Hat Creek Landslide, located on U.S. Highway 95 near the town of Pollock, Idaho, started moving on January 27, 1974. The slide closed U.S. Highway 95 and the toe impinged into the Little Salmon River. The slide was about 2,300 by 500 feet and involved about one million cubic yards of material. Investigation and analysis centered around four alternatives: complete removal, lower slide removal, upper slide removal, and stabilization of the upper slide with groundwater control. The stabilization of the upper slide by groundwater control was selected as the most cost-effective alternative. A construction dewatering system, consisting of 45 eductor well points, was installed to provide a stable trench excavation. A drain trench, 700+ feet long, was constructed across the head of the slide. The drain trench contained 6-inch perforated pipe and 10-inch collector drain pipe covered by 4-1/2 feet of filter material. The stabilization work was completed in November, 1977 and realignment of U.S. Highway 95 in the fall of 1978 for a total cost of $770,000. (Author)

  • Supplemental Notes:
    • Proceedings of the Eighteenth Annual Engineering Geology and Soils Engineering Symposium, held at the Red Lion Inn, Boise, Idaho.
  • Corporate Authors:

    Idaho Transportation Department

    3311 W State Street, P. O. Box 7129
    Boise, ID  United States  83707-1129

    University of Idaho, Moscow

    Department of Geology and Geological Engineering
    Moscow, ID  United States  83844-3025

    Boise State University

    Department of Geology and Geophysics
    Boise, ID  United States 

    Idaho State University, Pocatello

    Department of Geology
    Pocatello, ID  United States  83201

    Idaho State University, Pocatello

    Department of Geology
    Pocatello, ID  United States  83201
  • Authors:
    • Charboneau, R G
    • Kuenzli, J R
    • Ramage, J
  • Conference:
  • Publication Date: 1980-4

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 61-80

Subject/Index Terms

Filing Info

  • Accession Number: 00334059
  • Record Type: Publication
  • Created Date: Sep 16 1981 12:00AM