Challenges Faced During the Emergency Response to the Bear River Canal Failure

A landslide caused failure of a section of PG&E’s Bear River Canal near Colfax, California. The canal failure disrupted a major source of water for western Placer County, affecting thousands of residents. Pacific Gas & Electric retained Sanders & Associates Geostructural Engineering, Inc. to evaluate the landslide failure and perform expedited engineering design to repair the failed canal on an accelerated schedule. The failure occurred on very steep slopes in a remote area with limited equipment access. The emergency response required the development of a unique engineering design to rapidly repair the canal in this potentially dangerous terrain. The selected repair method consisted of placing approximately 2,000 cubic yards of unreinforced cementitious fill to replace the slope materials lost in the failure. This created a stable subgrade for a new at-grade reinforced concrete flume section, while reducing the need for personnel or equipment within the potentially unstable failure zone. Global stability for the fill mass was achieved using a reinforced concrete waler and five multi-strand tieback anchors post-tensioned to 350 kips each. The anchors were installed concurrently with the flume construction using limited-access drilling equipment winched down the slope face. Engineering and construction of the repair were substantially completed in just over six weeks and 10 days ahead of schedule, allowing full canal operation and delivery of water supply. This paper shares experiences from the geological and geotechnical investigation, the alternatives evaluation and selection, the engineering design process, the construction process, and lessons learned from this fast-track project.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 378-394
  • Monograph Title: Proceedings of the 63rd Annual Highway Geology Symposium (HGS 2012)

Subject/Index Terms

Filing Info

  • Accession Number: 01661555
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 25 2018 11:48PM