Fishleigh Drive Erosion Control Project

Toronto and Region Conservation Authority (TRCA) is undertaking remedial erosion control works along a portion of the Lake Ontario shoreline located at the base of the Scarborough Bluffs below the eastern extent of Fishleigh Drive in the City of Toronto.

Project Location

Fishleigh Drive is located west of Bluffer’s Park, atop the table lands of the Scarborough Bluffs along the north shore of Lake Ontario in the City of Toronto.  The area of concern is the eastern extent of Fishleigh Drive, directly below 81 and 83 Fishleigh Drive.

Project location. Source: TRCA, 2017.

 

Aerial photograph of site
Site photograph. Source: TRCA, 2014.

Background

The Scarborough Bluffs are located on the northern shore of Lake Ontario in the City of Toronto.  They extend approximately 15 kilometers from Victoria Park Avenue in the west to Highland Creek in the east.  A remnant of the shoreline of Lake Iroquois, the Scarborough Bluffs have formed over 100,000 years from sedimentary deposition.  Although the stratigraphy varies along the 15 kilometer stretch, the bluffs are primarily composed of silty clay at lake level, overlain with silty sand and sand, and capped with till.  Since their formation, the bluffs have been actively eroding.  The practice of stonehooking (removing large rocks from the bed of the lake) in the early 1900’s is credited with accelerating the erosion process (City of Toronto, 2012).  The dual effect of wave action at the base of the bluffs, coupled with the sediment transfer of the eroded material, has created over-steepened slopes.  In addition to wave action and the subsequent sediment transfer, the processes of frost-jacking, wind, surface runoff and groundwater seepage also contribute to erosion (TRCA, 2011).

Previous Erosion Control Work

In 1980-1981, Geocon Inc. carried out an extensive erosion control study of the Scarborough Bluffs as a whole.  This study identified Fishleigh Drive as one of the sectors along the Scarborough Bluffs in need of erosion control.  In response to this, TRCA retained Keith Philpott Consulting in 1987 to provide design options for remedial shoreline protection works.  In 1988, Terraprobe Limited was retained to conduct subsurface investigations and establish the Long Term Stable Slope Crest (LTSSC).  Later that year, based on recommendations and analysis from Keith Philpott Consulting and Terraprobe Limited, TRCA produced an Environmental Study Report under the Class EA for Water Management Structures (now Remedial Flood and Erosion Control Projects).  This report, entitled Fishleigh Drive Erosion Control Project, recommended offshore fill and armourstone revetment approximately 560 metres long from 33 – 85 Fishleigh Drive and 1 Midland Avenue to eliminate toe erosion and realize self-stabilization of the bluffs.  This Class EA was approved and construction commenced in 1988.

In 1994, TRCA suspended construction to reassess the potential impacts of the project on an important portion of the bluffs known as the “needles”.  W. F. Baird & Associates were retained to provide options for a termination point of the armourstone revetment structure.  They provided six options and weighted the capabilities of each to provide adequate erosion protection while preserving the needles feature.  A committee was established consisting of representatives from Metropolitan Toronto, City of Scarborough, Waterfront Regeneration Trust, local politicians and affected homeowners.  Collectively, it was decided to end the revetment structure below 83 Fishleigh Drive; 150 meters short of the 1988 approved length.  The motion was carried under the stipulation that “Authority staff investigate further options to ensure the long term safety and protection of Nos. 1 and 5 Midland Avenue and Nos. 81 and 83 Fishleigh Drive” (Water and Related Land Management Advisory Board, 1995).

Aerial photograph of existing erosion control
Figure 4: Existing erosion control. Source: TRCA, 2015.

Purpose

Since the approval of the original ESR in 1988 and the completion of the existing shoreline protection in 1995, the properties at 81 Fishleigh Drive, 83 Fishleigh Drive and municipal infrastructure at this location have been left vulnerable to powerful southeasterly waves resulting in toe erosion and subsequent crest recession.

The initial objective of this project was to implement remedial works along the face of the Bluffs and extend the existing shoreline protection to provide long-term protection to 81 and 83 Fishleigh Drive and municipal infrastructure along the road allowance of Fishleigh Drive and Midland Avenue.

An addendum to the 1988 Fishleigh Drive Erosion Control Project ESR was prepared to address the continued and unanticipated erosion concerns at the eastern extent of Fishleigh Drive while maintaining the natural formation of the bluffs directly east of the project area. This addendum was filed for public review and approved by the Ministry of Environment and Climate Change on April 07, 2016.

Following the rescheduling of construction to 2017, TRCA entered into negotiations with the homeowners of 83 Fishleigh Drive and successfully acquired the property. This acquisition negated the need for the remedial works along the face of the bluffs as the shoreline component was deemed sufficient to protect 81 Fishleigh Drive and the municipal infrastructure. This provided an additional opportunity to reconfigure the shoreline work to reduce the amount of material that would need to be placed in the water. This change will reduce the overall construction duration and minimize the environmental impact of the project.

Scope of Work – 2017

  • Site preparation
  • Stockpiling of material
  • Construction of revetment extension
  • Fish habitat creation
  • Site restoration
  • Fish habitat compensation monitoring

Duration

Construction is currently scheduled from May to December 2017, pending the receipt of necessary approvals, with habitat compensation and monitoring from 2017-2022. Please visit this section regularly for up-to-date schedule information.

Trail Closure

In the interests of public and worker safety, admittance to the TRCA access road running from Glen Everest Road (east of Wynnview Court and west of Fishleigh Drive) to the base of the bluffs will be restricted to construction staff and equipment for the duration of the project.

Map of trail closure
Figure 5: Trail closure. Source: TRCA, 2016.

Public Notices & Contact Information

The following Notices have been issued in the Scarborough Mirror and Bluff’s Monitor and have been distributed to Ward 36 Councillor Gary Crawford, residents in the vicinity of the work, and those who have expressed interest in the project.

A project sign will be erected at the entrance to the TRCA access road as well as at various locations close to the project site to advise those in the area of the construction activity.  The signs feature contact information so those interested can obtain further details regarding the project.

For more information on the Fishleigh Drive Erosion Control Project please contact:

Jet Taylor, Project Manager I
Toronto and Region Conservation Authority
Engineering Projects
Restoration and Infrastructure Division
Phone: 416.688.7627
Email: jtaylor@trca.on.ca

Reports

Progress Updates

This section will be updated prior to and during construction activities. Please check back regularly for progress updates.