March 3rd, 2017
The 400-metre-long tension crack on the north bank of the Site C dam site remains stable.
BC Hydro's design team and technical experts in slope stability have undertaken ongoing geotechnical assessments. Monitoring instruments, including survey prisms and inclinometers, show that the slope around the crack is stable. In addition, a drill rig has been mobilized to drill and install additional instruments to gain a more detailed understanding of the crack and our experts are currently examining the data.
Safety is our top priority. This work needs to be done carefully and no construction activities are taking place in the area of the tension crack until a plan is in place to safely remove the material while maintaining slope stability.
BC Hydro is developing a two-stage remediation plan. The first stage would include the construction of a toe berm to hold the area stable and this work could start within a few days. The second stage of the remediation plan would focus on allowing resumption of work on the north bank.
BC Hydro expects to complete the remediation work for the tension crack within the overall project budget and schedule.
As part of Site C construction, work has been underway for the past 19 months to remove unstable soil to create stable slopes for eventual dam construction. During the construction of a haul road to support this excavation work, a tension crack appeared. Tension cracks are not unexpected in this area; however, this particular crack requires attention due to its significant 400-metre length.
While there was some initial movement of soil, it has now stabilized. This area of unstable soil was already slated to be removed as part of engineering new stable banks for dam construction.