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ITEM 1 Wastewater Master plan progress summaryOtsego Wastewater Master Plan City Council Update – March 27, 2017 Otsego Wastewater Master Plan Progress Summary I.Meetings with City a. Kick-Off b. Public Works Subcommittee c. Utilities Staff d. City Council II.Public Involvement a. Public Meeting and Presentation b. Public Input/Opinion Period III.Overall Developments a. Regulator (MPCA) Discussions i. Expectations ii. Limit Projections b. Alternatives Development i. Preliminary Screening of Alternatives ii. Detailed Analysis of Selected Alternatives 1. Preliminary Sizing and Site Layout 2. Process Diagrams 3. Cost Opinions – Capital, O&M, NPW 4. Kepner-Tregoe Analysis (decision support tool) c. Technical Memorandums i. Basis of Design – Liquids and Solids ii. Alternative Screening – Liquids iii. Alternative Screening – Solids IV.Current Conclusions a. Liquid Trains i. West and East Facility - MBR 1. Upgraded and Expanded Preliminary Treatment 2. Membrane Bioreactors (MBR) 3. Disinfection and Space for Tertiary Treatment 4. Effluent Aeration 5. Administration and Storage Space 6. New Biofilters (Odor Control) b. Solids Trains i. East Facility – Consolidated Processing and Cake Landfilling 1. Expanded WAS Storage 2. New Thickening and TWAS Storage 3. New Dewatering Building 4. New Chemical (Lime) Stabilization Equipment with Loadout 5. New Biofilters (Odor Control) ii. West Facility 1. Expanded WAS Storage 2. Expanded Thickening and TWAS Storage 3. New Entrance / Loadout Road Otsego Wastewater Master Plan City Council Update – March 27, 2017 Initially Presented: Public Works Subcommittee – December 20, 2016 FIGURE 1: REGULATORY LIMIT PROJECTS – EAST WWTF DRAFT Notes: Not all limits are shown BOD and TSS limits could be increased through the Anti-Degradation analysis that will already be required for future flow increases greater than 200,000 gallons per day. A mercury concentration limit is anticipated but is not expected to influence alternative selection. Total nitrogen limits not provided by MPCA. Preliminary projections estimate an initial10 mg/L TN limit, with future TN limits in the range of 3 to 5 mg/L Otsego Wastewater Master Plan City Council Update – March 27, 2017 Initially Presented: Public Works Subcommittee – December 20, 2016 FIGURE 2: REGULATORY LIMIT PROJECTS – WEST WWTF DRAFT Notes: Not all limits are shown BOD and TSS limits could be increased through the Anti•Degradation analysis that will already be required for future flow increases greater than 200,000 gallons per day. A mercury concentration limit is anticipated but is not expected to influence alternative selection. Total nitrogen limits not provided by MPCA. Preliminary projections estimate an initial10 mg/L TN limit, with future TN limits in the range of 3 to 5 mg/L A Chloride concentration limit is projected based upon current WQSs and limited receiving stream dilution, but MPCA has formed a Work Group to determine if/how to implement Chloride standards state•wide. The Work Group's recommendation is anticipated in Q2 2017. "Off•site" chloride reduction strategies would be required to meet the potential chloride limit. Otsego Wastewater Master Plan City Council Update – March 27, 2017 Initially Presented: Public Works Subcommittee – December 20, 2016 Otsego Wastewater Master Plan Alternatives Pre-Screening I.Liquid Treatment Alternatives a. Selected for Detailed Analysis i. Expansion of oxidation ditch treatment at West WWTF ii. Expansion of oxidation ditch treatment at East WWTF iii. Membrane bioreactor treatment at West WWTF iv. Membrane bioreactor treatment at East WWTF v. Integrated fixed film activated sludge treatment at West WWTF vi. Integrated fixed film activated sludge treatment at East WWTF b. Considered, but Eliminated Alternatives i. No action (existing equipment / capacity) ii. Consolidation of treatment at existing East WWTF iii. Alternative disposal methods for treated effluent iv. Alternative discharge location – West WWTF v. Spray irrigation/Rapid infiltration basins vi. Sequencing batch reactors vii. Primary clarifiers with secondary treatment viii. Trickling filters ix. Anaerobic membrane bioreactor II.Solids Treatment Alternatives a. Selected for Detailed Analysis i. Split aerobic digestion and dewatering at both WWTFs ii. Transport of West WWTF thickened WAS for consolidated aerobic digestion and dewatering at the East WWTF iii. Transport of West WWTF thickened WAS for consolidated dewatering and chemical (lime) stabilization at the East WWTF b. Considered, but Eliminated Alternatives i. No action (current Class B land application with existing equipment / capacity) ii. Expansion of current biosolids handling approach iii. Split aerobic digestion with mobile dewatering press iv. Split aerobic digestion with consolidated permanent dewatering at either the West WWTF or East WWTF v. Transport of thickened solids to West WWTF for consolidated aerobic digestion or chemical (lime) stabilization and dewatering vi. Off-site, centralized stabilization and/or dewatering vii. Combined or split anaerobic digestion in any combination: 1. With primary clarifiers at both WWTFs 2. Without primary clarifiers and digestion of thickened WAS Influent Pumping Fine Screens (6mm) Screenings and Grit Disposal Preliminary Treatment Grit Removal Final ClarifiersAerobicAnoxic Anaerobic Re-AerationPost-Anoxic Denite Filters Phosphorus Filters UV Disinfection Effluent Aeration Waste Sludge to Solids Processing Discharge OXIDATION DITCH Return Activated Sludge (RAS) Internal Mixed Liquor Recycle PROS • TN/TP Limits • Relative Ease of Operations • Forgiving System • Stable Solids • Familiarity • Low Sludge Yield CONS • Larger Footprint • Requires Most Concrete • Limits Site Flexibility LIQUID TREATMENT OPTIONS City of Otsego Wastewater Treatment Master Plan Influent Pumping Fine Screens (2mm) Preliminary Treatment Grit Removal Final ClarifiersAerobicAnoxic Anaerobic Re-AerationPost-Anoxic Denite Filters Phosphorus Filters UV Disinfection Effluent Aeration Waste Sludge to Solids Processing Discharge INTEGRATED FIXED-FILM ACTIVATED SLUDGE Return Activated Sludge (RAS) Internal Mixed Liquor Recycle PROS • TP/TN Limits • Stable Nitrification • Retrofit/Small Footprint • Reduced SVI Variation CONS • Better Screening Required • Increased Headloss • Media Loss Influent Pumping Fine Screens (2mm) Preliminary Treatment Grit Removal Membranes AerobicAnoxicAnaerobic Re-AerationPost-Anoxic Denite Filters Permeate Pumping UV Disinfection Effluent Aeration Waste Sludge to Solids Processing Discharge MEMBRANE BIOREACTOR Mixed Liquor Recycle PROS • TN/TP Limits • No Phosphorus Filters • Smallest Footprint • High Quality Effluent • Perfect Clarifier • Reuse Potential CONS • Better Screening Required • Operational Complexity • Highest Equipment Maintenance • Most Equipment • Chemical Cleaning Screenings and Grit Disposal Screenings and Grit Disposal AEROBIC DIGESTION AND DEWATERING AT BOTH FACILITIES PROS • Proven technologies • Technology is similar, if not the same, as existing • Similar, dedicated technology at each facility • Reduces overall hauling requirements due to no thickening sludge transport • Significant re-use of infrastructure available at both facilities • Spreads footprint requirements between two facilities CONS • Extra equipment required to maintain redundancy at both facilities • Infrastructure for all technologies required at both sides • Additional labor requirements due to multiple solids treatment processes • Large overall footprint requirement due to repetition of processes at multiple facilities SOLID TREATMENT OPTIONS City of Otsego Wastewater Treatment Master Plan To Landfill To Landfill WAS Storage WAS Storage Thickening Thickening Aerobic Digestion Aerobic Digestion Dewatering Dewatering From Secondary Treatment Process and/or Final Clarifiers WEST > EAST> CONSOLIDATE DEWATERING AND CHEMICAL (LIME) STABILIZATION AT EAST WWTF CONSOLIDATE AEROBIC DIGESTION AND DEWATERING AT EAST WWTF PROS • Reduces two dewatering and stabilization processes into combined processes at a single facility, reducing overall footprint and equipment • Reduced infrastructure requirements through elimination of aerobic digestion in favor of chemical stabilization process • Proven technology • Similar, dedicated technology at each facility where required • Significant re-use of infrastructure available at both facilities • Class A biosolids for added ultimate disposal flexibility PROS • Reduces two aerobic digestion and dewatering processes into combined processes at a single facility, reducing overall footprint, equipment, infrastructure, and labor requirements • Proven technologies • Technology similar, if not the same, as existing • Similar, dedicated technology at each facility where required • Significant re-use of infrastructure available at both facilities CONS • Added hauling costs for transport of thickened solids from West to East WWTF • Large overall footprint requirement at a single facility (East) to handle solids addition from West WWTF • Technology new to City staff • Chemical dependent process CONS • Added hauling costs for transport of thickened solids from West to East WWTF • Large overall footprint requirement at a single facility (East) to handle solids addition from West WWTF To Landfill To Landfill WAS Storage WAS Storage WAS Storage WAS Storage Thickening Thickening Thickening Thickening Aerobic Digestion Dewatering Chemical (Lime) Stabilization System Dewatering WEST > WEST > EAST> EAST> Otsego Wastewater Master Plan City Council Update – March 27, 2017 Initially Presented: Public Works Subcommittee – February 15, 2017 FIGURE 3: LIQUID TRAIN ALTERNATIVES: BUILDOUT TOTAL COST SUMMARY DRAFT FIGURE 4: LIQUID TRAIN ALTERNATIVES: KEPNER-TREGOE ANALYSIS DRAFT Otsego Wastewater Master Plan City Council Update – March 27, 2017 Initially Presented: Public Works Subcommittee – February 15, 2017 FIGURE 5: SOLIDS TRAIN ALTERNATIVES: BUILDOUT TOTAL COST SUMMARY DRAFT FIGURE 6: SOLIDS TRAIN ALTERNATIVES: KEPNER-TREGOE ANALYSIS DRAFT Otsego Wastewater Master Plan City Council Update – March 27, 2017 Otsego Wastewater Master Plan Next Steps I.City confirms recommended alternatives II.Development of phasing for recommended alternatives III.Existing equipment assessment IV.Capital Improvements Plan V.Reports and Documentation VI.Adoption of Master Plan by City