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Erosion Management Program

 The prevention, elimination or reduction of risk to life and property from flooding and erosion is one of the core mandates of the Toronto and Region Conservation Authority (TRCA). TRCA's Erosion Management Program seeks to fulfill this mandate through the ongoing identification and remediation of erosion hazards, carried out on a priority basis and subject to available funding.

Picture of erosion threating adjacent property and roadway

Background

The Conservation Authorities Act is provincial legislation that was created in 1946 in response to flooding and erosion concerns and the recognition that these natural hazards are best managed on a watershed basis. This Act is the basis for TRCA's mandate to prevent, eliminate or reduce the risk to life and property from flooding and erosion, and to encourage the protection and regeneration of natural systems.

The Conservation Authorities Act gives Conservation Authorities the power to establish and undertake programs that help achieve its objectives, from developing watershed plans, to policies that guide the review of development applications, to various programs ranging from education and stewardship to the implementation of restoration activities. With respect to erosion control and remediation, TRCA has a long-standing management program to monitor erosion and instability-prone areas, and to implement stabilization works on a priority basis to the limit of available funding each year. This program is funded annually by TRCA's partners at the City of Toronto, Peel Region, York Region and Durham Region, and on a project-by-project basis by the Ministry of Natural Resources.

Scope of Program

The majority of funding is applied toward the maintenance of existing erosion control structures (e.g. retaining walls, revetments) along TRCA's rivers and valleys that protect public greenspace, park amenities and municipal infrastructure, however this program is extended to the protection of private property in extreme cases where homes and other essential structures have been confirmed as at-risk by erosion or instability.

To determine where available funding is recommended to be allocated each year, TRCA monitors its existing erosion control structures and known erosion hazard sites on both public and private property, and assigns a priority ranking for maintenance or remedial works. Monitoring is carried out year-round in response to public inquiries or following severe weather, however scheduled monitoring is typically carried out between May and September each year to establish a list of capital projects for the following capital year and forecasted works for the next 5 or 10 years, this forecast being updated at least annually based on changing priorities as a result of a change in site conditions or new sites being identified (e.g., as a result of storm damage). It is noted that all erosion control work is also subject all necessary municipal, provincial and federal approvals before being implemented.

July 8, 2013 Severe Weather Event

In the early evening hours of July 8, 2013 a severe thunderstorm rolled through the Toronto area, bringing large amounts of rainfall to the west end and downtown areas of the city over the span of a few hours. This intense downpour of precipitation not only resulted in extensive flooding of major roadways and transit infrastructure, but also caused significant damage to our river and valley systems, the park amenities found within them, the water infrastructure buried beneath them, and many of the older neighbourhoods that border them.

Beginning the morning of July 9th, TRCA began receiving calls and emails from landowners, park users and municipal staff about various types of damage sustained during the storm event. These reports ranged from minor damage to asphalt park paths, to debris jams, to major "landslides" and backyards "collapsing". Calls were vetted  through senior Restoration Services staff and prioritized for inspection based on information at hand, then added to a storm damage inventory list before inspectors were dispatched to complete preliminary assessments.  Staff also prioritized a list of inspections of previously known erosion hazard sites and at-risk erosion control structures which already ranked high on the priority list.

Recognizing that TRCA has considerable experience and the necessary tools and protocols in place to assess and track erosion and slope instability hazards through its existing Erosion Management Program, the City of Toronto - which was also receiving an influx of calls following the severe weather event - has since referred all erosion-related reports to TRCA for preliminary inspection and addition to the damage inventory. This cross-organizational cooperation has allowed staff to respond to the public's concerns in a timely fashion and disseminate information to the appropriate departments following initial inspection, while building and maintaining a jurisdiction-wide database of erosion damage from the July 8th event. TRCA is currently in the process of contacting its other municipal partners and inspecting areas in Peel, York and Durham to inventory storm damage in these areas and add the information to TRCA's inventory database.

By July 12th TRCA had completed more than 140 scheduled inspections, with 27 properties flagged as "critical" or "high" priority  for further inspection. On July 16th TRCA retained Terraprobe Inc. on an emergency basis to complete a preliminary assessment of slope stability and erosion risk at these priority areas, which included visual inspection, slope mapping and rating,  photographs, and an assessment of potential causes, stabilization options and ballpark repair costs. The results of this assessment were provided in a report to TRCA on July 25th, which recommended that these priority areas undergo a detailed geotechnical assessment.

Reports of damage continued to be received into August, growing the list to more than 300 sites as TRCA inspected additional areas in Mississauga, Brampton and other areas in its jurisdiction. 

Updates

 Updates on TRCA's erosion hazard response and remediation efforts following the July 8th event will be posted below as more information becomes available. 

July 30, 2013:

TRCA is currently in the process of preparing a Terms of Reference to retain a consulting geotechnical engineer firm to complete detailed investigations at the priority areas confirmed by Terraprobe Inc. in their July 25th report.

It is anticipated that the detailed investigation process will commence the week of August 26th pending the receipt of the necessary approvals and confirmation of available funding, and will take approximately eight (8) weeks to complete. The results of this investigation will be used to determine whether stabilization works are required, potential options and preliminary costs for these works.

It is noted that all work is carried out on a priority basis and subject to available funding. Given the extent of damage from the July 8th event far exceeds TRCA's annual funding to remediate erosion hazards, additional funding will be needed to address new hazards that have been identified.  On July 26th staff were directed by the Authority Board to approach TRCA's funding partners with a request for enhanced funding in 2013 and 2014+ to address priority areas.

In light of the extent of damage already inspected and the continued receipt of new reports daily, the process of assessing and prioritizing potential future repairs will be lengthy, however TRCA remains committed to fulfilling its mandate to protect life and property from the hazards of erosion to the best of its ability. Your continued patience is appreciated as this important information-gathering and assessment phase is completed.

July 31, 2013:

A link to TRCA's report to the Authority on July 26th, 2013 regarding erosion management  for the July 8th severe weather event is available here:

 http://www.trca.on.ca/dotAsset/164086.pdf

August 2, 2013:

TRCA is continuing to receive reports of erosion damage sustained during the July 8th event, with more than 260 erosion hazard inspections completed since July 9th (98% of reported sites).

August 21, 2013:

  • TRCA has inspected more than 350 sites to date
  • A second round of preliminary slope stability and erosion risk assessments has been requested for additional priority sites identified after July 12th
  • TRCA inspectors are continuing their search for additional damage in the City of Mississauga

September 3, 2013:

TRCA received three proposals for the detailed geotechnical investigations of priority areas identified in Terraprobe's July 25th report on August 21st as expected, however due to a wide range in pricing, staff requested additional information to aid in determining which firm to recommend the contract be awarded to. 

Staff are currently reviewing the additional information provided and expect to make a recommendation this week. Updated timelines for the study will be posted once the recommended firm has been determined. 

September 27, 2013:

TRCA has set up a Storm Damage Management Portal for properties that were damaged by erosion during the July 8, 2013 event and have already been inspected by TRCA. Please visit http://trca.on.ca/stormdamageinfo to register your property to view customized information for your area.

If your property has not been inspected by TRCA but was damaged by erosion during this event, please call (416) 392-9676 to schedule an inspection.

Contact Information

For more information or to arrange an inspection please contact erosionmonitoring@trca.on.ca or call (416) 392-9676.

Reference Materials

What you Should Know as a Ravine or Bluff Property Owner PDF

Ravine and Natural Feature Protection By-Law PDF