. Each applicant can request a copy of the detailed written summary prepared by DOC staff. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-13 Treasure State Endowment Program (TSEP) The Treasure State Endowment Program (TSEP) is a State funded program administered by the Montana Department of Commerce. The program is designed to assist local governments in obtaining affordable financing for specific types of local public facility projects. Eligible Applicants Applicants eligible for TSEP assistance include cities, towns, and counties, as well as, county or multi-county water, sewer, or solid waste districts. Eligible Projects Projects eligible for TSEP assistance include construction or repair of drinking water systems, wastewater treatment facilities, sanitary or storm sewer systems, solid waste disposal and separation systems, and bridges. Funding Requirements TSEP primarily provides matching grants. TSEP grants limits are $750,000 per project, with a local match requirement of 50 percent of the project costs. Local matching funds are public or private funds (cash or loans) that directly support the costs of eligible project activities. The matching funds can include grants from other state or federal programs. However, grant funds are only recommended for water, wastewater and solid waste projects where the applicant’s user rates are at or above a “target rate” based on the community’s median household income, or the applicant does not have the capacity to borrow funds, if below the target rate. In other words, TSEP is a “gap financing” program. Applicants that do not qualify for TSEP grant funds may be recommended for loans from TSEP or other agencies. Application Process TSEP applications are accepted by the Montana Department of Commerce every two years, and are reviewed and approved by the Legislature. Applications are accepted in May of the year before the Legislature meets (even numbered years). The TSEP Application Guidelines provide specific information about the program and all of its requirements. It is important that potential applicants obtain a copy of the guidelines in order to be aware of the requirements of the program and expectations of TSEP applicants. The application materials provided in this supplement need to be completed by all TSEP applicants, and submitted in the format as described in the TSEP Application Guidelines. Intercap Program The INTERCAP Program is a low cost, variable-rate program that lends money to local governments including municipalities for water and sewer projects and county water and sewer districts. The program is administered by the Board of Investments’ (BOI) bond Program Office. The BOI issues tax-exempt bonds and loans the proceeds to eligible borrowers. INTERCAP is an excellent source for interim financing. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-14 Applicant Eligibility Eligible borrowers include political subdivisions of state or local governments. These entities include cities/towns, counties, water and sewer districts, solid waste districts, school districts, rural fire districts, rural fire service areas, special and rural improvement districts, as well as other political subdivisions. Project Eligibility Projects including water, wastewater, and solid waste are eligible for loan funding, as well as preliminary engineering costs. Funding Requirements The term of the loan is limited to 10 years. Except for interim loans, an applicant’s rates and charges usually needs to be set to produce net revenues (revenues less expenses for operation) to cover debt service by a factor of 1.25 times. INTERCAP interest rates change each February 16. Since the Program’s inception, the interest rate has averaged over 5%. Loan principal and interest payments are each February and August 15. Loans made to municipalities and county water and sewer districts for the above mentioned projects are treated as a bond and have annual principal payments. INTERCAP allows 100% financing; no equity or matching money is necessarily required. Application Process INTERCAP applications are accepted on an on-going basis. Loans under $50,000 can be approved by BOI staff. Amounts over $50,000 must be approved by the BOI Board which meets approximately every six weeks. For loans over a one-year term, a 1% origination fee is charged and is rolled into the loan. Funds are released on an on-going basis as the project is completed. Renewable Resource Grant and Loan Program (RRGL) The Montana Legislature established the Renewable Resource Grant and Loan (RRGL) Program to enhance Montana’s renewable resources. Administered by the Resource Development Bureau of the Montana DNRC, the program provides both grant and loan funding for eligible renewable resource and public facility projects. The program is funded through interest accrued on the Resource Indemnity Trust Fund and the sale of Coal Severance Tax Bonds. Applicant Eligibility Grants and Loans to Governmental Entities - Eligible applicants include political subdivisions of state or local government. These entities may include counties, cities, incorporated towns, conservation districts, water and/or sewer districts, school districts, irrigation districts, conservancy districts, joint boards of control, state agencies and state universities. Emergency Grants and Loans Emergency grants limited to $30,000 per application and emergency loans limited by the applicant’s debt capacity are available to governmental entities for projects that require Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-15 immediate attention. Projects must meet the general eligibility requirements for the RRGL Program. Emergency funding is only awarded for projects that, if delayed, will result in substantial damage to public health or the environment or will result in legal liability. Project Eligibility Renewable resource and public facility projects including water, wastewater, and solid waste projects are eligible for grant and loan funding. Projects must enhance the common well-being of Montanans through the conservation, management, development, or protection of renewable resources. Numerous public infrastructure projects for water, wastewater, and solid waste facilities have received funding through this program. Funding is available for preliminary engineering/design as well as construction of projects. Funding Limitations Funding limitations are as follows: • Grants o DNRC limits grant funding recommendations to a maximum of $125,000. • Loans o Loans are normally limited only by the applicant’s debt capacity. Interest rates vary with the Coal Severance Tax Bond market. Interest rate subsidies (decreases from the bond market rate) ranging from one to three percent for the first five years of the loan term are available based on proposed combined user rates. Loan terms are usually limited to 20 years. Application Instructions for Public Facility Projects The RRGL Program accepts applications on or before May 15th of even numbered years. The application materials provided in the Uniform Application Supplement for Montana Public Facility Projects may be used to replace designated sections of the Renewable Resource Grant and Loan Program Application Guidelines and Forms for Governmental Entities. However, the guidelines contain sections that must be completed by all applicants in addition to this supplement. 6.7.2 Local Funding Sources Local funding of capital improvements rely on private financing through bond sales or cash-based financing through use of connection fees or capital reserves. 6.7.3 Revenue Bonds Revenue Bonds are long-term municipal bonds guaranteed solely by the dedication of project income or sewer funds (e.g., user fees) rather than by a general tax. Current interest rates on bonds range from 4 to 4.5 percent. Kalispell AWWTP 2018 Facility Plan Update Chapter 6 – Recommended Alternatives and Implementation Plan Page 6-16 6.7.4 General Obligation Bonds General Obligation Bonds are long-term municipal bonds that are backed by the full faith and credit of the local government, in this case the City of Kalispell. This means the local government pledges to use all of its taxing and other revenue-raising powers to repay bond holders. General obligation bonds require voter approval through a local bond election. 6.7.5 Capital Reserves or Cash Basis Capital improvements may be funded through cash reserves developed through connection and user fees. The obvious advantages of this approach are the avoidance of debt and interest payments. 6.8 Financial Plan As mentioned previously, the City is currently planning to evaluate its rate structure for water and wastewater services. The expected methods of financing the improvements recommended in this plan include the use of cash reserves, revenue bond financing, and the SRF loan program. In order for the City to assure eligibility for the SRF program, concurrence must be obtained from MDEQ on environmental documents prepared and determinations issued by the City. The City would also likely qualify for the RRGL and TSEP programs. Qualifying for the TSEP program would be contingent on the target rate requirements and requirements for the project to solve an urgent or serious health or safety problem or compliance with State or Federal regulations. The target rates established by the Department of Commerce for the City of Kalispell based on 2015 census data are $78.77/month for combined water and wastewater, $47.95/month for water only, $30.82/month for wastewater only and $10.27/month for solid waste. It is unlikely the City would qualify for a Community Development Block Grant due to the low to moderate income requirements. According to the 2015 census data, Kalispell’s percentage of households that are low to moderate income are 43.62%. APPENDIX A MONTANA POLLUTANT DISCHARGE ELIMINATION SYSTEM (MPDES) PERMIT NO. MT 0021938 APPENDIX B COST ESTIMATES Estimate of Probable Construction Cost - Alternative INS 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 15,152$ 15,152$ 3% of other Division costs Demolition 1 LS 5,000$ 5,000$ Modifications to West Channel 1 LS 7,500$ 7,500$ Aluminum Railing 1 LS 5,000$ 5,000$ Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Concrete Coating 1 LS 5,000$ 5,000$ Division 10 -Specialities Identification Devices 1 LS 500$ 500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 125,318$ 125,318$ 33% of Construction Cost Division 40 - Process Interconnections 3/4" PVC Pipe 50 LF 35$ 1,750$ 3/4" PVC Fittings 10 EA 25$ 250$ 3/4" PVC Valves 10 EA 50$ 500$ Float Switch 1 EA 1,250$ 1,250$ Misc. Mechanical 1 LS 2,500$ 2,500$ FSM Perforated Filter Screen 1 LS 266,000$ 266,000$ FSM quote plus 40% installation costs FSM Screenings Wash Press 1 LS 82,000$ 82,000$ FSM quote plus 40% installation costs Subtotal 525,000$ Mobilization, Bonds, and Insurance 5%26,000$ Contractor's Overhead and Profit 10%53,000$ Subtotal 604,000$ Miscellaneous Items and Contingencies 25%151,000$ Total Estimated Construction Cost 755,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative INS 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 24,692$ 24,692$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Modifications to Channels 2 LS 7,500$ 15,000$ Aluminum Railing 1 LS 5,000$ 5,000$ Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Concrete Coating 1 LS 5,000$ 5,000$ Division 10 -Specialities Identification Devices 1 LS 500$ 500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 204,221$ 204,221$ 33% of Construction Cost Division 40 - Process Interconnections 3/4" PVC Pipe 50 LF 35$ 1,750$ 3/4" PVC Fittings 10 EA 25$ 250$ 3/4" PVC Valves 10 EA 50$ 500$ Float Switch 1 EA 1,250$ 1,250$ Misc. Mechanical 1 LS 2,500$ 2,500$ JWCE Monster Fine Screen 2 LS 205,800$ 411,600$ JWCE quote plus 40% installation costs JWCE Monster Wash Press 2 LS 84,000$ 168,000$ JWCE quote plus 40% installation costs Subtotal 858,000$ Mobilization, Bonds, and Insurance 5%43,000$ Contractor's Overhead and Profit 10%86,000$ Subtotal 987,000$ Miscellaneous Items and Contingencies 25%247,000$ Total Estimated Construction Cost 1,234,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative INP 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 27-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 6,109$ 6,109$ 3% of other Division costs Demolition 1 LS 5,000$ 5,000$ Equipment Pad 1.2 CY 500$ 600$ Division 9 - Finishes Concrete Coating 1 LS 5,000$ 5,000$ Division 23 - HVAC HVAC Wet Well Modifications 1 LS 25,000$ 25,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 50,523$ 50,523$ 33% of Construction Cost Division 40 - Process Interconnections 10" Check Valve 2 EA 2,500$ 5,000$ 10" Plug Valve 2 EA 2,500$ 5,000$ Misc. Piping 1 LS 7,500$ 7,500$ Pumps and Motor 2 EA 38,000$ 76,000$ Previous estimate escalated +40% install VFD 2 EA 12,000$ 24,000$ Previous estimate escalated Subtotal 186,000$ Mobilization, Bonds, and Insurance 5%9,000$ Contractor's Overhead and Profit 10%19,000$ Subtotal 214,000$ Miscellaneous Items and Contingencies 25%54,000$ Total Estimated Construction Cost 268,000$ Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Estimate of Probable Construction Cost - Alternative INP 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 27-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 20,804$ 20,804$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Floodplain Permitting 1 LS 15,000$ 15,000$ Pump Vault 50 CY 600$ 30,000$ Core Drilling 1 LS 75,000$ 75,000$ Vault Ladder 1 LS 5,000$ 5,000$ Misc Metal 1 LS 7,500$ 7,500$ Link Seals (Core Drilling)1 EA 5,000$ 5,000$ Sealants and Caulking 1 LS 5,000$ 5,000$ Division 9 - Finishes Valve Vault Coatings 1 LS 50,000$ 50,000$ Division 23 - HVAC HVAC Wet Well Modifications 1 LS 25,000$ 25,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 172,062$ 172,062$ 33% of Construction Cost Excavation and Fill 1 LS 50,000$ 50,000$ Bypass Pumping 1 LS 100,000$ 100,000$ Division 40 - Process Interconnections 18" 90 deg Elbow 2 EA 1,900$ 3,800$ 18" 45 deg Elbow 1 EA 1,500$ 1,500$ 18" Tee 2 EA 2,800$ 5,600$ 18" Ductile Iron Pipe 50 LF 100$ 5,000$ 10" 90 deg Elbow 2 EA 450$ 900$ 10" Tee 2 EA 550$ 1,100$ 10" Ductile Iron Pipe 20 LF 50$ 1,000$ Submersible Pump 3 EA 38,000$ 114,000$ Previous estimate escalated +40% install VFD 3 EA 12,000$ 36,000$ Previous estimate escalated Subtotal 739,000$ Mobilization, Bonds, and Insurance 5%37,000$ Contractor's Overhead and Profit 10%74,000$ Subtotal 850,000$ Miscellaneous Items and Contingencies 25%213,000$ Total Estimated Construction Cost 1,063,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Division 31 - Earthwork Division 7 - Thermal and Moisture Protection Division 33 - Utilities Estimate of Probable Construction Cost - Alternative PCL 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 31-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 89,157$ 89,157$ 3% of other Division costs Demolition 1 LS 35,000$ 35,000$ Grout 1 LS 20,000$ 20,000$ CMU Control Building 1 LS 50,000$ 50,000$ (CDA) escalated and rounded Flow Splitting Structure 1 LS 75,000$ 75,000$ 115 FT diameter Clarifier 1 LS 650,000$ 650,000$ (CDA) escalated and rounded Handrail/Platform/Stairs 1 LS 30,000$ 30,000$ (CDA) escalated Interior Metals 1 LS 54,000$ 54,000$ (CDA) escalated and rounded Misc Metal 1 LS 7,500$ 7,500$ FRP Components 1 LS 20,000$ 20,000$ Sealants and Caulking 1 LS 15,000$ 15,000$ Coatings 1 LS 75,000$ 75,000$ Division 11 - Equipment Clarifier Mechanism 1 EA 415,000$ 415,000$ HVAC 1 EA 95,000$ 95,000$ (CDA) escalated and rounded Electrical & Instrumentation work 1 LS 737,385$ 737,385$ 33% of Construction Cost Shoring for Control Building & Clarifier 1 LS 100,000$ 100,000$ (CDA) escalated and rounded Excavation Control Building 1 LS 130,000$ 130,000$ (CDA) escalated and rounded Backfill Control Building 1 LS 5,000$ 5,000$ (CDA) escalated and rounded Excavation Clarifier 1 LS 105,000$ 105,000$ (CDA) escalated and rounded Backfill Clarifier 1 LS 30,000$ 30,000$ (CDA) escalated and rounded Clarifier Slab Granular Fill 1 LS 82,000$ 82,000$ (CDA) escalated Control Building Slab Granular Fill 1 LS 7,000$ 7,000$ (CDA) escalated and rounded 18" Pipe 100 LF 100$ 10,000$ 30" Pipe 100 LF 700$ 70,000$ Interconnections 1 LS 20,000$ 20,000$ Sludge Pumps 2 EA 42,000$ 84,000$ (Kalispell) plus 40% installation Scum Pumps 2 EA 30,000$ 60,000$ (Kalispell) plus 40% installation Misc. Equipment 1 LS 25,000$ 25,000$ Subtotal 3,096,000$ Mobilization, Bonds, and Insurance 5%155,000$ Contractor's Overhead and Profit 10%310,000$ Subtotal 3,561,000$ Miscellaneous Items and Contingencies 25%890,000$ Total Estimated Construction Cost 4,451,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 7 - Thermal and Moisture Protection Division 31 - Earthwork Division 6 - Wood, Plastics, and Compostites Division 9 - Finishes Division 23 - Heating, Ventilation and Air Conditioning Divison 46 - Water and Wastewater Equipment Division 26 - Electrical Division 40 - Process Interconnections Estimate of Probable Construction Cost - Alternative PCL 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 31-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 87,162$ 87,162$ 3% of other Division costs Demolition 1 LS 50,000$ 50,000$ Grout 1 LS 20,000$ 20,000$ CMU Control Building 1 LS 50,000$ 50,000$ (CDA) escalated and rounded Flow Splitting Structure 1 LS 75,000$ 75,000$ One 75 FT diameter Clarifier 1 LS 425,000$ 425,000$ (CDA) escalated and rounded Handrail/Platform/Stairs 1 LS 30,000$ 30,000$ Interior Metals 1 LS 54,000$ 54,000$ (CDA) escalated and rounded Misc Metal 1 LS 7,500$ 7,500$ FRP Components 1 LS 35,000$ 35,000$ Sealants and Caulking 1 LS 15,000$ 15,000$ Division 9 - Finishes Coatings 1 LS 75,000$ 75,000$ HVAC 1 LS 95,000$ 95,000$ (CDA) escalated and rounded Electrical & Instrumentation work 1 LS 720,885$ 720,885$ 33% of Construction Cost Shoring for Control Building & Clarifier 1 LS 100,000$ 100,000$ (CDA) escalated and rounded Excavation Control Building 1 LS 130,000$ 130,000$ (CDA) escalated and rounded Backfill Control Building 1 LS 5,000$ 5,000$ (CDA) escalated and rounded Excavation Clarifier 1 LS 75,000$ 75,000$ (CDA) escalated and rounded Backfill Clarifier 1 LS 20,000$ 20,000$ (CDA) escalated and rounded Clarifier Slab Granular Fill 1 LS 35,000$ 35,000$ (CDA) escalated Control Building Slab Granular Fill 1 LS 7,000$ 7,000$ (CDA) escalated and rounded 18" Pipe 200 LF 100$ 20,000$ 30" Pipe 200 LF 700$ 140,000$ Interconnections 1 LS 20,000$ 20,000$ Clarifier Mechanism and Weirs 2 EA 270,000$ 540,000$ (CDA) escalated and rounded Sludge Pumps 3 EA 42,000$ 126,000$ (Kalispell) plus 40% installation Scum Pumps 2 EA 30,000$ 60,000$ (Kalispell) plus 40% installation Misc. Equipment 1 LS 25,000$ 25,000$ Subtotal 3,043,000$ Mobilization, Bonds, and Insurance 5%152,000$ Contractor's Overhead and Profit 10%304,000$ Subtotal 3,499,000$ Miscellaneous Items and Contingencies 25%875,000$ Total Estimated Construction Cost 4,374,000$ Division 23 - Heating, Ventilation and Air Conditioning Division 31 - Earthwork Division 40 - Process Interconnections Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 7 - Thermal and Moisture Protection Division 26 - Electrical Division 6 - Wood, Plastics, and Compostites Estimate of Probable Construction Cost - Alternative PCL3 (EQB4) Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 31-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 131,052$ 131,052$ 3% of other Division costs Demolition 1 LS 50,000$ 50,000$ Concrete Clarifier Slab Subgrade 2 EA 120,000$ 240,000$ (CDA) escalated Drill Column Shafts 2 EA 70,000$ 140,000$ Grout 2 EA 20,000$ 40,000$ Modifications to Clarifiers 2 LS 100,000$ 200,000$ Control Building Slab Granular Fill 1 LS 7,000$ 7,000$ (CDA) escalated and rounded CMU Control Building 1 LS 50,000$ 50,000$ (CDA) escalated and rounded Handrail/Platform/Stairs 2 LS 60,000$ 120,000$ Structural/Roofing Metal 1 LS 136,000$ 136,000$ (CDA) escalated and rounded Interior Metals 1 LS 54,000$ 54,000$ (CDA) escalated and rounded FRP Components 1 LS 255,000$ 255,000$ (CDA) escalated FRP Clarifier Slab 2 LS 100,000$ 200,000$ FRP Control Building and Wet Well 1 LS 155,000$ 155,000$ (CDA) escalated and rounded Sealants and Caulking 2 LS 15,000$ 30,000$ Division 11 - Equipment Clarifier Mechanism and Weirs 2 EA 300,000$ 600,000$ Division 13 - Special Construction Instrumentation 2 LS 60,000$ 120,000$ 10% of the Equipment Cost HVAC 1 EA 95,000$ 95,000$ (CDA) escalated and rounded Electrical & Instrumentation work 1 LS 1,016,400$ 1,016,400$ 33% of Construction Cost Shoring for Control Building 1 LS 120,000$ 120,000$ (CDA) escalated and rounded Excavation Wet Well 1 LS 130,000$ 130,000$ (CDA) escalated and rounded Control Building and Wet Well Backfill 1 LS 22,000$ 22,000$ (CDA) escalated and rounded Excavation and Fill 2 LS 50,000$ 100,000$ 18" Pipe 200 LF 100$ 20,000$ 30" Pipe 200 LF 700$ 140,000$ Interconnections 1 LS 20,000$ 20,000$ Flow Splitting Structure 1 EA 75,000$ 75,000$ Sludge Pumps 4 EA 42,000$ 168,000$ (Kalispell) plus 40% installation Scum Pumps 3 EA 30,000$ 90,000$ (Kalispell) plus 40% installation Misc. Equipment 1 LS 25,000$ 25,000$ Subtotal 4,549,000$ Mobilization, Bonds, and Insurance 5%227,000$ Contractor's Overhead and Profit 10%455,000$ Subtotal 5,231,000$ Miscellaneous Items and Contingencies 25%1,308,000$ Total Estimated Construction Cost 6,539,000$ Division 23 - Heating, Ventilation and Air Conditioning Division 26 - Electrical Division 31 - Earthwork Division 40 - Process Interconnections Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 6 - Wood, Plastics, and Compostites Division 7 - Thermal and Moisture Protection Estimate of Probable Construction Cost - Alternative EQB 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 31-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 37,403$ 37,403$ 3% of other Division costs Grout 1 EA 20,000$ 20,000$ 75 FT diameter tank 1 LS 425,000$ 425,000$ (CDA) escalated Handrail/Platform/Stairs 1 LS 30,000$ 30,000$ Misc Metal 1 LS 10,000$ 10,000$ Misc. Carpentry 1 LS 20,000$ 20,000$ (CDA) escalated Sealants and Caulking 1 LS 15,000$ 15,000$ Coatings 1 LS 75,000$ 75,000$ Electrical & Instrumentation work 1 LS 321,750$ 321,750$ 33% of Construction Cost Excavation Clarifier 1 LS 75,000$ 75,000$ (CDA) escalated and rounded Backfill Clarifier 1 LS 20,000$ 20,000$ (CDA) escalated and rounded Shoring for Clarifier 1 LS 50,000$ 50,000$ (CDA) escalated and rounded Clarifier Slab Granular Fill 1 EA 35,000$ 35,000$ (CDA) escalated 18" Pipe 100 LF 100$ 10,000$ 30" Pipe 100 LF 700$ 70,000$ Interconnections 1 LS 20,000$ 20,000$ Washdown and Appurtenances 1 LS 50,000$ 50,000$ Submersible mixers 2 EA 25,000$ 50,000$ Subtotal 1,284,000$ Mobilization, Bonds, and Insurance 5%64,000$ Contractor's Overhead and Profit 10%128,000$ Subtotal 1,476,000$ Miscellaneous Items and Contingencies 25%369,000$ Total Estimated Construction Cost 1,845,000$ Division 9 - Finishes Division 26 - Electrical Division 40 - Process Interconnections Divison 46 - Water and Wastewater Equipment Division 31 - Earthwork Division 1 - General Requirements Division 7 - Thermal and Moisture Protection Divison 3 - Concrete Divison 5 - Metals Division 6 - Wood, Plastics, and Compostites Estimate of Probable Construction Cost - Alternative EQB 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 27-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 8,030$ 8,030$ 3% of other Division costs Demolition 1 LS 75,000$ 75,000$ Wall addition 115 CY 750$ 86,250$ Railing 1 LS 10,000$ 10,000$ Misc Metal 1 LS 5,000$ 5,000$ Sealants and Caulking 1 LS 10,000$ 10,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 66,413$ 66,413$ 33% of Construction Cost Division 40 - Process Interconnections Misc. Interconnections 1 LS 25,000$ 25,000$ Washdown and Appurtenances 1 LS 40,000$ 40,000$ EQ Pumping 1 LS 25,000$ 25,000$ Subtotal 351,000$ Mobilization, Bonds, and Insurance 5%18,000$ Contractor's Overhead and Profit 10%35,000$ Subtotal 404,000$ Miscellaneous Items and Contingencies 25%101,000$ Total Estimated Construction Cost 505,000$ Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 7 - Thermal and Moisture Protection Estimate of Probable Construction Cost - Alternative EQB 4 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 6,948$ 6,948$ 3% of other Division costs Demolition 1 LS 75,000$ 75,000$ Modifications to Clarifiers 1 LS 100,000$ 100,000$ Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Concrete Coating 1 LS 50,000$ 50,000$ Division 10 -Specialities Identification Devices 1 LS 500$ 500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 38,600$ 38,600$ 20% of Construction Cost Washdown and Appurtenances 1 LS 35,000$ 35,000$ Subtotal 314,000$ Mobilization, Bonds, and Insurance 5%16,000$ Contractor's Overhead and Profit 10%31,000$ Subtotal 361,000$ Miscellaneous Items and Contingencies 25%90,000$ Total Estimated Construction Cost 451,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative SCT 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 23-Jan-19 Project No.10111714 Estimator R. Schultz Task Alternatives Eval Checked By C. Caprara Task No.4 Check Date Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 19,391$ 19,391$ 3% of other Division costs Demolition 1 LS 20,000$ 20,000$ Modifications to bioreactor 1 LS 250,000$ 250,000$ Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Coatings 1 LS 40,000$ 40,000$ Division 10 -Specialities Identification Devices 1 LS 1,500$ 1,500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 160,380$ 160,380$ 33% of Construction Cost Division 31 - Earthwork Excavation and backfill 1 LS 40,000$ 40,000$ Piping for Step Feed Operation 1 LS 45,000$ 45,000$ Step Feed Flow Meter 1 EA 10,000$ 10,000$ Step Feed Pump 1 LS 12,000$ 12,000$ Submersible Mixers 4 EA 20,000$ 80,000$ Subtotal 686,000$ Mobilization, Bonds, and Insurance 5%34,000$ Contractor's Overhead and Profit 10%69,000$ Subtotal 789,000$ Miscellaneous Items and Contingencies 25%197,000$ Total Estimated Construction Cost 986,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Divison 40 - Process Interconnections Estimate of Probable Construction Cost - Alternative SCT 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 23-Jan-19 Project No.10111714 Estimator R. Schultz Task Alternatives Eval Checked By C. Caprara Task No.4 Check Date Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 17,416$ 17,416$ 3% of other Division costs Demolition 1 LS 25,000$ 25,000$ Modifications to bioreactor 1 LS 25,000$ 25,000$ Misc Metal 1 LS 20,000$ 20,000$ Division 9 - Finishes Coatings 1 LS 15,000$ 15,000$ Division 10 -Specialities Identification Devices 1 LS 1,500$ 1,500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 144,045$ 144,045$ 33% of Construction Cost Division 31 - Earthwork Excavation and backfill 1 LS 20,000$ 20,000$ Misc. Piping 1 LS 25,000$ 25,000$ IFAS Equipment 1 LS 250,000$ 250,000$ Submerisble Mixers 4 EA 20,000$ 80,000$ Subtotal 623,000$ Mobilization, Bonds, and Insurance 5%31,000$ Contractor's Overhead and Profit 10%62,000$ Subtotal 716,000$ Miscellaneous Items and Contingencies 25%179,000$ Total Estimated Construction Cost 895,000$ Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 40 - Process Interconnections Estimate of Probable Construction Cost - Alternative SCT 4 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 23-Jan-19 Project No.10111714 Estimator R. Schultz Task Alternatives Eval Checked By C. Caprara Task No.4 Check Date Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 327,280$ 327,280$ 3% of other Division costs Demolition 1 LS 25,000$ 25,000$ Modifications to bioreactor 1 LS 250,000$ 250,000$ CMU Building for pumps and blowers 1 LS 300,000$ 300,000$ Misc. Metal 1 LS 75,000$ 75,000$ Division 7 - Thermal and Moisture Protection Thermal and Moisture Protection 1 LS 40,000$ 40,000$ Division 9 - Finishes Membrane Tank Coatings 1 LS 200,000$ 200,000$ Division 10 -Specialities Identification Devices 1 LS 2,500$ 2,500$ Division 22 - Plumbing Misc. Equipment Building Plumbing 1 LS 25,000$ 25,000$ Equipment Building HVAC 1 LS 35,000$ 35,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 2,706,825$ 2,706,825$ 33% of Construction Cost Division 31 - Earthwork Excavation and backfill 1 LS 75,000$ 75,000$ Misc. Piping 1 LS 200,000$ 200,000$ Membrane Equipment 1 LS 4,000,000$ 4,000,000$ Membranes, permeate pumps, backpulse pumps, chemical system, etc. Influent Fine Screens 4 EA 500,000$ 2,000,000$ RAS Screen 1 EA 400,000$ 400,000$ Membrane Scour Air Blowers 3 EA 200,000$ 600,000$ Subtotal 11,262,000$ Mobilization, Bonds, and Insurance 5%563,000$ Contractor's Overhead and Profit 10%1,126,000$ Subtotal 12,951,000$ Miscellaneous Items and Contingencies 25%3,238,000$ Total Estimated Construction Cost 16,189,000$ Divison 46 - Water and Wastewater Equipment Divison 4 - Masonry Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 40 - Process Interconnections Division 23 - Heating, Ventilating, and Air-Conditioning Estimate of Probable Construction Cost - Alternative SCL 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 8,490$ 8,490$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Misc Metal 1 LS 10,000$ 10,000$ Division 9 - Finishes Flat Cover Finish Work 3 EA 10,000$ 30,000$ Division 40 - Process Interconnections Misc. Mechanical 1 LS 5,000$ 5,000$ 76' Launder Cover 2000 SF 119$ 238,000$ NEFCO quote plus 40% installation costs Scaled up for 34" launder & 75' Clarfier Subtotal 301,000$ Mobilization, Bonds, and Insurance 5%15,000$ Contractor's Overhead and Profit 10%30,000$ Subtotal 346,000$ Miscellaneous Items and Contingencies 25%87,000$ Total Estimated Construction Cost 433,000$ Division 1 - General Requirements Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative SCL 3 Ph. 1 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 41,651$ 41,651$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Misc Metal 1 LS 10,000$ 10,000$ Division 9 - Finishes Flat Cover Finish Work 2 EA 45,000$ 90,000$ Option Kynar 500 paint system Division 26 - Electrical Electrical & Instrumentation work 1 LS 231,392$ 231,392$ 20% of Construction Cost. Update Elec. need to re-route conduit Division 40 - Process Interconnections Misc. Mechanical 1 LS 5,000$ 5,000$ 75' Flat Cover 8840 SF 119$ 1,051,960$ Average quote plus 40% installation costs (Billings & Wenatchee) Subtotal 1,440,000$ Mobilization, Bonds, and Insurance 5%72,000$ Contractor's Overhead and Profit 10%144,000$ Subtotal 1,656,000$ Miscellaneous Items and Contingencies 25%414,000$ Total Estimated Construction Cost 2,070,000$ Division 1 - General Requirements Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative SCL 3 Ph. 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 20,915$ 20,915$ 3% of other Division costs Demolition 1 LS 5,000$ 5,000$ Misc Metal 1 LS 5,000$ 5,000$ Division 9 - Finishes Flat Cover Finish Work 1 EA 45,000$ 45,000$ Option Kynar 500 paint system Division 26 - Electrical Electrical & Instrumentation work 1 LS 116,196$ 116,196$ 20% of Construction Cost. Update Elec. need to re-route conduit Division 40 - Process Interconnections Misc. Mechanical 1 LS 5,000$ 5,000$ 75' Flat Cover 4420 SF 119$ 525,980$ Average quote plus 40% installation costs (Billings & Wenatchee) Subtotal 723,000$ Mobilization, Bonds, and Insurance 5%36,000$ Contractor's Overhead and Profit 10%72,000$ Subtotal 831,000$ Miscellaneous Items and Contingencies 25%208,000$ Total Estimated Construction Cost 1,039,000$ Division 1 - General Requirements Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative SCL 4 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 49,095$ 49,095$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Misc Metal 1 LS 10,000$ 10,000$ Division 9 - Finishes Dome Cover Finish Work 2 EA 5,000$ 10,000$ AHU 2 EA 90,000$ 180,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 406,045$ 406,045$ 33% of Construction Cost. Update Elec. for humid corrosive environment Division 40 - Process Interconnections Misc. Mechanical 1 LS 5,000$ 5,000$ 76' Dome Cover 8840 SF 116$ 1,025,440$ CST (Billings) quote escalated, plus 40% installation costs Subtotal 1,696,000$ Mobilization, Bonds, and Insurance 5%85,000$ Contractor's Overhead and Profit 10%170,000$ Subtotal 1,951,000$ Miscellaneous Items and Contingencies 25%488,000$ Total Estimated Construction Cost 2,439,000$ Division 1 - General Requirements Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Division 23 - Heating, Ventilation and Air Conditioning Estimate of Probable Construction Cost - Alternative EFF 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 23-Jan-19 Project No.10111714 Estimator R. Schultz Task Alternatives Eval Checked By C. Caprara Task No.4 Check Date Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 363,988$ 363,988$ 3% of other Division costs Demolition 1 LS 25,000$ 25,000$ Equipment building, TMF Tankage, Pumping Station 1 LS 300,000$ 300,000$ CMU building for pumps and blowers 1 LS 300,000$ 300,000$ Misc. Metal 1 LS 75,000$ 75,000$ Division 7 - Thermal and Moisture Protection Thermal and Moisture Protection 1 LS 40,000$ 40,000$ Division 9 - Finishes Tank & Pumping Station Coatings 1 LS 300,000$ 300,000$ Division 10 -Specialities Identification Devices 1 LS 2,500$ 2,500$ Division 22 - Plumbing Misc. Equipment Building Plumbing 1 LS 25,000$ 25,000$ Division 23 - Heating, Ventilating, and Air-Conditioning Equipment Building HVAC 1 LS 35,000$ 35,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 3,010,425$ 3,010,425$ 33% of Construction Cost Division 31 - Earthwork Excavation and backfill 1 LS 200,000$ 200,000$ Misc. Piping 1 LS 400,000$ 400,000$ Membrane Equipment 1 LS 4,250,000$ 4,250,000$ Membranes, permeate pumps, backpulse pumps, chemical system, etc. Influent Fine Screens 4 EA 500,000$ 2,000,000$ RAS Screen 1 EA 400,000$ 400,000$ Membrane Scour Air Blowers 3 EA 200,000$ 600,000$ Secondary Effluent Pumps 3 EA 65,000$ 195,000$ Subtotal 12,522,000$ Mobilization, Bonds, and Insurance 5%626,000$ Contractor's Overhead and Profit 10%1,252,000$ Subtotal 14,400,000$ Miscellaneous Items and Contingencies 25%3,600,000$ Total Estimated Construction Cost 18,000,000$ Divison 46 - Water and Wastewater Equipment Division 1 - General Requirements Divison 3 - Concrete Divison 4 - Masonry Divison 5 - Metals Divison 40 - Process Interconnections Estimate of Probable Construction Cost - Alternative RAB 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 4,306$ 4,306$ 3% of other Division costs Demolition 1 LS 10,000$ 10,000$ Hydraulic Analysis 1 LS 15,000$ 15,000$ Letter of Map Revision 1 LS 8,000$ 8,000$ Wall Modificaiton 28 CY 450$ 12,600$ Approximate 35x45 (interior) x3 18" thick walls Floor Slab 60 CY 300$ 18,000$ Metal Building 1600 SF 35$ 56,000$ (Biosolids) estimate Aluminum Cover 200 SF 75$ 15,000$ (Kalispell) Jan 2007 estimate escalated Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Concrete Coating 1 LS 5,000$ 5,000$ Division 10 -Specialities Identification Devices 1 LS 500$ 500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 23,920$ 23,920$ 20% of Construction Cost Division 40 - Process Interconnections Misc. Mechanical 1 LS 5,000$ 5,000$ Subtotal 181,000$ Mobilization, Bonds, and Insurance 5%9,000$ Contractor's Overhead and Profit 10%18,000$ Subtotal 208,000$ Miscellaneous Items and Contingencies 25%52,000$ Total Estimated Construction Cost 260,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Estimate of Probable Construction Cost - Alternative RAB 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 23,461$ 23,461$ 3% of other Division costs Demolition 1 LS 25,000$ 25,000$ Reaeration Basin Tank 300 CY 300$ 90,000$ Approximate 35x45x10 18" thick walls Aluminum Railing 1 LS 5,000$ 5,000$ Aluminum Cover 1600 SF 75$ 120,000$ (Kalispell) Jan 2007 estimate escalated Misc Metal 1 LS 7,500$ 7,500$ Division 9 - Finishes Concrete Coating 1 LS 15,000$ 15,000$ Division 10 -Specialities Identification Devices 1 LS 500$ 500$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 194,040$ 194,040$ 33% of Construction Cost Excavation and Fill 1 LS 30,000$ 30,000$ Division 40 - Process Interconnections 3" Air Supply 800 LF 75$ 60,000$ 24" Final Effluent 800 LF 300$ 240,000$ Misc. Mechanical 1 LS 20,000$ 20,000$ Subtotal 831,000$ Mobilization, Bonds, and Insurance 5%42,000$ Contractor's Overhead and Profit 10%83,000$ Subtotal 956,000$ Miscellaneous Items and Contingencies 25%239,000$ Total Estimated Construction Cost 1,195,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 31 - Earthwork Estimate of Probable Construction Cost - Alternative AND 2 Kalispell AAWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 14,564$ 14,564$ 3% of other Division costs Demolition 1 LS 75,000$ 75,000$ Concrete Modifications 1 LS 25,000$ 25,000$ Misc. 1 LS 10,000$ 10,000$ Division 7 - Thermal and Moisture Protection Insulation 1 LS 5,000$ 5,000$ (CDA) escalated and rounded up Division 9 - Finishes Finishes 1 LS 15,000$ 15,000$ Division 10 -Specialities Identification Devices 1 LS 5,000$ 5,000$ HVAC Modification 1 LS 25,000$ 25,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 120,450$ 120,450$ 33% of Construction Cost Division 40 - Process Interconnections Piping 1 LS 20,000$ 20,000$ (CDA) escalated and rounded up Misc. Mechanical 1 LS 10,000$ 10,000$ Division 46 - Water and Wastewater Equipment Gas Equipment 1 LS 10,000$ 10,000$ (CDA) escalated and rounded up Recirculation Pumps 2 EA 70,000$ 140,000$ (Bozeman) phase 1 plus 40% install Heat Exchanger 2 EA 50,000$ 100,000$ (CDA) escalated and rounded up Subtotal 575,000$ Mobilization, Bonds, and Insurance 5%29,000$ Contractor's Overhead and Profit 10%58,000$ Subtotal 662,000$ Miscellaneous Items and Contingencies 25%166,000$ Total Estimated Construction Cost 828,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 23 - Heating, Ventilation and Air Conditioning Estimate of Probable Construction Cost - Alternative AND 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 78,005$ 78,005$ 3% of other Division costs Demolition 1 LS 100,000$ 100,000$ Cast In Place Concrete 1 LS 385,000$ 385,000$ (CDA) escalated and rounded up Concrete Reinforcing 1 LS 120,000$ 120,000$ (CDA) escalated and rounded up Steel Studs 1 LS 6,000$ 6,000$ (CDA) escalated and rounded up Metal Roofing 1 LS 20,000$ 20,000$ (CDA) escalated and rounded up Metal Siding 1 LS 36,000$ 36,000$ (CDA) escalated and rounded up Aluminum Ladders/Railings 1 LS 16,000$ 16,000$ (Kalispell) rehab Misc. 1 LS 6,000$ 6,000$ (Kalispell) rehab Structural and Misc. Steel 1 LS 40,000$ 40,000$ (CDA) escalated and rounded up Division 6 - Wood, Plastics, and Composites Joist and Deck 1 LS 19,000$ 19,000$ (CDA) escalated and rounded up Rough Carpentry 1 LS 5,000$ 5,000$ (CDA) escalated and rounded up Division 7 - Thermal and Moistur Protection Insulation 1 LS 5,000$ 5,000$ (CDA) escalated and rounded up Division 9 - Finishes Doors, Frames, Hardware, Louvers 1 LS 2,000$ 2,000$ (CDA) escalated and rounded up Roof Coating 1 LS 15,000$ 15,000$ (Kalispell) rehab Digester Coating 1 LS 150,000$ 150,000$ (Kalispell) rehab Painting 1 LS 50,000$ 50,000$ (CDA) escalated and rounded up Division 10 -Specialities Identification Devices 1 LS 5,000$ 5,000$ New HVAC 1 LS 35,000$ 35,000$ (CDA) escalated and rounded up Division 26 - Electrical Electrical & Instrumentation work 1 LS 645,150$ 645,150$ 33% of Construction Cost Excavation and Fill 1 LS 150,000$ 150,000$ (CDA) escalated and rounded up Division 40 - Process Interconnections Digester Piping 1 LS 100,000$ 100,000$ (CDA) escalated and rounded up Underslab Piping 1 LS 25,000$ 25,000$ (CDA) escalated and rounded up Yard Piping 1 LS 225,000$ 225,000$ Misc. Mechanical 1 LS 20,000$ 20,000$ Division 46 - Water and Wastewater Equipment Gas Equipment 1 LS 130,000$ 130,000$ (CDA) escalated and rounded up Mixer 1 LS 310,000$ 310,000$ (Kalispell) rehab plus 40% installation Foam Separator 1 LS 80,000$ 80,000$ (Kalispell) rehab plus 40% installation Subtotal 2,778,000$ Mobilization, Bonds, and Insurance 5%139,000$ Contractor's Overhead and Profit 10%278,000$ Subtotal 3,195,000$ Miscellaneous Items and Contingencies 25%799,000$ Total Estimated Construction Cost 3,994,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Division 31 - Earthwork Division 23 - Heating, Ventilation and Air Conditioning Estimate of Probable Construction Cost - Alternative STK 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 40,874$ 40,874$ 3% of other Division costs Demolition 1 LS 110,000$ 110,000$ Kalispell 2008 Dewatering demo. Escalated Concrete Work 1 LS 50,000$ 50,000$ Misc Metal 1 LS 20,000$ 20,000$ Division 9 - Finishes Finish Work 1 LS 20,000$ 20,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 350,460$ 350,460$ 33% of Construction Cost. Division 40 - Process Interconnections Process Piping 1 LS 25,000$ 25,000$ Connections 1 LS 10,000$ 10,000$ Rotary Lobe Pumps 3 EA 29,000.00$ 87,000$ (CDA) quote plus installation Pressurization Pumps 2 EA 25,000.00$ 50,000$ Dissolved Air Floatation Tank 2 EA 400,000$ 800,000$ Subtotal 1,563,000$ Mobilization, Bonds, and Insurance 5%78,000$ Contractor's Overhead and Profit 10%156,000$ Subtotal 1,797,000$ Miscellaneous Items and Contingencies 25%449,000$ Total Estimated Construction Cost 2,246,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative STK 4 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 51,846$ 51,846$ 3% of other Division costs Demolition 1 LS 110,000$ 110,000$ Concrete Work 1 LS 50,000$ 50,000$ Misc Metal 1 LS 10,000$ 10,000$ Division 9 - Finishes Finish Work 1 LS 20,000$ 20,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 441,210$ 441,210$ 33% of Construction Cost. Division 40 - Process Interconnections Process Piping 1 LS 45,000$ 45,000$ Rotary Lobe Pumps 3 EA 29,000$ 87,000$ (CDA) quote plus installation Disc Thickening System Equipment 3 EA 375,000$ 1,125,000$ Subtotal 1,940,000$ Mobilization, Bonds, and Insurance 5%97,000$ Contractor's Overhead and Profit 10%194,000$ Subtotal 2,231,000$ Miscellaneous Items and Contingencies 25%558,000$ Total Estimated Construction Cost 2,789,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative STK 5 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 21,722$ 21,722$ 3% of other Division costs Demolition 1 LS 110,000$ 110,000$ Concrete Work 1 LS 50,000$ 50,000$ Misc Metal 1 LS 30,000$ 30,000$ Division 9 - Finishes Finish Work 1 LS 20,000$ 20,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 192,060$ 192,060$ 33% of Construction Cost. Division 40 - Process Interconnections Process Piping 1 LS 45,000$ 45,000$ Rotary Lobe Pumps 3 EA 29,000$ 87,000$ (CDA) quote plus installation Rotary Screen Thickening System Equipment 2 EA 175,000$ 350,000$ (CDA) FKC Co. Ltd. quote plus 40% installation costs, RST, Floc. Tank, & Controls Subtotal 906,000$ Mobilization, Bonds, and Insurance 5%45,000$ Contractor's Overhead and Profit 10%91,000$ Subtotal 1,042,000$ Miscellaneous Items and Contingencies 25%261,000$ Total Estimated Construction Cost 1,303,000$ Division 1 - General Requirements Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Divison 3 - Concrete Estimate of Probable Construction Cost - Alternative STK 7 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Comments Unit Price Total Description Quantity Unit ($/unit) ($) General Conditions, Bidding, Submittals, Start-up 1 LS 30,101$ 30,101$ 3% of other Division costs Demolition 1 LS 110,000$ 110,000$ Concrete Work 1 LS 50,000$ 50,000$ Misc Metal 1 LS 10,000$ 10,000$ Division 9 - Finishes Finish Work 1 LS 20,000$ 20,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 261,360$ 261,360$ 33% of Construction Cost. Update Elec. for humid corrosive environment Division 40 - Process Interconnections Process Piping 1 LS 25,000$ 25,000$ Rotary Lobe Pumps 3 EA 29,000.00$ 87,000$ (CDA) quote plus installation Volute Thickener Equipment 2 EA 300,000$ 600,000$ Subtotal 1,193,000$ Mobilization, Bonds, and Insurance 5%60,000$ Contractor's Overhead and Profit 10%119,000$ Subtotal 1,372,000$ Miscellaneous Items and Contingencies 25%343,000$ Total Estimated Construction Cost 1,715,000$ Division 1 - General Requirements Divison 3 - Concrete Divison 5 - Metals Divison 46 - Water and Wastewater Equipment Estimate of Probable Construction Cost - Alternative BDD 2 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Unit Price Total Description Quantity Unit ($/unit) ($)Comments General Conditions, Bidding, Submittals, Start-up 1 LS 37,976$ 37,975.61$ Aerated Static Pile Excavation 2490 CY 10$ 24,278$ 16,800 sq feet x 4 feet deep Aerated Static Pile Bed (Asphalt)1867 SY 30$ 56,010$ 16,800 sq ft Curing Pile Excavation 1600 CY 10$ 15,600$ 10,800 sq ft x 4 feet deep Curing Pile Bed (Asphalt)1200 SY 30$ 36,000$ 10,800 sq ft Cured Compost Storage Excavation 963 CY 10$ 9,389$ 6,500 sq ft x 4 feet deep Cured Compost Storage Area Bed (Asphalt) 722 SY 30$ 21,667$ 6,500 sq ft New Bulking Agent Storage Excavation 515 CY 10$ 5,021$ 3,480 sq ft x 4 feet deep New Bulking Agent Storage Area Bed (Asphalt) 390 SY 30$ 11,700$ 3,480 sq ft Recycled Bulking Agent Storage Excavation 450 CY 10$ 4,388$ 3,025 sq ft x 4 feet deep Recycled Bulking Agent Storage Area Bed (Asphalt) 340 SY 30$ 10,200$ 3,025 sq ft Biosolids Storage Excavation 33 CY 10$ 330$ 225 sq ft x 4 feet deep Biosolids Storage Area Bed (Asphalt)25 SY 30$ 750$ 225 sq ft Stormwater Detention Pond Excavation 2370 CY 10$ 23,108$ 16,000 sq feet x 4 feet deep Roadways 6000 SY 30$ 180,000$ Average area between the three layouts Fencing 2640 LF 27$ 71,280$ 10 acres ASP Enclosed Building 19000 SF 35$ 665,000$ Biosolids Storage Enclosed Building 750 SF 35$ 26,250$ Cure Pile Open Air Building 11000 SF 25$ 275,000$ Hamilton bid tab Office Building 1600 SF 55$ 88,000$ Biofilter Construction 1 LS 125,000$ 125,000$ Cemetary Road Water Main Extention 2600 LF 120$ 312,000$ Includes Surface Restorationa and Appurtenant Items Septic tank and drain field 1 LS 15,000$ 15,000$ Cemetary Road Improvements 2600 LF 59$ 153,400$ Curb/Gutter, sidewalk, boulevard, sod, sprinklers Cemetary Road Stormwater 2600 LF 75$ 195,000$ Pipe, inlets and manholes. No surface restoration Aerated Static Pile Concrete Footing and Walls 400 CY 500$ 200,200$ 9 100' Long Walls, 9 10' Long Walls, Wall Height 6 feet, Wall Thickness 8 inches, Footing Width 3 feet, Footing Thickness 1 foot Curing Pile Concrete Footing and Walls 262 CY 750$ 196,560$ 4 100' Long Walls, 4 12' Long Walls, Wall Height 6 feet, Wall Thickness 8 inches, Footing Width 3 feet, Footing Thickness 1 foot Cured Compost Storage Area Concrete Footing and Walls 62 CY 750$ 46,800$ 6,500 sq ft. Assumed 100 x 32 ft beds. Same assumptions as above New Bulking Agent Storage Area 75 CY 750$ 56,250$ 2,250 sq ft. Assumed 100 x 22 ft beds. Same assumptions as above Recycled Bulking Agent Storage Area 75 CY 750$ 56,250$ 1,950 sq ft Assumed 100 x 20 ft beds. Same assumptions as above Sealants and Caulking 1 LS 5,000$ 5,000$ Division 9 - Finishes Painting 1 LS 10,000$ 10,000$ Division 11 - Equipment ASP Blowers 14 LS 4,600$ 64,400$ New York Blower 2012A Biofilter Blower 2 LS 3,200$ 6,400$ New York Blower 1708A Screen 1 LS 175,000$ 175,000$ McLanahan TT517 Mixer 1 LS 228,332$ 228,332$ Roto-Mix, 40' Conveyor, Control Panel, and Freight (Missoula Compost) Hopper/Conveyor 2 LS 16,000$ 32,000$ Vulcan 12' Incline Feed Conveyor Woodchipper 1 LS 10,000$ 10,000$ Division 15 - Mechanical Under Drain Piping 250 LF 60$ 15,000$ Assume that most of the original estimate goes in with Phase 1 Main Trunk Piping 450 LF 180$ 81,000$ Assume that most of the original estimate goes in with Phase 1 ASP and Biofilter Air Piping 1 LS 75,000$ 75,000$ Manhole 2 EA 5,000$ 10,000$ Assume that most of the original estimate goes in with Phase 1 Valves 1 LS 15,000$ 15,000$ Assume that most of the original estimate goes in with Phase 1 Division 16 - Electrical Electrical Service to Site - Flathead Electric Work 1 LS 65,000$ 65,000$ Electrical/I&C 1 LS 125,000$ 125,000$ Estimated Subtotal 3,836,000$ Mobilization, Bonds, and Insurance 5%192,000$ Subtotal 4,028,000$ Montana Tax 1%40,000$ Subtotal 4,068,000$ Miscellaneous Items and Contingencies 25%1,017,000$ Subtotal 5,085,000$ Inflaction Factor (mid-2019)1.03$ Subtotal 5,238,000$ Heavy Equipment (Skid Steer @ $75k and Backhoe @ $125k)200,000$ Total Estimated Construction Cost 5,438,000$ Division 1 - Special Conditions Division 2 - Site Work Division 3 - Concrete Division 7 - Thermal and Moisture Protection Estimate of Probable Construction Cost - Alternative BDD 3 Kalispell AWWTP - Facility Plan Update 2018 Project Kalispell Facility Plan Update Date 28-Dec-18 Project No.10111714 Estimator A. Nord Task Alternatives Eval Checked By R. Schultz Task No.4 Check Date 17-Jan-19 Unit Price Total Description Quantity Unit ($/unit) ($)Comments General Conditions, Bidding, Submittals, Start-up 1 LS 25,354$ 25,354$ 3% of other Division costs Demolition 1 LS 100,000$ 100,000$ Concrete Footing and Walls 75 CY 500$ 37,500$ Metal Storage Building 1 LS 75,000$ 75,000$ Sealants and Caulking 1 LS 5,000$ 5,000$ Division 9 - Finishes Painting 1 LS 15,000$ 15,000$ Division 26 - Electrical Electrical & Instrumentation work 1 LS 712,635$ 712,635$ 33% of Construction Cost Excavation 1 LS 35,000$ 35,000$ Asphalt 1 LS 30,000$ 30,000$ Misc. Piping 1 LS 45,000$ 45,000$ Valves 1 LS 25,000$ 25,000$ FKC SHX 800 x 6500L Class A Screw Press 2 EA 850,000$ 1,700,000$ FKC quote + 40% installation Boiler 1 EA 182,000$ 182,000$ Lime System 1 LS 75,000$ 75,000$ Subtotal 3,062,000$ Mobilization, Bonds, and Insurance 5%153,000$ Contractor's Overhead and Profit 10%306,000$ Subtotal 3,521,000$ Miscellaneous Items and Contingencies 25%880,000$ Total Estimated Construction Cost 4,401,000$ Division 1 - Special Conditions Division 3 - Concrete Division 7 - Thermal and Moisture Protection Divison 46 - Water and Wastewater Equipment Divison 40 - Process Interconnections Divison 31 - Earthwork Division 5 - Metals Divison 32 - Exterior Improvements APPENDIX C SITE PLAN FIGURE 700 SW Higgins, Suite 200 Missoula, MT 59803406.532.2200 hdrinc.com We practice increased use of sustainable materials and reduction of material use. © 2019 HDR, Inc., all rights reserved.