With work on ground anchor installation at the east abutment now underway, this week’s update focuses on the bigger picture of the Pretty Rocks area and the ongoing movement of the landslide that set the entire project in motion (pun intended).
This timelapse covers the period from June 17th to July 29th . Courtesy of BGC Engineering/FHWA
This timelapse covers the period from June 17th to July 29th of 2024. As the former park geologist Denny Capps says, we’ve entered the time of year where the landslide reaches maximum velocity. This is the result of the long, warm days melting the ice-rich permafrost in the body of the landslide, destabilizing it. Once the permafrost is destabilized, gravity does the work of moving the destabilized material downhill, as evidenced by the movement shown in the timelapse. The contractor performs weekly surveys tracking overall movement within the landslide as well as monitoring survey prisms installed at selected locations, including points at, below, or above both abutments, and several points within the body of the slide. During the time period shown in the timelapse, the prisms within the slide have moved at an increasing rate, which is currently approaching three feet per week. The stable rock surrounding the abutments, meanwhile, has not moved since monitoring began.