Eliminating Combined Sewer Overflows from

Vancouver’s Waterways Brian Crowe, P.Eng.

Director of Water, Sewers & District Energy City of Vancouver

April 16, 2014

Vancouver’s Strategy to Eliminate CSOs

• How a combined sewer system operates

• System performance & vulnerabilities

• Separation mandate – Progress and current pace

• Strategy – Public side separation through lifecycle replacement – Additional strategies/emerging best practices

• Benefits and Opportunities

Stanley Park 2011

Primary Driver - Environmental Improvement

Strategy to Eliminate CSOs: Timely Reconstruction of the Sewer System

Transitioning from a

combined system (sewage and runoff in one

pipe) to a separated system (sewage in one pipe, runoff

in another pipe)

Combined Sewer Overflows

Combined Sewage to

Treatment Plant

Stormwater & Runoff

Combined Sewage Overflow

Capacity Limits at Treatment Plant or in Sewer Interceptors

Sanitary Sewage

Construction of the English Bay Interceptor Sewer – 1930’s

Progress in eliminating untreated sewage discharges in Metro Vancouver

Current CSO Locations

Combined Sewer Overflows During Storms

Additional Vulnerabilities of Combined System

• Storm-induced overland flooding • Combined-sewage backups into

buildings • Sensitivity to climate change

impacts

LWMP (Provincial Regulation) commits us to:

• Eliminate CSOs by 2050

• Separate combined sewers

at an average rate of 1% annually

Vancouver’s Commitment to Eliminate CSOs

Progress at Eliminating Overflows

05000

1000015000200002500030000

Discharge Volume

(million L)

1990 2000 2010 2020 2030 2040 2050

CSO Reductions

Projected Separation – about 60% complete by 2020

Infrastructure Lifecycle Management

Collapsing Sewer Main

Infiltration

Theoretical Lifecycle Replacement Projection (Why 2050?)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0

50

100

150

200

250

300

350

Mai

n Se

wer

Sys

tem

Sep

arat

ion

Mai

n Se

wer

Rec

onst

ruct

ion

(km

)

Required Main Sewer Reconstruction by Decade

Required main sewer reconstruction based on life cycle analyses

1% Replacement Rate of Main Sewer System (km)

Main sewer system separated

Tools - Construction Strategies

• Disconnecting roof leaders

• Private property separation

• Green roofs • Rainwater harvesting • Permeable pavement • Rain gardens • On-site storage, etc.

Additional strategies – Integrated Stormwater Management

Signs of Progress!

Future State – Fully Separated Homes – Rainwater & Sewage as Resources

Sewage as a Resource (Energy Recovery)

Thank You

Thank You