Agenda Item No.: G.1.d.
Combined Sewer Overflow Control Strategy.
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Recommendation:
That this report be received as information.
Report Summary


This is an information report providing
background, development history, and
an outline of the Combined Sewer
Overflow Control Strategy.
At a cost of about $120 to $140 million,
the Combined Sewer Overflow Control
Strategy is a 20-year plan to mitigate the
environmental impacts of Edmonton’s
combined sewer system.
Report
INTRODUCTION
The City of Edmonton’s, Asset Management
and Public Works Department, Drainage
Services Branch, has developed a long-term
capital works implementation plan to reduce
the environmental impacts of the City’s
combined sewer system.
The Combined Sewer Overflow Control
Strategy was generated after five years of
study activity and several submissions to
Alberta Environmental Protection as
required by the City’s "Approval to
Operate". The Strategy was developed with
the assistance of numerous consultants and
with the involvement of the general public
and various stakeholder interest groups. A
special committee of Edmontonians, called
the Project Working Committee, each
representing a special interest group, was
struck in November 1997 to provide input to
the development of the Strategy.
The Combined Sewer Overflow Control
Strategy involves work to reduce the
spillage of untreated runoff and sewage to
Routing:
Delegation:
Written By:
March 24, 1999
File:99PWD031
the river. The plan will cost in the order of
$120 to $140 million with the bulk of the
expenditures to begin in the year 2005 and
to continue over a period of 15 years. A
re-evaluation of system performance and
any new environmental issues will be
undertaken as the Strategy nears completion.
If additional future controls are required,
additional program elements could be added
and the work extended.
THE PROBLEM
Located in the central, older parts of
Edmonton, combined sewers carry both
wastewater and stormwater runoff in the
same pipe. Combined sewer overflows
(CSO's) occur at one or more of the 19 CSO
locations in the sewer system during
significant rainfall or snowmelt events.
While combined sewer overflow accounts
for only about 2% of the City’s discharges in
a year (most of the City’s combined sewage
flow is fully treated at the Gold Bar
Wastewater Treatment Plant), they still have
a noticeable impact on the river.
With the completion of the ultraviolet light
effluent disinfection facility at Gold Bar in
1997, bacteria is killed during dry weather
flow conditions. Combined sewer overflows
are now the City’s largest contributor of
fecal coliform bacteria to the river.
Recognized as a health risk to recreational
river water users, bacteria from combined
sewer overflows has generally become the
single largest issue with combined sewer
overflow control programs nation-wide and
in the United States. Other water quality
parameters of concern include solids and
floatable materials (aesthetic impact) and, to
a lesser extent, nutrients (aquatic life).
Transportation and Public Works Committee
Al Maurer
Russell Barth/Kurt Sawatzky
Asset Management and Public Works
(Page 1 of 4)
G
1
d
Combined Sewer Overflow Control Strategy
THE STRATEGY
Phase A identifies the components being
recommended.
Strategy Components
Phase B, which could proceed after Phase A,
consists of various system storage elements
which are considered not as cost-beneficial
as the Phase A elements. Near the
completion of Phase A, a comprehensive
Strategy review would be conducted to
evaluate the merits of proceeding with
Phase B.
The Strategy is comprised of the following
components:
Early Action Control Plan
Involves low cost ways to better utilize
the existing sewer system.
Gold Bar Plant Upgrades
Involves upgrading the plant’s capacity
to provide enhanced primary treatment
of wet weather flows.
Strategy Benefits
The volume of combined sewer overflow
captured in the sewer system can be used as
a proxy of environmental benefit. The
average annual capture and treatment of wet
weather flows in the sewer system will rise
in:
 Phase A, from 56% to 86% capture, and
 Phase B, from 86% to 90% capture.
Tunnel Conveyance and Storage
Upgrade combined sewer system
conveyance and storage capacity will
bring more flow to the plant during and
after wet weather events.
Opportunistic Sewer System Separation
Opportunities to separate the combined
sewers into sanitary and storm sewers
arise when the infrastructure in older
neighbourhoods is rehabilitated.
The location of plan components is shown
on Attachment 1. More detailed information
can be obtained through the “Towards A
Cleaner River” website or other sources
listed at the end of this report.
Implementation Approach
A two-phased approach is planned for
implementation. Phase A, comprised of the
Early Action Control Plan, treatment plant
upgrades, and a number of sewer system
upgrades, will cost between $120 to $140
million, and is tentatively scheduled
between 1999 and 2020 (Attachment 2).
Reduction in the frequency of combined
sewer overflows can be used as a proxy of
aesthetic benefit. The average annual
combined sewer overflow occurrences will
reduce in:
 Phase A, from 89 to 46 occurrences, and
 Phase B, from 46 to 30 occurrences.
STRATEGY DEVELOPMENT
The development of the Strategy to control
combined sewer overflows has been a five
year process. It has taken over $2.5 million
and about 40 study assignments to develop
the Strategy. Numerous technical
workshops and Value Engineering sessions
brought forth the development of 64 control
options, which were refined and evaluated
until the recommended plan was arrived at.
(Page 2 of 4)
Combined Sewer Overflow Control Strategy
A large scale public outreach and
stakeholder involvement campaign was
conducted called ‘Towards A Cleaner
River’. Over 15,000 Edmontonians were
reached in 1997, 30,000 in 1998, and 30,000
have already been reached in 1999. In
addition to exhibiting at public events,
numerous stakeholder workshops and public
open houses were conducted.
A significant contribution to the
development of the Strategy was provided
by the Project Working Committee,
comprised of eleven members of the public,
each representing a stakeholder interest
group. The Project Working Committee has
provided key feedback to the Strategy
development process.
LEVEL OF SUPPORT
Edmontonian's opinions of the Strategy were
sought through the following venues:
questionnaires at two public open house
events, questionnaires within two issues of
the River Talk newsletter (distributed to
over 400 people), questionnaires and general
feedback obtained at numerous public
events (e.g. home shows, etc.), feedback
from briefings given to a number of
stakeholder interest groups (e.g.
Environmental Advisory Committee, etc.),
and feedback from the Project Working
Committee. Most responses received were
favourable to the Strategy. Most people
indicated that they are offended by the
notion of raw sewage entering the river, and
most are willing to accept the high cost of
control.
While the range of views on the Project
Working Committee is diverse, most support
the components within Phase A of the
Strategy. Some members feel that both
Phase A and B should be implemented,
while others question the merits of the Phase
B components when they compare the costs
against benefits that could be achieved. The
Project Working Committee is currently
preparing a report which will summarize its
perspectives on their involvement in the
development of Edmonton’s Combined
Sewer Overflow Control Strategy, and its
level of support for the Strategy.
Alberta Environmental Protection has
received submissions required in the City's
"Approval-to-Operate", including the “Long
Term Control Plan” report that outlined the
alternative plans under development on June
1, 1998. Alberta Environmental Protection
has responded favourably to pursuing plans
that are cost-effective and provide
significant environmental benefits.
Budget / Financial Implications
The inclusion of the Combined Sewer
Overflow Control Strategy in Drainage
Services’ 20-year financial planning horizon
has not resulted in a need to adjust customer
rate charges beyond the changes which were
previously planned. This is likely due to the
following factors:
 Early Action Control Plan activities
were included in previous capital
budgetting;
 20-year planning had previously
included some Combined Sewer
Overflow Control Strategy funding;
 the period for large expenditures on the
Plan is purposely planned for post 2005
when the large scale environmental
expenditures on tertiary treatment at the
Gold Bar plant will be complete; and
(Page 3 of 4)
Combined Sewer Overflow Control Strategy

implementation of the Plan is to be
distributed over a long period (about 15
years) to minimize funding impacts.
Legal Implications
The City of Edmonton is legally responsible
to develop and implement a plan to control
combined sewer overflows, as outlined in
the City's provincial "Approval-to-Operate"
(No. 95-MUN-117):
“3.1.8 The approval holder shall
develop:
(a)
a comprehensive Combined
Sewer Overflow Control Strategy
and a Wastewater Collection
System Management Strategy to
minimize the impact of
discharges on the North
Saskatchewan River, and a plan
for implementing these strategies
by June 1, 2000”.
“9.5.1 The approval holder shall
submit…
(c)
reports on the Combined Sewer
Overflow Control Strategy…
(iv) June 1, 1999 for Phase V:
Implementation”.

on-line Internet version anticipated
for April 9, 1999.
2. CSO Long Term Control Plan, UMA
Engineering Ltd., April, 1999.
3. Combined Sewer Overflow Control
Strategy Long Term Control Plan, City
of Edmonton, June 1, 1998 (report to
province).
4. A bibliography listing over 40
supporting reports, and any one of the
individual reports.
Others Approving this Report
Law Branch
Background Information Attached
1. Combined Sewer Overflow Control
Strategy – Location of Plan
Components.
2. Combined Sewer Overflow Control
Strategy – Recommended
Implementation Schedule.
Background Information Available on
Request
1. Towards A Cleaner River Website
 developmental version:
www.hotspur.com/river
(Page 4 of 4)