Mountain View Boulevard, which connects the city of Billings, Montana to the Billings Logan International Airport, (Mountain View does not connect the City to Logan that is Ridge Road) sits underneath a sandstone cliff overlooking the city. This past June, a boulder estimated to weigh over 50 tons fell from the cliff and rolled past Mountain View Boulevard where it subsequently damaged a residence and destroyed a vehicle. GeoStabilization’s Rockfall Remediation Technicians (RRTs) were dispatched to assess the scene and prepare (although we were there to help validate the solution it was Terracon that did the design) a solution to prevent similar rockfall events from reoccurring along the rim.
Working closely with geologists from Terracon, the team developed a solution to bring down the remaining unstable material threatening the structures below. Because of the proximity of houses below the rim, blasting the material out was not feasible. The team instead chose to scale the material with pneumatic lifting bags in a controlled manner. Before the work began, GeoStabilization’s engineers inquired about possible underground utilities and learned that a gas line was buried beneath the road. To protect this (It should be “the” because the berm was in there predominantly to protect the houses below) infrastructure, an earthen berm was constructed to contain falling material and limit the run out during the scaling process.
GeoStabilization’s RRTs began their work by removing a 200-ton rock slab perched precariously on the rim. They then removed smaller boulders along the slope face. The project was a success; the earthen berm successfully contained the material and protected the underground utility, and none of the rocks removed will ever be able to threaten the lives and infrastructure along Mountain View Boulevard again.
To learn more about the project, click here.
Swinging Bridge Anchors, Virginia Department of Transportation