Wilket Creek Rehabilitation Project
The Wilket Creek Subwatershed of Don River
Wilket Creek is a second order tributary to the West Don River, it has a drainage area of 15.5 km2. The northern portion of the channel south to York Mills Road is a series of piped systems. South of York Mills Road the creek is an open channel for approximately 4.5 km and ending at its confluence with the West Don River.
About 80% of the Don River watershed is urbanized and 100% of the Wilket Creek subwatershed is urbanized. The southern portion of Wilket Creek is one of the few remaining open channel tributaries in the Don River catchment area. The remaining open flow tributaries (Wilket Creek, Taylor Massey Creek and Burke Brook) have sustained the longest and most dramatic hydrological change due to urbanization in all of Southern Ontario.
Watersheds with permeable ground and natural cover have a much slow response to rain events because most of the water is absorbed by soils, intercepted by plants and runoff is collected and stored in low lying areas. In urbanized watersheds the impervious nature of development promotes sheet flow directly to the storm system, the smooth surfaces of storm pipes increases flow velocity before outletting into the open channel.
Wilket Creek has no major tributaries, it receives water from local drainage, storm sewers and some ground water. The buried catchment area north of York Mills Road to Steeles is older and densely urbanized with few to no stormwater management controls. As such, flows in the watercourse rise and fall rapidly following precipitation, this "flashy" nature of the watercourse destabilizes the natural system because the channel must adjust to accomodate the increased flows. Destabilizing adjustments results in:
- Increased cross sectional area of the channel
- Downcutting into the channel bed
- Increased sediment loads due to the erosion
- Changes to typical channel characteristics such as meandering patterns
- Decreased quality and quantity of habitat
- Degraded water quality
- Loss of riparian vegetation (MOE, 2003)
Unfortunately, Wilket Creek has been observed to experience all these types of adjustments and watercourse degradation.
The Project Background
The Wilket Creek tributary of the East Don River was one of the watercourses that suffered a significant amount of damage as a result of the August 19, 2005 storm event. The City of Toronto subsequently retained TRCA in 2007 to manage, design and implement large-scale restoration works within Edwards Gardens, and 10 repair projects focused on infrastructure protection and public safety within Wilket Creek Park, to return the park system to a state of good repair.
Shortly following completion of the aforementioned restoration work, another severe storm event hit the Toronto area on June 23, 2008, damaging three of the sites in Wilket Creek Park recently repaired by TRCA. It was evident by this point that a comprehensive study and rehabilitation plan was required to provide long-term protection for municipal infrastructure and public safety within Wilket Creek Park.
In 2009, Toronto Parks, Forestry & Recreation (PF&R) and Toronto Water identified multi-year funding commencing in 2010 for the "Wilket Creek Channel within Wilket Creek Park Rehabilitation Study and Geomorphic Systems and Habitat Study" requesting TRCA's assistance to manage the Project on their behalf, including the implementation of any works recommended.
Following an initial assessment by Parish Geomorphic, the consulting firm retained by TRCA to assist with the study and design components of the Project, three areas within Wilket Creek Park were identified as requiring immediate attention due to the risk to municipal infrastructure and/or public safety. These sites are collectively referred to as Site 3, Site 6 and Site 7 by TRCA and the City of Toronto.
Map of all reaches and sub-project sites within Wilket Creek Park (Insert Map)
Given the anticipated length of time required to complete the study phase, the repair of Sites 3, 6 and 7 were recommended to be expedited for repair as emergency works, with the understanding that the designs for these sites will be in alignment with the overall strategy for Wilket Creek within Wilket Creek Park. TRCA retained Parish Geomorphic Ltd. to draft a design that will address the deficiencies at these locations. In light of the exposed sanitary sewer, Site 6 and Site 7 were addressed first and completed in May of 2012.
Site 3 will be completed in 2 phases. Phase 1 will include all channel works upstream of and including the replacement of the bridge crossing, while Phase 2 includes the sanitary sewer protection and associated channel works downstream.