Drainage problems in the Craigleith area were documented in 1993, following which Municipal Drains were created.
Staff report PDS.21.08 noted that Stormwater capacity constraints were documented in the 1993 Craigleith Camperdown Subwatershed study. In response to concerns about the existing stormwater drainage system, three Municipal Drains were established in 1996. The Blue Mountain Outlet and Diversion Drain divert flows from Watercourse 7 to Watercourse 8 and upsizes the Watercourse 7 culvert under Highway 26. The Ford Outlet Drain included upsizing the Watercourse 9 culvert under Highway 26. The Watercourse 8 culvert under Highway 26 was not upsized or reconstructed as part of the original Municipal Drainworks, although additional water was diverted from Watercourse 7 to Watercourse 8 and the culvert. While drainage improvements were made in 1996, the improvements did not create sufficient capacity to convey the Regulatory event (the greater flow from the 1:100-year storm), particularly on Watercourse 8.
With the continued development of the Craigleith area, there is a need to address drainage concerns at the base mountain's base Craigleith Landowner Group has development permissions for lands above the Ford Outlet Drain, Blue Mountain Diversion Drain, and the Blue Mountain Outlet Drain and has petitioned the Town through the Drainage Act for improvements to these drains, increasing the outlet capacity to Georgian Bay. The Craigleith Landowner Group will pay all associated construction costs. This will alleviate the existing deficient capacity in the downstream systems of these drains to improve overall drainage and provide relief for existing flooding conditions in the Craigleith Area. Existing flooding conditions of the watercourses and the analysis of flooding mitigation work were conducted by Crozier Consulting Engineers and reviewed/verified by Tatham Engineering and W.T Infrastructure.
The W.T. Infrastructure Engineers report provides a plan to drain lands to a sufficient outlet in accordance with the provisions of the Drainage Act. Excess flows from Watercourse 7 (the Blue Mountain Outlet drain) and Watercourse 9 (the Ford Outlet drain) will be diverted to Watercourse 8 (the Blue Mountain Diversion drain), and the capacity of the Blue Mountain Diversion drain will be increased to allow conveyance up to and including the Regulator event flows.
Stormwater management controls are also incorporated in the proposed developments as required by the Ministry of Environment Conservation and Parks (MECP).