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1. WWTP Odor Control.. . . . . . . . . . . . . . . -'r 7- "hubl'c Work,-, Doapnrtmi::%nt &a ispe C tj nl" 11 %V-� a %11� Post Office Box 1-997, Kalispell, Montana 3 - Telephone (0 - r 2 , Fax(406)758-7831 REPORT -9 Mayor and City Council FROM: J'ames C. HanHansz, P.E., Director of Public Wo SUBJECT.* Wastewater Plant Odor Control Study — C MEETING DATE: 3 October 2005 The expansion of the Kalispell wastewater treatment plant includes a significant effort to better .manage odors produced as part of the treatment process. The design team of Mornslon-Maiel HDR Engineers has performed a comprehensive facility -wide study of the various odor sources and will. make a presentation of them- findings. The study is included as Technical Memorandum # 13 in the detailed Basis of Design Report that is being compiled for the expansion project. Attached. is a copy of the Executive Summary extracted from the 5 o page Technical Memorandum 4, 13. The foal Technical Memorandum is available for your review upon request. tob r , 2.005 WWTP Odor Control Presentation.doc MIMORMSON City of Kalispell Public'Works pan ent 00 , Technical Memorandum No,, 13 FACILITY WIDE ODOR CONTROL City of Kalispell Advanced Wastewater Treatment Plant Phase 1 Expansion PREPARED Y: Mark Smith HDR - Craig Cap r ra , P.E. - HDR REVIEWED Y: Dan Harmon, P,E} - H R DATE: September 28, 2005 13,1 EXECUTIVE SUMMARY The City of Kalispell is currently planning improvements to the Kalispell AWWTP as recommended by the Kalispell Wastewater Facility Plan, March 2004. These improvements are referred to as the Ph . e 1 Expansion. Residential and commercial development has encroached on the once remote wastewater treatment facility over the gears bringing odor emission from the facility to the forefront of concern* While the focus f the Phase 1 Expansion Project is to increase the hydraulic and treatment capacity of the facility, controlling odor emissions from the facility has increased in priority since the completion of the Kalispell Wastewater Facility Plan in March of 2004. The purpose of this Technical Memorandum is tot • Identify and evaluate odor generation at the AWVVTP. • Develop a plan for containment and treatment of each source of odor. • Provide estimates of probable cost for containing, ventilating, and treating each source of odor. • Quantify the benefit of treating each odor source. Recommend an approach to eliminating foul air emission from the AWWTP through a prioritized plan. Technical Memorandum No. 13 3- Kalispell DTP Phase I Expansion 13-1.1 Background The Kalispell Advanced Wastewater Treatment Plant AWVv P is located along Ashley Creek adjacent to the Kalispell Airport, The AWW1"P has been located on this site since 1942. Significant expansions occurred in 1959, 1973, and 1992. Figure 13-1 provides a treatment plant vicinity map and Figure 1 3-3 is a site plan of the existing ASP. The Kalispell AWVVTP provides advanced treatment to wastewater flow from the City of Kalispell and the Evergreen Water and Sewer District. Processes include screening and grit removal l eadworks , influent pumping, primary clarification, flow equalization, biological treatment ioreactors , secondary clarification, ultra violet light disinfection, re -aeration, gravity thickening/fermentation, anaerobic digestion, and solids handling (DAF Thickening, Belt Filter Press Dewaterir g, solids Loading). Flow from the Evergreen system contains a significant contribution from septic tare effluent pumping (STEP) systems and is conveyed through a long forcemain to the AWWTP. There are concerns that Evergreen effluent is a significant contributor to foul air release at the eadwors. The existing odor control system was constructed in 1992 as part of the Biological nutrient removal expansion project. It was designed to treat foul air from the Headworks, Solids Handling, and Gravity Thicken r e.rmrrter process areas. These areas are currently contained and ventilated to are r Scrubber focated adjacent to the solids handling room. The existing treatment system. was never effective at treating odor; it posed safety problems with regard to the pica[hand ling, and had a high O&M cost. Subsequently the chemical treatment portions of the' scrubber were removed and the unit is used solely to disperse foul air to the atmosphere:. Odorous substances that are emitted from domestic wastewater collection and treatment processes include .both inorganic gases, such as hydrogen sulfide H S and ammonia, and organic gases and vapors. Although H2S is considered to be the most prevalent odorous compound in wastewater, it should not be presumed that an odor problem is.excl.u.sively caused by H2S. Gas and liquid phase testing was conducted at the WWTP- ' ss st in characterization and quantification of odor sources. Foul air Sample's' were take6 and analyzed by dynamic dilution olfactormetry using a trained and scre'e. d odor panel, and were quantified in terms of dilution -to -threshold ratio and Odor+intensity in accordance with ASTM Methods E-6 -91 and �-5 . The D/T values r present the number of dilutions that would allow 50of the population to detect and'fec.ognize the 0 rticular odor. Essentially, the higher the D T value, the higher the odor: concentration. Conversely, the lower the DIT value, the lower the odor co n cer tration. I nten.sity. is the relative strength of the odor above the recognition threshold. The r -1 dtahol scale is used for purposes of referencing odor intensity in documentation entatior and communication. A larger value of n-butar of equates to a stronger odor. Conversely, a smaller value of r -l. utar of equates to a weaker odor. Table 13.1 summarizes the results of this testing. Technical Memorandum No. 13 3-2 Kalispell , WWTP Phase I Expansion EXISTING TREAT IV NT PLANT VIOL ITK' MAP EXISTING TREATMENT PLANT SITE PLAN Table 3- - e orted Odor Panel Data Process/Locafionorted IT I ntensit Existing Scrubber Stack J 206 n ravity Thickener 56 Primp Clarifier 2600 85 Seconds i ester 20 10 Solids Loading Room 160 1 2 Aerated irector 68 H edrorks,�cree n i n oom Solids Handling Room 190 75 Compost Facility--310 85 jrnpery Pond 65 12 estimated value Equivalent ppm of 1-butanol Hydrogen sulfide concentrations were also sampled at various locations at the A 1 1vRTP, in the sewer collection system, and at the Evergreen Pumping Station. Table 3-2 summarizes the results of the hydrogen sulfide testing. Table 3-2 - Results of H S Grab SaT � Location EH2s pm Gravity � Thickener 1 Digestion 0.06 Influent Box 38 redworks �Headworks Screenin IRoom �54 fl Influent ..�� met �e�� 1.5 LPrim Clarifier 1 �8 Equalization Basin 022 Downwind of Scrubber Exhaust 0.11 Eveyee Mbo e 46 City Shop Manhole . . ...... ............. . . .............. -- 0.2. Liquid phase testing was conducted by plant personnel by taking grab samples using G stec 211 LL dissolved sulfide ion tubes at various locations at the AWWTP and at the Evergreen Pumping Station. Table 18-8 summarizes the results of the liquid phase testi n . Technical Memorandum No. 13 18-5 Kalispell AVVWTP Phase I Expansion Table 3,-3 - Results of Dissolved Sulfide Grab Sam ling Locafion Date ime [S Manhole 26/05 1: # ■//JYo rre PM green Manhole 29 o5 :35 &5 M dworks Influent 2 o� . 5 o. Box Primary Clarifier 26� 1:5V .o PM Evergreen Lift Station : 5 i 9 -� 2 90 0.5 Tests showed that hydrogen sulfide and dissolved -'S� fide were significantly high at the H adv orks and Evergreen manhole. The AWVVTP is surrounded by residential drnont to. the vest and commercial development to the east. Historical records of odcomplaints concerning the ASP are very limited. To gain an understanding of h ist ric01:odor complaints, operating staff were interviewed and neighboring businesses and r s'idents were invited to a workshop that included discussion on odor sources and a tour of the.AVVVV" . The following in information was obtained: Odor complaints have occurred sporadically over the years* 0 When winds. a6 'sling from the east, odors are noticed in the residential neighborhoods to t : W.est of the ASP, 0 One neighbor recognized the odor from the Primary Clarifiers as noticeable at her residence when winds are out of the east. 13.1.2 Identification and.Ranking of Odor Sources Odor sources at the Ate. were ranked with regard to intensity, volume, frequency of occurrence, and other impact such as corrosion or operator safety. Table 3 summarizes the overall rank for 'eachprocess evaluated. Technical Memorandum No. 13 13-6 Kalispell Av WTP Phase N Expansion Table 134 - Summary of Odor Source Overall Ranking r Source Overall Rank"_ r rks Sor i Room t umia r Clarifier Eaualization M iorator L Secondary Clarification Re -Aeration Fermentation Anaerobic is i estion DAF Thickening M Dewatering l Solids Loading H UVfdldlf rvd11&1HY of UUUF Oour L -. JOWUr priority, IVI - r irat priority, H - higher priority) 3.1.3 Available Control Alternatives Odor is sometimes referred to as the " second fflu nt"' from wastewater treatment plants. Historically odor control has been approached in the..same manner once applied to sewage effluents -- separation by large buffer zones t o� w mixing with the ambient environment and dilution. of th.e odor before someone off -site was exposed to it. This is the current method employed at. the Kalispell AWWT P. With commercial and residential development olosin.g'.: i on the ASP, this has become impractical. Alternatives to controlling foul . r...'emiss.i. ns from the Kalispell AWWTP include prevention.,. o ain t en i for re' Ate rat, dispersion, odor modification, and mitigation'; Alte''Ma'.t.ive treattnent options wer'e developed and evaluated in the 2004 Waste 't� r oiiiti ':. Plan. They included chemical oxidation towers, activated carbon adsor ion, compost . fi t r soil fi Ite r o on tion and thermal oxidation. They were valu' based on capita.1. and operating expenses. Other factors, such as the treatment -plant location and size were also taken into consideration The following list details the specific cnteria-�e aluat d for each process. 1. Pot nti l' 5u s rbti lly Reduce Off -Site Odors • Magnitu'.of odor source mitigated • Effectiveness of odor control measure 2. Improves Worker Safety Eliminates hazardous con ib n • improves unacceptable indoor air quality • Upgrades ventilation rates to applicable codes 1 Provides Multiple Benefits Improves process control Reduces corrosion of equipment and structures Technical Memorandum No. 13 3- Klill AVVWrP Phase I Expansion • improves relations with neighbors (other than by reducing odors) . Technically Sound • Proven technology • Reliability • O&M requirements 5. Compatible with Future • Compatible with future expansions and process changes • Expandable • Does not involve extensive cost for facilities likely to be replaced soon 6, Implementation • Can be implemented quickly . Cost • Capital • Operating • Cost-effective for benefit achieved The 2004 Wastewater Facility Plan recommended that odors be contained and ventilated to compost bed filter treatment. 13.1.4 Recommended Plan Alternatives were evaluated and a te'commended approach developed for each unit process at the Kalispell AWWT . The. rec O.'Mmended plan is comprised of a wide range of elements to eliminate off -site odor emissions., improve worker safety, protect facilities from corrosion, and improve process o trol. The recommended plan was developed to: • Evaluate elimination of adverse imots'.' r neighbors of the facilities; • Evaluate the cost of odor control for each -'Unit process; • Evaluate the cost versus benefit of controlling odor for each unit process; • Provide a.priontized plan for odor control based on the ranking of odors; • Provide. cost 0ective solutions; • Provide' flexibility. to accommodate future expansions or process changes; and Ma' imize multiple benefits such as enhanced worker safety or equipment protection w ire.. they can be economically attained. Specific redo''mmendations.were developed for containing, ventilating and treating foul air for each u ft -.proc ss including: • Howrks : • Influent m— in • Primary Clarification Is Flog Equalization • Bioreactors • Secondary Clarification • Re -Aeration • Fermentation • Anaerobic Digestion • DAF Thickening • Dewatering 'nil Memorandum No. 13 13-8 Kalispell AWWTP Phase I Expansion Solids Loading The capital cost of containing, ventilating, and treating foul air for each of these unit processes in the Phase 1 Expansion project, and for future facilities was evaluated. Table 13- 5 summarizes these estimated capital costs. Figure 13-8 depicts the layout of odor control facilities if each of these unit processes is provided odor control. Table 1X5 - Unit Process Odor Control Capital Cost Summary Unit Process Phase 1 c "e- Future Facilities c s ,#4 Headworks $126,900 Influent Pumpi.ng $55500 $3700 Prima c r ifica ion $270700 $1 012,500 Equalization $367,500 Bioreactors $21550155 � c n a car i�a ion $1,1 9,15 $374�050 Ike- t a on $70,000 Fermentation $145800 $21,400 Anaerobic Digestion $22,100 $6,200 DAF TWIckening $337100 � Sands loading ( $132,900 _ j - � All costs are in raid 2005 dollars and should be escalated to the mid -point of construction for budgeting purposes_ Costs include allowances for construction contingency., which accounts for unknown bidding climates, Breather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. Allowances for engineering, legal and administration are not included. Technical Memorandum No. 13 3-9 Kalispell AWWTP Phase I Expansion The operations and maintenance cost of ventilating and treating foul air for each of the process units was also evaluated on a 20-year present worth basis. Table 1 3-6 summarizes these estimated O&M costs, Table 3- - Unit Process Odor Control O&M Cost Summary Unit Process Phase I Cost Future Facilities Cost Headworks $126,700 Influent Pumping $391000 - Primary Clarification $21)900 $115,000 $21,900 .Equalization Blore otors $726,300 son Clarification $299,850 $99,950 Re -Aeration $7,800 rm nt ti n $24,400 $24�400 Anaerobic Digestion $51900 $25000 DAF Thickening $19,500 - Dewatering, $2511500 Solids Lair $125,000 0.1 ear Present Worth calculated with an interest rate of % Based on the estimated capital cost, O&M cost, and ranking of odor sources at the AWVVTP, a cost versus benefit analysis was completed. Table 13-7 summarizes this analysis. Table 3- - CostlBeneffl Ranking Summary Unit Process Benefit cost Costs Benefit Priority Ranking eadwor s H M M/H Influent Pm L Ll Prima Clarification M H HM t alization M H H/M 9 ioreators L H HL 11 Secondary Clarification ......... ..... H L 12 Re -Aeration L L LPL 10 Fermentation H M MH 3 Anaerobic Digestion L H D F Thickening M L UM Dewaterin H H/H solids Loadin H M M/H 5 This value is the relative benefit of treating foul air from the subject unit process L= cost less than $100,000, M= cost between $1007000 and $200,000, H= cost greater than $too}oo . Containment, ventilation and treatment of all unit processes at the Kalispell AWVVTP i the Phase 1 Expansion project would be a significant cost and could monetarily limit the ability of the City to construct the necessary process improvements is to provide service and meet NPD S discharge permit requirements. It is recommended that the Phase 1 Technical Memorandum No. 13 13-11 Kalispell AWWTP Phase I Expansion Expansion Project include odor control of the unit processes that will provide the greatest benefit to reducing foul air emissions from the ASP. These processes include the Headworks, Influent Pumping, Fermentation, Anaerobic Digestion} DAF Thickening, Dewatering and solids Loading. Table 13-8 summarizes the capital cost for odor control of these unit processes. Table 3-- Recommended Phase I Odor Control Capital Cost Summary Unit Process Phase l Cost wrs $126,900 dV nfluent Pumping $551500 Fermentation $145800 Anaerobic DI ti n $227100 DAF Thickening$331100 w r y $352}800 S olds L d $132�900 Total Cap'ItaCost $869,100 All costs are in raid 2005 dollars and should be escalated to the mid -point of construction for budgeting purposes. 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. Allowances for engineering, legal and administration are not Included. It is recommended that treatment processes that will provide a medium level of benefit from treatment be given a secondary priority. These processes should be treated in future phases of expansion if off site odors persist after construction of Phase 1 improvements are c6 mpl t . Phase 1 improvements should include the flexibility to incorporate these processes in the future if necessary. These processes include Flow Equalization and Primary Clarification. Table 3-9 summarizes the capital cost for treating these unit processes. Figure 3-9 depicts the layout of the recommended odor control facilities. Table 3- - Secondary Priority Odor Control Capital Cost Summary Unit Process Phase I CoSl,2 Prima!y_Clariification $270,700 Eql tion $367,500 Total Capital Cost$638,200 Ji II mil- /`4Y'SI'tl" ��ii Ais #-1 ]-. �i_.L_ -t i_ t1 :�1 ------------------- ----------- 1_X11 coot cite in Mid Technical Memorandum No. 13 13-1 Kalispell AVVVVTP Phase I Expansion 4 p G E R ......., •,r.'`, S�ATi(;M Yii lWE�L. EkRA5i514N `.. .......... '.. Q................................................... :... �_� `. .... RD.K. I , --•- ,. ..F.h7k19i�t55 i -- ...... ....... . .... . ........................ ...-........-.........�... ...... .. ....................... .......s.::,.,.:..u; .. ,�...<.... _ - ME .. , PROPOSED PHASE 1 ODOR CONTROL SITE PLAN Treatment of secondary and tertiary unit processes is not recommended. The cost for containment, ventilation and treatment of foul air from these unit processes is high and little noticeable benefit to off site odor emission can be expected. These unit processes include Bioreactors, Secondary Clarification, and Re -aeration. Table 13-10 summarizes the capital cost for treating these unit processes. Table 3- - Secondary and Tertiary odor Control Capital Cost Summary Unit Process Phase Cosh Bi reactors $2,5501155 Secondaq Clarification $11149,150 Re -aeration $70,000 Total Capital Cost $3,769,305 Il c . o . sts are in mid 2005ar and s I d be escalated to the mid -point of construction for budgeting purposes. Costs include allowances for construction contingency, which accounts for unknown bidding climates, Breather delays, and labor and supplier delays. This allowance also accounts for many unanticipated site factors. Allowances for engineering, legal and administration are not included. 13.1.5 Additional Recommendations it is recommended that pilot testing be performed on the Evergreen system to determine the best approach for controlling the formation of :sulfides and the subsequent release of hydrogen sulfide at the Kalispell ASP. Processes tested should include chemical injection, and utilization of the existing aeration system at the Evergreen Lift Station. Prior to proceeding with final design of the recommended odor control system, additional sampling and testing should be performed. Testing should include: • Continuous H2Smonitoring at the Feadror • /T and odor intensity testing on the existing scrubber stack • Ammonia concentration at the Fermenter, Secondary Digester and Solids Handling processes • Gas chromatography analysis for sulfur compounds from select processes. Technical Memorandum m No. 13 13-14 Kalispell AVVVVTP Phase I Expansion