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Strategy to Control CSOs in Winnipeg . Presentation To. April 27, 2005. Outline. Background Existing System Response Possible Control Options Cost/Benefit Analysis 2003 CEC Recommendation Conceptual CSO Mitigation Plan . Background. 5 Interceptor Sewer systems

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Strategy to control csos in winnipeg

Strategy to Control CSOs in Winnipeg

Presentation To

April 27, 2005


Outline
Outline

  • Background

  • Existing System Response

  • Possible Control Options

  • Cost/Benefit Analysis

  • 2003 CEC Recommendation

  • Conceptual CSO Mitigation Plan

APEGM - CSO Strategy


Background
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


Wastewater treatment plants
Wastewater Treatment Plants

NEWPCC

WEWPCC

SEWPCC

ADWF = Average Dry Weather Flow (ML/d)

APEGM - CSO Strategy


Winnipeg s wastewater sewers
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


Combined sewers exist worldwide
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


Existing systems response
Existing Systems Response

APEGM - CSO Strategy


Receiving stream impacts
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


GM 200

APEGM - CSO Strategy


Illness risk
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


Control methods
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


Sewer separation
Sewer Separation

  • Estimated at about $1.5+ Billion (no inflation)

  • Very disruptive to community

APEGM - CSO Strategy


End of pipe treatment
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


End of pipe treatment1
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


Off line storage tanks
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


Deep tunnels
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


In line storage
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


Latent storage
Latent Storage

  • If these pipes are dewatered, storage could be available for inline storage

APEGM - CSO Strategy


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


Cso control benefits

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






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


Integration with other programs
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


Cost benefit trade off
Cost/Benefit Trade-off

APEGM - CSO Strategy


2003 cec hearings
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


Public notification information
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


Long term goal 4 overflows year
Long-term Goal: 4 Overflows/year

APEGM - CSO Strategy


Winnipeg s cso control plan
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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