North Fork Road “Bear Trap” Landslide, Marion County, Oregon


GeoDesign provided geotechnical and geological services for evaluating and remediating the Bear Trap landslide, which affected a major County arterial.

Our services included:

  • emergency response, including recommendations on lane restrictions and temporary mitigation work
  • a geotechnical investigation to characterize landslide conditions
  • development of slide mitigation approaches

We designed a retaining wall that supported the roadway, but as that proved to be cost prohibitive, we alternatively recommended constructing the wall downslope of the current road alignment. This allowed a shorter and less expensive wall design than would have been required to maintain the existing alignment.

Construction was completed in September 2011, and the road reopened to all traffic before the start of the rainy season.


  • The County estimated that our recommendation for roadway realignment and wall modifications decreased the cost of the project by approximately $700,000.
  • Our services helped ensure traffic would be able to reach the popular resort area serviced by the affected road.


Geotechnical consulting, geological consulting, subsurface investigation, landslide characterization & remediation, retaining wall design