2250 mm Trunk Watermain from Horgan WTP to Ellesmere Reservoir – Class EA and Route Selection Study


Client: City of Toronto
Services: Class EA and Route Selection Study including Public Consultation Services

Key Features:
• A complex project, with numerous alignments available, the prevalence of environmental features and the level of public and agency concern. The team completed a detailed inventory of environmental conditions, assessed a number of alternative alignments and methods of construction (e.g. tunnel vs. open-cut).
• Following a balanced and objective review and a rigorous public consultation process, the preferred route (Route D) was identified.
• The evaluation of alternatives, associated impacts, mitigative measures, cost estimates and the selection and rationale behind the preferred alignment was documented in a comprehensive Environmental Study Report (ESR). Preliminary design drawings were also

Based on year 2031 projections, Toronto and York Region identified the need for a new transmission watermain from the F.J. Horgan Filtration Plant to Ellesmere Reservoir and Pumping Station to serve Pressure District 1E in Toronto and southern areas of York Region.


In the early 1970’s two trunk watermains were designed by CFA and constructed between the Horgan Plant and Ellesmere Reservoir (2100 and 1350 mm diameter).

The preferred route selected deviations from the alignment of the two existing transmission mains, strategically selected to take advantage of existing easements, where possible, reducing new property requirements and providing some additional buffer from residential lots in localized areas.

Extensive consultation activities included notices, information bulletins, specific meetings with agencies, local residents and interest groups and two public information centres. These helped address public concerns, evidenced by the fact that the EA document received MOE approval despite some Part II Order requests.