Patterson Creek Sanitary Infrastructure Protection Project – Completed

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Toronto and Region Conservation Authority (TRCA), in partnership with the Regional Municipality of York, completed infrastructure protection works along Patterson Creek to provide long-term protection to at-risk sanitary sewer pipes and maintenance holes.

Project Location

The Patterson Creek Sanitary Infrastructure Protection Project was made up of four infrastructure sites along two distinct sections of the Patterson Creek watercourse, situated within the Don River watershed. Therefore, infrastructure sites were grouped by proximity for the work.

Sites I-075 and P-1005 are located at the rear of Grist Mill Park. Sites I-070 and P-107 are located at the rear of the Richvale Community Centre and Athletic Park and St. Charles Garnier Catholic School. The project areas will be referred to below as the Grist Mill and Richvale sites, respectively.

map showing the location of the project
Location of the two project sites, northeast of Bathurst Street and Carrville Road, in the City of Richmond Hill. Source: TRCA, 2020.

Scope of Work

  • Start Date: March 2020
  • End Date: Spring 2021

The Patterson Creek Sanitary Infrastructure Protection Project was considered high priority due to the risk to sanitary sewer lines and/or maintenance holes posed by the erosion hazards. The scope of work included the following:

  • Geomorphic Study and Environmental Impact Statement (completed in 2017)
  • Development of detailed design (completed during Summer to Winter 2018)
  • Obtain all necessary and approvals to proceed to construction (completed during Winter 2018 to Spring 2019)
  • Tree removals at Grist Mill and Richvale sites (March 2020)
  • Construction of remedial erosion control and infrastructure protection works at Grist Mill and Richvale sites (June to August 2020)
  • Restoration including seeding disturbed areas, tree and shrub planting, and construction of a new bocce court (Summer 2020 to Spring 2021)

The Clean Water and Wastewater Funding (CWWF) Grant Program provided funding for the geomorphic study and remedial works detailed design development. For more information regarding the CWWF program, run by Infrastructure Canada and Infrastructure Ontario, please click here.

Grist Mill Site

Photos showing the I-075 site before and after construction
Site I-075 before (left) had a partially exposed sewer and concrete rubble along the east bank. After (right) shows the channel moved further from the maintenance hole and a vegetated revetment with cedar sweeps installed along the bank. Source: TRCA, 2020 & 2021.
Photos showing the P-1005 site before and after construction
Site P-1005 before (left) had an exposed maintenance hole along the east bank. After (right) shows the channel moved further from the maintenance hole and an enhanced riffle pool sequence with cedar sweeps installed along the bank. Source: TRCA, 2020 & 2021.
New bocce court constructed at Grist Mill Park in Richmond Hill
The bocce court in Grist Mill Park was rebuilt and enhanced as part of the restoration works. Source: TRCA, 2021.

Richvale Site

Photos showing the P-107 site before and after construction
Site P-107 before (left) had a failed concrete grade control weir which was removed. After (right) shows the vegetated stone revetment installed for sewer protection, woody debris habitat features, and enhanced riffle pool sequences. Source: TRCA, 2020 & 2021.
Photos showing the I-070 site before and after construction
Site I-070 before (left) had an at-risk sewer crossing. After (right) shows installed riffle bed protection and vegetated revetments. Source: TRCA, 2020.