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Toledo Waterways Initiative and 185 mgd HRT Facility Wet Weather Partnership CSO Workshop Chicago, IL

09/14/06. B

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Toledo Waterways Initiative and 185 mgd HRT Facility Wet Weather Partnership CSO Workshop Chicago, IL

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    1. Toledo Waterways Initiative and 185 mgd HRT Facility Wet Weather Partnership CSO Workshop Chicago, IL Larry Jaworski - Black & Veatch F. Chris Middlebrough – City of Toledo, OH Carol L. Hufnagel – Tetra Tech

    2. 09/14/06 B&V - 2 Background Late 80’s & Early 90’s – Three CSO storage tunnels constructed. October 1991 – Original US/OEPA vs. Toledo lawsuit. July 2002 – Toledo voters approve ordinance to settle lawsuit. Consent decree. Start of Toledo Waterways Initiative.

    3. 09/14/06 B&V - 3 Consent Decree Requirements Discharge from Outfall 002 allowed only when flow exceeds 400 MGD Activated sludge treatment of all flows up to 195 MGD 60 MG EQ basin (reduced to 25 MG pending EPA approval); dewatered flows must receive activated sludge treatment 185 MGD high rate clarification facilities; may discharge only when flow exceeds 195 MGD & EQ basin is full Prohibited return of wet weather treatment solids to main plant headworks

    4. 09/14/06 B&V - 4 Bay View WWTP Flows Toledo, OH sewer system is 30% combined Bay View WWTP flows: 45 MGD dry weather 70 MGD average annual 130 MGD peak month 400 MGD peak hour Maximum flow through secondary treatment is approximately 195 MGD

    5. 09/14/06 B&V - 5 HRT Milestones February 2003 - Pilot Test Completed HRT - DensaDeg® vs. Actiflo ® UV Disinfection - Medium Pressure vs. LPHO 2005 – Construction Started October 2006 – Performance Testing of HRT 2007 – Begin Two-Year Effectiveness Study

    6. 09/14/06 B&V - 6 HRT Evaluation Factors Discharge Requirements Frequency of Use/Chemical Usage Pretreatment Needs Pumping Fine Screening Grit Removal Odor Control Startup & Shutdown Requirements Solids Handling Requirements Flexibility to Use for Primary & Tertiary Treatment

    7. 09/14/06 B&V - 7 HRT Pilot Test Actiflo ® - Kruger (Veolia Water) DensaDeg® - IDI

    8. 09/14/06 B&V - 8 Actiflo Design Considerations Fine Screening (< 1/4 inch openings) f (Hydrocyclone opening) Requires Grit Removal Thin Sludge (<0.5% solids); Volume ~ 2 to 3% of Influent Flow (= capacity of recirculation pumps) Media Recirculation & Cleaning System

    9. 09/14/06 B&V - 9 DensaDeg Design Considerations Fine Screening (< 1/2 inch openings) Concentrated Sludge (3 to 4% solids) Slower Startup Due to Reliance on Sludge Recirculation Potentially deeper settling compartment than Actiflo Less Consistent Performance Due to Ballast Media (Sludge) Variability

    10. 09/14/06 B&V - 10 HRT Intermittent Operation Issues Dry process startup; time required to establish process equilibrium Handling off-spec effluent Bringing parallel units on-line Maintaining a standby operational mode – necessary for Actiflo Dewatering to prevent nuisance conditions

    11. 09/14/06 B&V - 11 Other Uses for HRT Primary Treatment Derate to about 1/3 to ½ of Wet Weather Treatment Capacity Uses less Ferric Chloride than for Wet Weather Treatment Densadeg better than Actiflo due to solids thickening feature Dry Weather Tertiary Treatment Lowers TSS & phosphorus concentrations Improves chances of meeting 7-day limits when averaged with wet days

    12. 09/14/06 B&V - 12 HRT Costs Capital costs very close to the same in most cases Smaller footprint for Actiflo due to higher loading rates Less pretreatment required for DensaDeg If solids cannot be returned to plant influent, solids handling costs are lower for DensaDeg O&M costs slightly less for DensaDeg due mostly to lower pretreatment requirements

    13. 09/14/06 B&V - 13 Reasons for Selection of DensaDeg No additional sludge processing facilities required No additional fine screening facilities required, increasing amount of screening equipment to be maintained and screenings to be handled Rapid startup is not an issue Equipment is the same as existing equipment to service and maintain No need to maintain a “standby” mode No microsand and related maintenance and housekeeping issues

    14. 09/14/06 B&V - 14

    15. 09/14/06 B&V - 15 Bay View WWTP Layout

    16. 09/14/06 B&V - 16 Toledo, Ohio Bay View Wastewater Treatment Plant

    17. 09/14/06 B&V - 17 Toledo, OH DensaDeg® Layout

    18. 09/14/06 B&V - 18 Toledo, OH DensaDeg® HRT

    19. 09/14/06 B&V - 19 HRT Pipe Gallery & Sludge Pumps

    20. 09/14/06 B&V - 20 HRT and EQ Basin

    21. 09/14/06 B&V - 21 HRT Treatment Results Those were just a couple of graphs from the various performance runs. This table provides a summary of all the various runs. Normal = 27 mgd x 6 = 162 mgd total Peak Flow 1 = 185 mgd / 6 = 31 mgd (all units in service) Peak Flow 2 = 185 mgd / 5 = 37 mgd (firm peak flow) Average flow performance criteria = >50% TSS removal Peak flow performance criteria = >70% TSS removal except when TSS<40mg/L and >70% suspended CBOD removal Influent TSS ranged from 50 to 400 mg/L during week of testing. 40 mg/L ferric chloride & 2 to 3 mg/L polymer.Those were just a couple of graphs from the various performance runs. This table provides a summary of all the various runs. Normal = 27 mgd x 6 = 162 mgd total Peak Flow 1 = 185 mgd / 6 = 31 mgd (all units in service) Peak Flow 2 = 185 mgd / 5 = 37 mgd (firm peak flow) Average flow performance criteria = >50% TSS removal Peak flow performance criteria = >70% TSS removal except when TSS<40mg/L and >70% suspended CBOD removal Influent TSS ranged from 50 to 400 mg/L during week of testing. 40 mg/L ferric chloride & 2 to 3 mg/L polymer.

    22. 09/14/06 B&V - 22 First 6 Months of 2-year Effectiveness Study

    23. 09/14/06 B&V - 23 Wet Weather Treatment System Performance

    24. 09/14/06 B&V - 24 Two-Year Effectiveness Study Ongoing. Performance testing results verified. Continuing optimization. Have met final effluent limitations at flows up to 390 MGD. Including the big rain events of late August 2007.

    25. 09/14/06 B&V - 25 Facility Optimization Pilot study and performance testing used 40 mg/L or more FeCl3 and up to 3 mg/L of polymer… …while City now generally doses 10-30 mg/L FeCl3and 0.5-2 mg/L of polymer. A lot of DensaDeg® effluent sent to activated sludge system. Jar testing of recent events to further optimize FeCl3 to polymer ratios. Generally constant ratio whether dosing 45 and 1.5 mg/L or 15 and 0.5 mg/L (FeCl3 and polymer, respectively).

    26. 09/14/06 B&V - 26 Some Lessons Learned Density meters and blanket sludge depth detectors not necessary for intermittent operation Startup for intermittently operating facility – takes longer to work out glitches – longer warranty period is helpful Returning HRT effluent to secondary can inhibit nitrification Alkalinity consumption (HRT + nitrification) ? loss of effluent buffering capacity (pH concerns)

    27. 09/14/06 B&V - 27 HRT Construction Costs

    28. 09/14/06 B&V - 28 HRT Annual O&M Costs

    29. 09/14/06 B&V - 29 Questions ???

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