Watertown Wastewater Facility Plan. August 11, 2015

Transcription

1 Watertown Wastewater Facility Plan August 11, 2015

2 Watertown Wastewater Wastewater Treatment Facility History Comprehensive Planning Wastewater Concerns Capacity Condition Permitting Requirements

3 Watertown WWTF Extended aeration activated sludge facility constructed in 1992 with a design population of 4,026and an average wet weather flow of 1.26 MGD.

4 Watertown WWTF 1992 Design Pollutants Carbonaceous Biochemical Oxygen Demand (CBOD 5 ) Total Suspended Solids Ammonia Nitrogen E. coli (harmful bacteria)

5 Watertown WWTF Unit Treatment Processes Influent Lift Station Flow Equalization Screening Aeration Clarification Sand Filtration Chlorination Post Aeration Anaerobic Digestion

6 Watertown WWTF

7 Watertown WWTF

8 Watertown WWTF Final Clarifiers Aeration Basins Digester Sludge Storage Filters Chlorine Contact

9 Watertown WWTF Current NPDES Effluent Limits (expired Sept. 2014) CBOD 5 5 mg/l TSS 30 mg/l Ammonia mg/l Chlorine mg/l

10 Watertown WWTF 2006 Wastewater Treatment Facility Plan Planning Population 7,700-9,000 Recommendations Grit removal Aeration and clarification Filtration Biosolids Bio-P and ChemP Lab/Office Space

11 Watertown WWTF 2013 Preliminary Wastewater Treatment Facility Evaluation Maximum theoretical treatment capacity for a population of 4800 residents. Rehabilitiation/replacement Future effluent limits Implementation schedule for 2016 or 2017 (IUP)

12 Watertown WWTF 2015 Wastewater Treatment Facility Plan Planning Population 7,000 Recommendations Screening and grit removal Aeration and clarification Filtration Biosolids Bio-P and ChemP Lab/Office Space SCADA

13 Watertown Wastewater Wastewater Treatment Facility Planning Capacity Condition Permitting Requirements

14 Watertown WWTF Capacity 7,000 Watertown Population 6,000 5,000 4,000 3,000 2,000 1, Historical Population Projected Population WWTF Design Population Max Thoeretical Population

15 Watertown WWTF Capacity Influent Flow (MGD) Average Annual Influent Flow (MGD) 30-day Wet Weather Flow (MGD) Design Average Dry Weather Flow (MGD)

16 Watertown WWTF Capacity Influent CBOD 5 (lb/day) 1, Average Influent CBOD (lb/day) Peak Month Influent COBD (lb/day) Design Average Influent CBOD (lb/day)

17 Watertown WWTF Capacity 2,500 Influent TSS (lb/day) 2,000 1,500 1, Average Influent TSS (lb/day) Peak Month Influent TSS (lb/day) Design Average Influent TSS (lb/day)

18 Watertown WWTF Capacity 160 Influent Phosphorus (lb/day) Average Influent Phosphorus (lb/day) Peak Month Influent Phopshorus (lb/day)

19 Watertown WWTF Capacity Influent Design Criteria Average Dry Weather Flow Design Average Flow Average Wet Weather Flow Peak Hourly Flow Peak Instantaneous Flow 0.60 MGD 0.80 MGD 1.26 MGD 2.15 MGD 2.36 MGD Carbonaceous Biochemical OxygenDemand (CBOD 5 ) 1,400 lb/day Total Suspended Solids (TSS) 1,600 lb/day Total Kjeldahl Nitrogen (TKN) 350 lb/day Total Phosphorus(P) 70 lb/day Influent design loads based on normal domestic per capita loading rates.

20 Watertown WWTF Capacity Capacity Needs for Design Flow and Load (with current effluent limits) OK for projected flow Improvements needed for projected load Aeration Biosolids

21 Watertown Wastewater Wastewater Treatment Facility Planning Capacity Condition Permitting Requirements

22 Watertown WWTF Condition Rehabilitation / Replacement Facility equipment exceeds typical 20-yeardesign service life. Aeration membrane recommended life of only 5-10 years. Minimal service due to anticipated growth period following 2006 Facility Planning Process Major rehabilitation/replacement work required

23 Watertown WWTF Condition Screening

24 Watertown WWTF Condition Aeration

25 Watertown WWTF Condition Clarification

26 Watertown WWTF Condition Filtration

27 Watertown WWTF Condition Disinfection

28 Watertown WWTF Condition Biosolids

29 Watertown WWTF Condition Lab/Office Electrical Service MCC/SCADA Boilers/Heat

30 Watertown WWTF Condition Condition Concerns/Operational Challenges Screening and grit removal Aeration / diffuser replacement Clarifier mechanisms and sludge pumping Filter media and mechanisms Digester and sludge storage

31 Watertown WWTF Permitting Permit Expired September 2014 Waiting for Effluent Limits Determination and Draft Permit

32 Watertown WWTF Permitting Permitting Issues and Concerns Phosphorus 0.15 to 1.0 mg/l based on river eutrophication standards Total Nitrogen Forcasted in the next 10 years at approximately 10 mg/l Chloride (and other salty discharge parameters) Forcasted at 230 mg/l or less (compliance schedule) Mercury Limit of 6.9 ng/l or less if July 2014 sample not omitted from RP analysis due to high flow conditions. Others: copper, silver, selenium, chromium, DEPH

33 Watertown WWTF Permitting Nutrient Removal (phosphorus and nitrogen) Biological P and N Removal Carbon:nitrogen:phosphorus ratios Recirculation with anoxic / aerobic Lower sludge production Interaction with solids processing (phosphorus release) Chemical P Removal Precipitation with ferric chloride or alum Increased sludge production Required for polishing even with bio-p

34 Watertown WWTF Permitting Chloride Source removal is most feasible alternative Mercury Source reduction Filtration Deep Bed Media Membranes

35 Watertown WWTF Planning Facility Planning Questions Are the current treatment processes adequate for proposed effluent limits? No, additional treatment processes are necessary to meet proposed phosphorus limits. Mercury should be closely monitored and chloride will be addressed in the next permit cycle. Are phosphorus removal improvements required prior to a proposed facility expansion? Based on current projections, additional capacity will be required before the projected 2020 compliance date for phosphorus removal.

36 Watertown WWTF Planning Is expansion or replacement of the current unit treatment processes most cost effective? This varies by unit process. Aeration can be expanded, however, preliminary treatment and filtration are best to be replaced. What components would be reused and can be rehabilitated or replaced prior to a major facility project? Items that may be addressed prior to a major facility project include diffuser replacement/expansion, sludge pumping, and clarifier drives. What are the anticipated capital and O&M expenditures associated with the recommended improvements? Major O&M expenditures are related to electricity and chemical costs. Annual cost for ferric chloride is estimated at $50,000. Biosolids disposal costs are currently accumulating. Other?????

37 Watertown WWTF Improvements Recommended Improvements Condition Capacity Compliance Replace Membrane Aeration System X X X Replace Secondary Clarifier Mechanisms X Biosolids Treatment and Storage Convert anaerobic digester to aerated storage tank X X Provide dedicated aeration blower for sludge stabilization X X Construct liquid biosolids storage and loadout facilities X X RAS/WAS Pumping and Piping Improvements X Replace Effluent Filtration (deep bed media or membrane) X X Chemical Feed to Final Clarifiers for Chemical Phosphorus Removal X Biological Phosphorus (and Nitrogen) Removal

38 Watertown WWTF Improvements Recommended Improvements Condition Capacity Compliance Construct anaerobic and anoxic basins and mixers X Construct mixed liquor and nitrified recycle systems X Aeration Blower Replacement / Upgrade X X Replace/Upgrade Preliminary Treatment Screening Grit Removal Lab/Office Supervisory Control and Data Acquisition System (SCADA) Disinfection X X X X X Salty Discharge Parameter Compliance (non-wwtf improvement) X

39 Watertown WWTF Improvements What can we do today to address WWTF condition concerns? Replace/expand existing fine bubble diffusers Convert anaerobic digester to aerated storage Demo heat exchanger, gas collection and mixing Replace clarifier mechanisms Replace RAS/WAS pumps and valves Project staging Filtration before preliminary treatment/disinfection/office Digestion conversion before RAS/WAS pump replacement

40 Watertown WWTF Planning Update 20-year Population Projections Submit Effluent Limits Request to MPCA Submit Wastewater Facility Plan to MPCA March Public Hearing and Resolution NPDES/SDS Permit Reissuance with new limits?? 2015 Request Placement on 2017 Project Priority List June 2016 Phase 2+ Project Listed on 2017 Intended Use Plan Oct Submit Phase 2+ Plans and Specifications to MPCA Jan Initiate Construction of Phase 2 July 2017 Complete Construction of Final Phase July 2019 Final Date of Compliance (with new limits)?? 2020 (est)

41 Watertown Wastewater Questions and Comments Lana Tullis, P.E. Andrew Budde, P.E. Bolton & Menk, Inc. Bolton & Menk, Inc. Ph: (952) Ph: (952) Mo: (612) Mo: (612)

42 Watertown WWTF Discussion