The City of Toronto has completed a Municipal Class Environmental Assessment (EA) study for a new 4 kilometre (km), 900-750 mm diameter watermain that will address water servicing problems (low water pressure) and future servicing needs within the Downsview Area in the City of Toronto, Ontario.
The need for water servicing improvements in the Downsview area was identified following the completion of several municipal infrastructure studies in support of the Downsview Area Secondary Plan that is based on significant future development in the area. Further water system analysis in 2015, focused on the need for improving water pressure to meet current demands and reviewed a number of potential ways for meeting this need. Considering the expected growth and vision of the Downsview Area Secondary Plan, coupled with the results of the Preliminary Hydraulic Analysis conducted for this study, the Study Team identified the following Problem and Opportunity Statement as follows:
Problem: Significant near and long term growth is expected in the Downsview Area (the Study Area). Residents and businesses are experiencing low water pressure in the Study Area, particularly in the northwest portion (near Keele Street and Finch Avenue West). There is a need to enhance infrastructure for sustainable water supply and water pressure to service the current and projected future population within the Downsview Area.
Opportunity: Improve the overall level of water servicing to meet the needs of the existing customers and future projected growth. Co-ordination with other projects in the area to minimize impacts and provide efficiency.
In response to the above Problem and Opportunity Statement, the following Alternative Solutions were identified as part of the Municipal Class EA process :
- Alternative 1: Do Nothing
- Alternative 2: Re-aligned Pressure District, New Long Transmission Watermain and Keele Pumping Station Upgrade (Routes 2A, 2B and 2C are shown in Figure ES1)
- Alternative 3: Re-aligned Pressure District, New Booster Pumping Station and Short Transmission Watermain (Sites 3A, 3B and 3C are shown in Figure ES1)
- Alternative 4: Storage (Elevated Tank)
Alternatives 3C and 4 were screened out from further evaluation due to land area constraints and the inability to meet water servicing needs, respectively.
The comparative evaluation of alternative solutions concluded that the recommended preferred solution consists of siting and building a large watermain using local roads. The recommended preferred solution also requires upgrades at the existing Keele Pumping Station in order to deliver more water. Figure ES2 identifies the location of the recommended preferred alternative solution. The route and watermain size of the recommended preferred solution will be further investigated during the detailed design phase.
Potential Impacts and Recommended Mitigation Measures
Impacts related to construction of the recommended preferred solution (watermain and pumping station upgrades) will largely be limited to the duration and location of construction. Based on the recommended preferred solution (watermain route) and proposed construction techniques, construction is expected to have temporary environmental impacts. Impacts such as traffic flow and access disruptions will be mitigated by implementing standard construction and best management practices to minimize disruptions. These mitigation measures will be further confirmed and defined during the preliminary and detailed design phase by means of further studies and permit applications
Considering the above, it is recommended that:
- Following Municipal Class EA documentation filing and clearance, the recommended preferred solution, proceed to detailed design and obtain the required temporary and permanent easements and remaining approvals;
- During the detailed design phase, verify the proposed long transmission watermain sizing and route details;
- Mitigation measures including erosion and sedimentation controls, traffic management plans, etc. identified in Section 6 be expanded upon during the detailed design phase and implemented as part of construction; and,
- A detailed implementation phasing plan be developed for the proposed long transmission watermain and Keele Pumping Station Upgrades during the detailed design phase.