Invermere - Toby Creek Dike Improvements

pre-construction

Invermere has experienced flooding and ice jam events in the areas adjacent to Toby Creek. Invermere has completed the Toby Creek Flood Risk Assessment and Mapping to update Toby Creek flood maps and risk assessment: the hydraulic model suggested the climate adjusted 1:200-year flows are mostly contained within the existing dike structure with the exception of a few reaches where water levels are expected to reach and overtop the dike structure. There is no freeboard along the dike system. Following EGBC guidelines, the freeboard elevation should be the climate adjusted 200-year water surface elevation plus 0.6m. With this project Invermere intends to raise the dike elevations along Toby Creek to the climate adjusted 1:200-year flows plus 0.6m of freeboard. There are four locations where the dike elevations need to be raised to contain the climate adjusted 1:200-year flows: the north end of the dike where the dike meets Panorama Drive, two areas in the middle of the structure alignment, and location at the furthest south part of the dike. Improving the dike elevation at the south end will help mitigate against potential ice jam conditions as that is where flows have overtopped the dike previously. With this project the dike system will also be provided with the provincially required 0.6m of freeboard. The project consists of raising the dike systems along Toby Creek including: - Approx. 300m North End dike raising to climate adjusted 1:200-year flows plus 0.6m of freeboard. - Approx. 100m South End dike raising to climate adjusted 1:200-year flows plus 0.6m of freeboard. - Approx. 50m Central dike raising to climate adjusted 1:200-year flows plus 0.6m of freeboard. - Approx. 600m dike raising to the 0.6m freeboard. - Approx. 120m perimeter berm construction. - reconstruction of the existing trail on top of the dike. - vegetation restoration. It is expected that the dike raising would mostly consist of placing imported rip rap on top of the existing structure.