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Slope stability an issue to certain areas of Waterways

Last Updated Mar 7, 2017 at 7:22 pm MDT

A heavily damaged area of the community of Waterways pictured on June 8, 2016.

A slope stability assessment for Waterways is showing that not all areas of the neighbourhood may be redeveloped.

A Here For You session was held on March 7 to present the information to residents.

On Sept 27, 2016 Council approved a motion to complete an overall geotechnical assessment of the Waterways area. Thurber Engineering performed the assessment to look at general slope stability and their report identifies different areas of Waterways will face different factors, considerations, risks and issues when it comes to rebuilding.

Four zones were outlined in the report.

 

Zone 1 — Blue Area: Rebuilding can continue, following the Municipality’s standard guidelines.

Zone 2 — Beige Area: Suitable for redevelopment, however property owners will have to submit a site specific geotechnical report at the time of the development permit.

Zone 3 — Yellow Area: Rebuild can continue as long as careful planning, construction and maintenance are followed. Site specific geotechnical investigations will be required.

There will be special provisions for rebuilding such as, no additional excavations will be allowed into the slope, like creating more space in a backyard for another building or a bigger house.

Finished grades should not be changed by more than 0.5 metres of the current grades. No swimming pools, decorative ponds and in-ground sprinkler systems will be allowed in the area. No stockpiling of materials on the slope.

Zone 3A — Red Area: The zone that is most at risk to slope stability. Ground movement can affect redevelopment if stabilizing measures are not taken. Rebuilding for this zone will not be allowed until a decision is made by Council.

The Recovery Task Force has looked at three mitigation options for zone 3A.

Warn and restrict: This option would require residents to submit a geotechnical report at the time of the development permit. All special provisions for zone 3 would apply for zone 3A. Additionally there could be no uncontrolled excavations, foundations must have the foundation walls designed as structural retaining walls capable of supporting soil behind them. This option would only slow the rebuild for as long as the resident takes to complete the geotechnical study.

Structural mitigation: Municipality would be required to complete a comprehensive geotechnical study. Depending on the findings of the study the RMWB could build a series of retaining walls. The retaining wall that is along Cliff Avenue from Tomlinson Street to Huggard Street would be expanded and improved.

This option could delay residents up to a year in the rebuild process and cost the Municipality close to $8 million.

Acquire, no development, mitigate: If the municipality was to acquire the land it would be rezoned to restrict development. Not rebuilding in this area would decrease the overall risk to zones one (blue area) and three (yellow area). This option would give residents in zone 3A immediate certainty. A cost for this option is not available as each lot would require a site specific appraisal to determine its value.

The Recovery Task Force will present the finding of the report to the Wood Buffalo Recovery Committee (WBRC) on March 8 and the WBRC will be responsible for making the recommendation to council. The geotechnical assessment will be posted on the municipality’s website on March 10.