Patterson Creek Sanitary Infrastructure Protection Project

Toronto and Region Conservation Authority (TRCA), in partnership with the Regional Municipality of York, is preparing to implement infrastructure protection works along Patterson Creek, in the City of Richmond Hill, in order to provide long-term protection to at-risk sanitary sewer infrastructure.
Project Location

The Patterson Creek Sanitary Infrastructure Protection Project is located along two distinct sections of the Patterson Creek watercourse, situated within the Don River watershed.

Both project areas are located northeast of Bathurst Street and Carrville Road, in the City of Richmond Hill. Sites I-075 and P-1005 are located within private and municipally owned property at the rear of Grist Mills Park. Sites I-070 and P-107 are situated within municipally owned property at the rear of the Richvale Community Centre and Athletic Park and St. Charles Garnier Catholic School. The areas will be referred to as Grist Mill and Richvale sites respectively.

map showing the location of the project
Figure 1. Project location map. Source: TRCA, 2020.
Learn More About This Project

Project Background

In 2011, TRCA developed the Infrastructure Hazard Monitoring Program (IHMP). The purpose of the IHMP is to ensure timely identification of risk to infrastructure due to watercourse activity (i.e. channel migration, widening, etc.) and efficient prioritization and mitigation of such risks in collaboration with stakeholders.

The IHMP broadly divides watercourse erosion risks into two types of sites: intersection sites to assess the risk of bed erosion where the sewer crosses a watercourse, and proximity sites to assess the risk of bank erosion and lateral channel adjustments in close vicinity to the infrastructure. Intersection sites are categorized using an “I-” identifier, while proximity sites are categorized using a “P-” identifier.

In regards to this particular project, the infrastructure at risk includes a 525 mm diameter sanitary main, owned by the Regional Municipality of York, which was installed in October 1971. Over the past 49 years, Patterson Creek naturally migrated within the flood plain and has shifted over or in close proximity to the sanitary main and associated maintenance holes. As such, the IHMP identified Sites I-075, P-1005, I-070, and P-107 as requiring remedial works where sanitary infrastructure is exposed or at the immediate risk of exposure within Patterson Creek. Remediation works are necessary at these sites to protect the infrastructure and the environment from sewer exposure.

Exposed maintenance hole chimney on the east bank of Patterson Creek at Site I-075
Figure 2. Exposed maintenance hole chimney on the east bank of Patterson Creek at Site I-075. Source: TRCA, 2018.
Exposed maintenance hole chimney on the east bank of Patterson Creek at Site P-1005.
Figure 3. Exposed maintenance hole chimney on the east bank of Patterson Creek at Site P-1005. Source: TRCA, 2018.
Displaced concrete weir (proposed to be removed) at the upstream portion of Site P-107 where the sanitary line is at risk of exposure.
Figure 4. Displaced concrete weir (proposed to be removed) at the upstream portion of Site P-107 where the sanitary line is at risk of exposure. Source: TRCA, 2018.
Erosion at Site I-070 where the sanitary line crosses the watercourse and is at risk of exposure.
Figure 5. Erosion at Site I-070 where the sanitary line crosses the watercourse and is at risk of exposure. Source: TRCA, 2018.

In 2017, TRCA retained Palmer to conduct a scoped geomorphic and environmental impact assessment of the proposed project area. Following completion of the study, detailed designs utilizing natural channel design principles were developed throughout 2018.

The remedial designs have been refined through consultation with multiple Regulatory agencies to provide adequate protection to sanitary infrastructure, while at the same time providing an overall ecological benefit to the area. Implementation will be completed in two phases as described the following sections.

Funding for the geomorphic study and detailed design development of these remedial works has been provided through the Clean Water and Wastewater Funding (CWWF) Grant Program from Infrastructure Canada and Infrastructure Ontario. For more information regarding the CWWF program, please click here.

Scope of Work 
  • Geomorphic study and Environmental Impact Statement (completed in 2017)
  • Development of detailed design (completed summer – winter 2018)
  • Obtain all necessary and approvals to proceed to construction (winter 2018 – spring 2019)
  • Phase 1: tree removals at Grist Mill and Richvale sites (late March 2020)
  • Phase 2: construction of remedial erosion control works at Grist Mill and Richvale sites (June to November 2020)
Construction Information

What can you expect during Phase 1? 

  • Phase 1 tree removals will take place in late March 2020 for a 2 week duration
  • Forestry crews will be working during the day from Monday to Friday
  • To ensure public safety while crews are working, trails within the Richvale site may be temporarily closed for a few hours a day
  • Access to Grist Mill Park and the Richvale Athletic Park will not be affected

For your safety, please respect all posted construction signs and stay clear of the work areas and equipment. Thank you for your patience and cooperation.

More information regarding the Phase 2 work area, access routes, trail closures, tentative schedule and construction highlights will be provided in spring 2020.

Public Consultation

The project has been developed under a Schedule A+ Municipal Class Environmental Assessment.

TRCA will notify all residential and commercial properties within the vicinity of the project area through a hand delivered Notice of Construction (NOC). Project information signs, which will include details regarding trail closures, will be installed at the adjacent park entrances and/or access route points.

Please see the link below to view the public consultation documents for this project:

Project Updates

Week of March 9, 2020

Phase 1 of the project, which involves tree removals, will take place in late March 2020 for 2 weeks. The tree removals are required to facilitate Phase 2 remedial works, which are scheduled for summer 2020. These works are required to protect sanitary infrastructure and the environment from the risk of sewer exposure in Patterson Creek.

Phase 2 of the project includes the improvement of park amenities and local habitat following the construction of remedial works. Local improvements include the restoration of the Grist Mill Park bocce court, trail improvements and installation of 1000 native plants across the community.

Week of June 24, 2019

Implementation at I-070/P-107 and P-1005/I-075 has been postponed to summer 2020, pending the receipt of all permits and approvals. Please check back here for further updates closer to construction.

Contact Us

The Project Planning Team is located at TRCA’s Boyd Field Centre Office in Vaughan:

Restoration and Infrastructure Division, Erosion Risk Management
9755 Canada Company Avenue
Vaughan, Ontario
L4H 0A3

For more information regarding this project, please use the contact details outlined below:
Phil Wolfraim, Project Manager 
Erosion Risk Management
Engineering Projects, Restoration & Infrastructure Division
phil.wolfraim@trca.ca
416.661.6600