Big Bar landslide response information bulletin

April 3 2020

Ongoing onsite operations

This week, the “nature-like” fishway on the west side of the Big Bar landslide area was completed. This fishway is constructed of boulders that are approximately 2 metres in diameter, the positioning and spacing of which will allow fish to pass through the slide area at a range of flow levels.

To augment the “nature-like” fishway, work is now underway on infrastructure required for a future pneumatic fish pump. This system will help minimize delays to fish passage and reduce stress to fish from handling. The work includes both the development of a staging area downstream of the slide and the construction of a concrete block fish ladder to guide fish to a holding pool. The Province of British Columbia’s River Forecast Centre predicts low water levels over the coming days. Prime contractor Peter Kiewit Sons ULC is working to complete critical in-water work like the installation of concrete blocks during this window.

On March 29, a blast of a rock outcrop at the north end of the East Toe resulted in a noticeable improvement to the water flow. This blast also exposed additional rock, which was subsequently drilled and blasted.

Crews are working to reduce the grade of the overland access road to make the route to the slide area more accessible for trucks and the potential transport of fish, if needed.

Finally, the Big Bar Ferry will launch its service for the season on April 7. However, with the evolving COVID-19 situation, Kiewit continues to restrict site access that is not critical to the current project scope.

The March 24th issue of the Information Bulletin referenced a “mass of slide debris situated elsewhere in the river”. To clarify, this debris is part of the Big Bar landslide initially reported on June 23, 2019. This large volume of slide debris lies north of the narrow canyon in an area difficult to access for hydrographic surveying. Details of the mass were unknown until recently when work to better understand the condition of the river bottom was completed upstream. The volume of slide debris that entered the river means that not all the material obstructing fish passage can be reached before high water arrives. We are currently studying the narrow canyon to determine the best approach before work resumes this fall.

An aerial of the “nature-like” fishway, which was completed this week on the west side of the slide site. Click to enlarge.

Blasting of the north outcrop of the East Toe on March 29 2020. Click to enlarge.

Crews putting the final touches on the “nature-like” fishway, which was completed last week. Click to enlarge.