Emergency causation analysis and remedial measures

Seismic resistance evaluation of new bridge foundations

In late November 1995, torrential rainfall caused a landslide on the south bank of the Bull Run River just downstream from Bull Run Dam No. 2. The landslide destroyed a bridge foundation supporting two conduits that supply most of the drinking water for the city of Portland.

Landslide Technology was retained by the Portland Water Bureau to perform an emergency evaluation of the slide area. Within days, Landslide Technology had reviewed the failure, performed a geologic reconnaissance, developed a plan for mitigation, and assisted the Water Bureau bridge and pipeline consultants with siting the new bridge foundation. The firm also performed a calculation of lateral resistance of bridge foundations to earthquake forces.