Strategy to Control CSOs in Winnipeg

1. Strategy to Control CSOs in Winnipeg Presentation To April 27, 2005

2. Outline • Background • Existing System Response • Possible Control Options • Cost/Benefit Analysis • 2003 CEC Recommendation • Conceptual CSO Mitigation Plan APEGM - CSO Strategy

3. Background • 5 Interceptor Sewer systems • 3 Pollution Control Centres • 79 CSO locations • 231 Land drainage outlet • 101 to Red and Assiniboine • 2 Major Rivers APEGM - CSO Strategy

4. Wastewater Treatment Plants NEWPCC WEWPCC SEWPCC ADWF = Average Dry Weather Flow (ML/d) APEGM - CSO Strategy

5. Winnipeg’s Wastewater Sewers Older parts of the City (pre 1960) Approximately 30% of City has combined sewers CSO – dilute mixture of sewage and land drainage APEGM - CSO Strategy

6. Combined Sewers Exist Worldwide • Many European cities have combined sewers • control strategies being developed • In North America, about 850 communities have combined sewers • e.g., Boston, Chicago, San Francisco • In Canada, cities include Halifax, Quebec City, Montreal, Toronto, Edmonton, Vancouver • In Manitoba, portions of Winnipeg, Brandon and Selkirk sewer systems have combined sewers. APEGM - CSO Strategy

7. Existing Systems Response APEGM - CSO Strategy

8. Receiving Stream Impacts • On average, CSOs occur 18 times per recreation season (May 1 to Sept 30) • Overflows are wet weather driven • During dry weather, all sewage is intercepted and conveyed to WPCCs for treatment • ~ 1% of total annual sewage is lost to overflows • Effects of CSOs on River Quality relate to: • Microbiological water quality • Aesthetic quality (Visual) APEGM - CSO Strategy

9. GM 200 APEGM - CSO Strategy

10. ILLNESS RISK • CSO Advisory sub-committee concurred in following: • CSO control will be costly and the benefits are subjective • There are many reasons to consider CSO control • CSOs should not be considered a significant public health issue … • CSO control is fundamentally a public policy and a regulatory compliance issue. APEGM - CSO Strategy

11. Control Methods • Several control options possible: • Separation • End-of-pipe treatment • Storage and dewatering • Off-line tanks / Tunnels • In-line storage Target of 4 overflows per season common practice in USA APEGM - CSO Strategy

12. Sewer Separation • Estimated at about $1.5+ Billion (no inflation) • Very disruptive to community APEGM - CSO Strategy

13. End-of-Pipe Treatment • Vortex Solids Separator (VSS) • Very costly, large structure, requires land at outfalls • Requires chemicals, operational considerations • NOT recommended APEGM - CSO Strategy

14. End-of-Pipe Treatment • Retention Treatment Basins (RTBs) • Very costly, large structure, requires land at outfalls • Requires chemicals, operational considerations • NOT recommended APEGM - CSO Strategy

15. Off-line Storage Tanks • This will comprise large, near-surface tanks located at the end of the combined sewer trunks • This method is used in: • Saginaw, Mich. • Toronto, Ont. • Sarnia, Ont. APEGM - CSO Strategy

16. Deep Tunnels • Large tunnels could be used to store and convey combined sewage to WPCCs for treatment • This method is used in: • Chicago, Ill. APEGM - CSO Strategy

17. In-line Storage Large old trunk sewers offer potential storage for combined sewage during smaller storms Relief sewers constructed for basement flooding also provide large volumes of potential storage Trunk Sewer Relief Sewer 7.55 ft 9.75 ft APEGM - CSO Strategy 9.0 ft

18. Latent Storage • If these pipes are dewatered, storage could be available for inline storage APEGM - CSO Strategy

19. In-line Storage • In-Line storage involves retaining wet-weather flow in the pipe for small rainstorms • The stored wastewater is dewatered at a controlled rate and sent to WPCC • If the rainstorm threatens basement flooding, all flow is released to river • Needs Local Testing • Sediment deposition • Odours • Minimize risk of basement flooding (reliability/liability) • Has been used successfully in other jurisdictions • Cleveland and • Detroit In-Line Storage Inflatable Dam To Interceptor APEGM - CSO Strategy

20. With CSO Separation With CSO Control With Effluent Disinfection With Effluent Disinfection With Effluent Disinfection 200 200 200 200 200 200 200 CSO Control Benefits APEGM - CSO Strategy

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25. Overview of Plan Tunnel Storage (Zero overflows) In-line Storage plus Distributed Storage and Transfers plus Off-Line Storage Complete Sewer Separation In-line Storage plus Distributed Storage and Transfers Available In-line Storage Disinfection at WPCCs CSO Control Options APEGM - CSO Strategy

26. Integration with Other Programs • Basement Flood Relief • Combined Sewer Renewal • Potential Opportunities • Oversizing of proposed relief pipes for storage • Allowance for localized separation • Cleaning of trunk sewers for storage • New Developments APEGM - CSO Strategy

27. Cost/Benefit Trade-off APEGM - CSO Strategy

28. 2003 CEC Hearings • Clean Environment Commission (CEC) held public hearings in January and April 2003, and recommended Combined Sewer Overflow Reduction 7. The City directed to shorten the timeframe to complete its CSO plan a 20 to 25 year period. 8. The City directed to reduce CSOs by instrumenting outfalls, adjusting weirs, accelerating combined sewer replacement, advancing the pilot project …within two years. Public Notification System 9. The City directed to develop and implement a notification system to inform the public whenever there is a release of raw sewage to the local Rivers … • Provincial Implementation(to be confirmed) • Accept City plan to reduce overflows to 4/year on average • Complete CSO plan by 2030 APEGM - CSO Strategy

29. Public Notification & Information Keep our rivers clean! What goes into the sewer can end up in our rivers. Responsible at source control APEGM - CSO Strategy

30. Long-term Goal: 4 Overflows/year APEGM - CSO Strategy

31. Winnipeg's CSO Control Plan • City’s current CSO control plan reflects many important considerations: • 2003 CEC Hearings recommendations • Manitoba conservation guidance and priorities • Consistency with prevailing international practice • Understanding of benefits and costs • Fiscal responsibility and environmental stewardship • Initiation of near-term actions to reduce CSOs • Confirmation of long-range control program APEGM - CSO Strategy

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