Meadowcliffe Drive Erosion Control Project Toronto and Region Conservation Authority Environmental Study Report March 1, 2010 5 Shoreham Drive, Downsview, Ontario M3N 1S4 ACKNOWLEDGEMENTS The Toronto and Region Conservation Authority gratefully acknowledges the efforts and contributions of the following people participating in the planning and design phases of the Meadowcliffe Drive Erosion Control Project: Al Sinclair Meadowcliffe Drive Resident Barbara Heidenreich Ontario Heritage Trust Beth McEwen City of Toronto Bruce Pinchin Shoreplan Engineering Limited Councilor Brian Ashton City of Toronto Councillor Paul Ainslie City of Toronto Daphne Webster Meadowcliffe Drive Resident David Argue iTransConsulting Limited Don Snider Meadowcliffe Drive resident Janet Sinclair Meadowcliffe Drive Resident Jason Crowder Terraprobe Limited Jim Berry Toronto and Region Conservation Authority Joe Delle Fave Toronto and Region Conservation Authority Joseph Palmissano iTransConsulting Limited Larry Field Toronto and Region Conservation Authority Laura Stephenson Toronto and Region Conservation Authority Lindsay Prihoda Toronto and Region Conservation Authority Lori Metcalfe Guildwood Village Community Association Mark Preston Toronto and Region Conservation Authority Mike Tanos Terraprobe Limited Moranne McDonnell Toronto and Region Conservation Authority Nancy Lowes City of Toronto Nick Saccone Toronto and Region Conservation Authority Patricia Newland Toronto and Region Conservation Authority Paul Albanese City of Toronto Peter Xiarchos M.P.P Lorenzo Berardinetti’s Office Susan Scinocca Meadowcliffe Drive Resident Sushaliya Ragunathan M.P.P Lorenzo Berardinetti’s Office Timo Puhakka Guildwood Village Community Association Trevor Harris Meadowcliffe Drive Resident Tudor Botzan Toronto and Region Conservation Authority II EXECUTIVE SUMMARY Toronto and Region Conservation Authority (TRCA) continues to work towards ensuring healthy rivers and shorelines, greenspace and biodiversity, and sustainable communities. One key step in this process is the design and implementation of shoreline stabilization projects along the Scarborough bluffs. These projects serve to remediate erosion prone zones, and to rehabilitate and enhance key natural areas and community focal points. Several decades of important waterfront work has been carried out by TRCA in partnership with waterfront communities to protect and preserve the waterfront for present and future generations. TRCA is interested in undertaking remedial erosion control works along a portion of the Lake Ontario shoreline from Bellamy Ravine to Bluffers Park, one of the last unprotected sectors of the Scarborough bluffs in the City of Toronto. The project site spans approximately 1,400 m of shoreline from Bluffers Park, East Beach to Bellamy Ravine (also known as Gates Gully). At the request of several homeowners who expressed concern over the loss of property and the potential long-term risk to their homes, TRCA began monitoring erosion rates on Meadowcliffe Drive in 1985. Several studies have been completed along this shoreline sector; however the most significant report was a geotechnical report conducted on behalf of TRCA by Terraprobe in 2006, which identified acceleration in the erosion rate. This study concluded there would be a significant loss of property and infrastructure, as well as a risk to public safety if mitigative measures were not undertaken along the Meadowliffe shoreline sector. TRCA’s project objective is to provide long-term protection against erosion by reducing wave energy, protecting the toe of the bluffs from wave energy, stabilizing slopes and enhancing natural processes. As a consequence, risk to public safety and infrastructure will be reduced, passive recreational opportunities will be increased, and aquatic and terrestrial habitat conditions as well as aesthetics will be improved. TRCA has examined a number of alternatives to achieve these objectives including headland beach systems, groynes, and breakwaters. As part of the Class Environmental Assessment (Class EA) process, TRCA retained Shoreplan Engineering and Terraprobe to complete a detailed review and analysis of the existing conditions along the designated project area and assist with the development of alternative long-term remedial solutions to address the risk to public safety. Results of these investigations indicate that over the next 100 years, a substantial loss of highly valuable recreational, heritage and ecological land is projected, affecting numerous residential dwellings along the crest of the Scarborough Bluffs. In light of this information, a range of solutions were developed which recognized negative and positive attributes associated with each. To assist with the evaluation of the alternative options and provide input into the planning and design process, a Community Liaison Committee or CLC was formed. Composed of technical staff, stakeholders, provincial agency staff, community activists and interested members of the public, the CLC became an integral part of the Class EA process. Through a series of CLC meetings, a range of alternative options were considered, from traditional solutions such as cobble beaches and breakwaters. In addition to providing feedback on technical and economic considerations, the members provided great insight into the importance of preserving the Scarborough Bluffs. The preferred solution determined through the Class EA process is a shoreline treatment consisting of cobble beach anchored by a series of parallel headlands which will protect 600 metres (m) of eroding bluff below Meadowcliffe Drive. The headlands will be constructed with large (3-5 tonne) armour stones, measuring between 80 to 100 m in length and spaced 100 to 150 m apart. The area between the headlands will consist of rubble material covered with a III layer of beach cobble. The beach cobbles will be dynamically stable, and the profile shape will adjust to different wave conditions and water levels over time. The preferred solution also considers the potential need for a buttress at the base of the bluffs at the east end of the shoreline sector to reduce slope recession. TRCA identified five construction access options and evaluated these options to determine the preferred route. The preferred option is to access the site from the east via TRCA’s existing service road which provides shoreline access from the Guild Inn. TRCA has taken measures to address public concerns related to this route to ensure that all impacts are mitigated. Upon identifying the preferred solution, TRCA completed a detailed environmental analysis to determine any required mitigation measures. Information gathered through this process has informed the detailed design process. Working with representatives from City of Toronto, Ministry of Natural Resources, Fisheries and Oceans Canada, and Transport Canada, TRCA will prepare a screening report to fulfill the requirements of the Canadian Environmental Assessment Act. This screening report will facilitate the necessary federal approvals that will be required to implement the project. Capital funding for the proposed works has been identified in TRCA’s 2010 – 2014 budget, with works to be carried out between the period of July 1 – March 31 annually. Given the nature of coastal interventions 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, shoreline and slope recession. IV TABLE OF CONTENTS 1.0 INTRODUCTION ........................................................................................................................1 1.1 Relationship of the Undertaking to the Environmental Assessment Act.................................. 1 1.2 Purpose of the Undertaking .......................................................................................................... 3 1.3 Site Description .............................................................................................................................. 3 1.4 General Description of the Undertaking ...................................................................................... 5 1.5 Rationale for the Undertaking....................................................................................................... 6 2.0 BACKGROUND.......................................................................................................................... 7 2.1 History of the Problem................................................................................................................... 7 2.2 Identification of Previous Studies ................................................................................................ 9 2.2.1 Geotechnical Reports.................................................................................................................. 9 2.2.2 Planning Documents ................................................................................................................. 10 2.2.3 Aquatic and Terrestrial Habitat Reports .................................................................................... 12 2.2.4 Socioeconomic and Cultural Heritage Studies ......................................................................... 13 2.3 Justification of Conservation Authority Involvement ............................................................... 14 3.0 BASELINE ENVIRONMENTAL INVENTORY ..........................................................................