Royal Rouge Trail Erosion Control Project
Background of Project
In 1989, a homeowner contacted TRCA to express concern over the instability of the valley wall and the potential long-term risk to their home. After several small-scale studies and minor erosion control works in the years following the initial identification of the problem, TRCA completed a detailed slope stability and erosion risk assessment to confirm the cause(s) and extent of the problem, the results of which indicated that major erosion control work was required to provide long-term protection for the ten (10) residential properties along Royal Rouge Trail within the study area.
Project Objectives
The key project objective is to provide long-term protection for the residential properties in the affected area while maintaining the health and integrity of the valley corridor. As a result, risk to public safety and existing structures will be reduced, and long-term, terrestrial habitat conditions will be improved. TRCA has examined a number of alternatives to achieve these objectives including slope trimming, intense vegetation of the slope, soil retaining structures, and drainage improvements.
Planning Mechanism for the Undertaking
TRCA must conduct its remedial flood and erosion control projects in accordance with the Environmental Assessment Act (EAA). Recognizing that common elements exist in addressing flood and erosion problems, a more efficient approach to environmental assessment was developed by Conservation Ontario for all conservation authorities known as the Class Environmental Assessment for Remedial Flood and Erosion Control Projects (Class EA). The Class EA approach is considered a suitable means for the planning of remedial flood and erosion control projects because it provides a consistent, streamlined process that ensures compliance with Environmental Assessment Act (EAA) requirements.
In the fall of 2010, TRCA will submit the Environmental Study Report in support of the Royal Rouge Trail Erosion Control Project for approval by the Ministry of the Environment under subsection 7 (1) of the Environmental Assessment Act (EAA).
Public and Agency Consultation
The Class EA process provides that all views respecting a proposed remedial flood or erosion control project be taken into consideration during the planning and design of remedial flood and erosion control projects. The formation of a Community Liaison Committee (CLC) has allowed concerned citizens, local interest groups and non governmental organizations to voice issues of public concern as well as assisted in the planning and design process of the project.
Through a series of CLC meetings, a range of alternative options have been considered, which included traditional solutions such as intense vegetation, trimming, and retaining wall structures. In addition to providing feedback on technical and economic considerations, the members provided great insight into the importance of preserving the Rouge Valley Corridor. The CLC assisted with selection of a preferred alternative.
The Project
The project area has been divided into two sectors based on the type and extent of the erosion and instability processes along the valley wall. The project area was divided into the following two sites:
- Site A – Nos. 30 to 40 Royal Rouge Trail
- Site B – Nos. 42 to 48 Royal Rouge Trail
The preferred solution determined through the Class EA process was trimming and intense re-vegetation for Site A, and a “green” retaining structure that allows for the most cost-effective use of land while achieving maximum aesthetic and environmental value for Site B. Primary considerations for these selections included:
- Providing adequate long-term stability of the valley wall and protection of public safety
- Compatibility with, and minimizing impacts on, the surrounding physical and biological environment
- Providing terrestrial enhancements to the greatest extent possible
- Cost effectiveness
- Public opinion
Capital funding for the proposed works has been identified in TRCA's 2010 - 2011 budget. Pending the successful completion of the Class EA process, and the receipt of all necessary approvals, implementation of the preferred remedial measure is anticipated to commence in the late fall of 2010,
Given the nature of remedial works over the past 50 years across North America, TRCA anticipates that an adaptive management approach will be necessary, to allow modifications to the overall design based on continued monitoring and evaluation of the built structures, and slope recession.
For more information, please contact Patricia Newland, Project Manager at (416) 392-9690 or pnewland@trca.on.ca.
