Twinning watermain safeguards drinking water supply to City of Toronto

Watermain will connect to existing valve chambers on street and adjacent to sidewalk in this very busy intersection

The Toronto water supply system supplies an average of about 1400 million litres per day via nearly 500 kilometres of mains ranging from 150 to 2500 millimetres diameter. The City pumps water from Lake Ontario to four water treatment plants and then to twelve separate pressure districts. Ten ground level reservoirs and four elevated tanks provide operating and emergency storage. A central facility controls pumping operations and system valves.

The City of Toronto has initiated a study to evaluate the water treatment and supply system’s ability to continually supply drinking water to the system service area. York Region draws water from the City of Toronto system and the Toronto/York Joint Optimization Study (JOS) completed by the City of Toronto and the Region of York in March 2006 identified water system requirements to supply future growth in both regions.

As part of their Joint Optimization Study, the City of Toronto has identified three watermains as requiring twinning to safeguard security of supply and improve system hydraulic performance. Consequently, the City requested proposals from qualified consultants for Route Studies, Class Environmental Assessments (EA), and Pre-Design Reports for watermains in the following locations: 4.5 kilometres of 1350 millimetre diameter watermain from Gerrard Street East to Eglinton Pumping Station along Pharmacy Avenue, 2 kilometres of 1500 millimetre diameter watermain on Ellesmere Road from Neilson Road to Markham Road, and 3 kilometres of 1050 millimetre diameter watermain from Scarborough Pump Station to St. Clair Avenue East and Midland Avenue.

Associated Engineering has been retained by the City to undertake this Route Study, Class EA, and Pre- Design Report in support of the upgrades to the trunk watermain system.

View of Eglinton Pumping Station from Pharmacy Avenue

Project Manager, Tony Barton advises, “As part of the the study we will identify three or more preferred watermain routes for each watermain. We will then analyze each route in light of the Class EA process. We will evaluate social, environmental, archaeological, and cultural impacts of each route and liaise with interested stakeholders and the general public through Public Information Centres (PIC’s).”

The study is presently ongoing and it is anticipated that the last of the Class EA Environmental Study Reports will be filed in Spring 2008 with the pre-design reports following the filing of the ESR’s.

All three sites are in heavily urbanized locations and the challenges in choosing suitable routes are not restricted to standard environmental criteria. Tony tells us, “Traffic consideration, both private and public (bus and subway), play an enormous impact not only in choice of route, but also in construction method. Most of the routes are through areas that have been developed over decades and the road right-of-way is already overloaded with utilities and other appurtenances. Add that to the local concerns about losing public open space and trees and the challenges rise significantly. Consequently, public opinion strongly favours tunneling despite the additional cost.”