East Don River Behind Clarinda Drive Erosion Control and Slope Stabilization Project

Toronto and Region Conservation Authority (TRCA) has proposed to undertake remedial works behind Clarinda Drive, in the City of Toronto. The purpose of this work is to protect private properties from valley slope instability related to erosion within a tributary of the East Don River behind Clarinda Drive.

Project Location

The project area is located in a City of Toronto and TRCA owned valley corridor northwest of the intersection of Sheppard Avenue East and Leslie Street within the Blue Ridge Park public greenspace. A tributary of the East Don River is located within the valley behind Clarinda Drive.

The watercourse within the study area was divided into two reaches based on channel gradient, form, and dominant geomorphic processes. The upstream Reach1 spans from the Blue Ridge Road stormwater outfall to the confluence with the first tributary at approximately 91 Clarinda Dr. The downstream Reach 2 spans from the first confluence to the second confluence, 230m downstream.

The East Don River behind Clarinda Drive Erosion Control and Slope Stabilization Project area.

Learn More About the Project

Project Background

Concerns regarding riverine and valley slope erosion behind Clarinda Drive were first identified to TRCA staff in 2009. Accelerated erosion and gullying were observed at this site related to the July 8, 2013 severe weather event. This storm resulted in several slope failures behind Clarinda Drive as well as damage to private residential properties at the top of the slope. Further inspection of the site revealed ongoing erosion issues within the channel including exposure of municipal sanitary infrastructure.

TRCA undertook various investigations to determine the extent of risk to essential infrastructure in this area over the long term. Based on the results of these investigations, it was determined that private residential dwellings, as well as City of Toronto owned sanitary infrastructure, were at risk from the hazards of erosion and slope instability should no remedial works be undertaken.

The degraded condition of ravine and tributary banks behind Clarinda Drive in Reach 1. Source: TRCA, 2019.

In order to address this risk, TRCA initiated the East Don River behind Clarinda Drive Erosion Control and Slope Stabilization Project (the “Project”) to provide long-term, low maintenance protection to at-risk essential structures adjacent to and within the project area. In an effort to address the highest risk areas first, work was divided into two reaches.

The degraded condition of the ravine and tributary banks behind Clarinda Drive in Reach 2. Source: TRCA, 2019.

This project is being planned in accordance with Conservation Ontario’s Class Environmental Assessment for Remedial Flood and Erosion Control Projects (amended 2013)(Class EA). The Class EA process is the approved planning approach for this type of work. The following diagram provides an overview of the Class EA process.

An overview of the planning process for Conservation Ontario’s Class Environmental Assessment for Remedial Flood and Erosion Control Projects (amended 2013). Source: TRCA, 2018.

The following alternative solutions were developed for Reach 1 & Reach 2 and were evaluated as part of the Class EA process for the Project. As part of the Class EA process, a ‘Do Nothing’ alternative was considered for each Reach:

Reach 1:

‘Do Nothing’ Alternative

Alternative 1 – Bank and Bed Protection

Alternative 2 – Bank and Bed Protection with Valley Slope re-grading

Alternative 3 – Pipe Flows

Reach 2:

‘Do Nothing’ Alternative

Alternative 1 – Reach Wide Bank Protection and Grade Control

Alternative 2 – Localized Bank Protection

The results of the Class EA evaluation led to the identification of Alternative 1 – Bank and Bed Protection in Reach 1 and Alternative 2 – Localized Bank Protection in Reach 2.

TRCA intends to file the Class EA Project Plan for Phase 2 for the 30 day review period in 2021.

*Please note the public review period has been extended from 30 days to 60 days given the disruption to many sectors due to the COVID-19 pandemic. TRCA will make every effort to provide alternative means of distributing reports for public review given the closure of public libraries.

Scope of Work

The objective of this project is to protect private properties on Clarinda Drive from valley slope instability related to accelerated erosion along this tributary of the East Don River.

Throughout 2021, TRCA intends to:

  1. File the Class EA Project Plan for a public review period *
  2. Develop detailed designs for remedial works for Reach 1 & Reach 2
  3. Secure necessary permits and approvals required to proceed to construction

*Please note the public review period has been extended from 30 days to 60 days given the disruption to many sectors due to the COVID-19 pandemic. TRCA will make every effort to provide alternative means of distributing reports for public review given the closure of public libraries.

Construction Information

TRCA is currently in the planning stages for the Project. Construction is tentatively planned to take place in 2022 – 2023, pending receipt of all necessary permits and approvals, and to the limit of available funding. Construction information will be updated following the completion of all planning activities.

Public Notices

  • Notice of Intent (NOI) – TRCA formally initiated the Project in 2020.
  • Community Liaison Committee (CLC):
    • CLC Meeting #1 – TRCA held a CLC meeting on March 11, 2020 and presented the results of the detailed investigations completed to date. Staff discussed the preliminary alternative erosion control and slope stabilization solutions for the Project area.

Progress Updates

March 2021

TRCA is working towards finalizing the Project Plan to file for the 60 day public review period.

Contact Us

For more information regarding this project, please contact:

Courtney Rennie, Senior Project Manager
Erosion Risk Management
Restoration & Infrastructure Division
101 Exchange Avenue, Vaughan L4H 0A3
Email: courtney.rennie@trca.ca
Phone: 416-661-6600 ext. 5523