Landslide Technology
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    • Tom Westover
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Three Capes Scenic Loop Landslide

Tillamook County, Oregon
A landslide severed the Three Capes Scenic Loop Highway in Tillamook County, Oregon, on January 29, 1999 resulting in a 25-mile inland detour. Landslide Technology was retained by Oregon Department of Transportation to investigate and evaluate stability for emergency bypass. Permanent mitigation was also needed to restore the county road.

Objectives for remediation included: emergency access across the slide for summer; high winter groundwater and difficulties for earthmoving equipment; rapid beach erosion threatening to undermine the slide; limited uphill right-of-way; and aesthetic constraints of a State Park.

Landslide Technology investigated the slide with reconnaissance, borings and instruments, and developed a remedial solution combining groundwater dewatering with a rockfill shear key to buttress the landslide. The first stage was performed immediately to establish the emergency bypass, and involved horizontal drains to lower groundwater. This also allowed for safety during the second stage deep excavation and rockfill shear key. Discharging groundwater through a trench drain beneath the beach sand, and covering the rockfill with soil and re-vegetation maintained the scenic area.

Services Provided:

  • Emergency response assessments
  • Geologic reconnaissance of landslide areas
  • Site investigation by borings
  • Slope stability analyses
  • Evaluation of appropriate remedial options
  • ​Final design of selected remedial measures
  • Dewatering system designs
  • Buttresses and shear key systems
  • Technical assistance to owner during construction

Tillamook County wrote:  ​"Landslide Technology engineers were among the first people on-site [and] were critical players. "Communications between Consultants, lead contractor, and the County were excellent. The County was able to furnish the best information possible to the public… [The team] did an excellent job of coordinating and resolving issues unique to a project in a rural county."
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  • Home
  • Specialty Services
    • Geotech. Asset Mgmt. >
      • Montana Rock Slope Asset Mgmt. Program (RAMP)
      • Alaska Geotech Asset Mgmt
      • Ohio Landslide Inventory
    • Rope Access
    • 3D Modeling
    • Dam Safety & Slope Stability
    • Const. Sequence Modeling
    • Geotechnical Instrumentation
    • Construction Engineering
    • Expert Witness
  • Landslides
    • Hydropower >
      • Bull Run Flume
      • Swift Powerhouse
      • Frog Lake Dam Slide
    • Transportation >
      • Hwy 101 Johnson Creek
      • Looking Glass Hill Slides
      • SR 87 Arizona Slide
      • Togwotee Pass Road
      • Scoby Hill Landslide
      • Wrangell Airport
      • Snowbasin Access Road
      • Beartooth Debris Flows
      • Three Capes Scenic Loop Landslide
      • Richardson Hwy Slide
      • Bonners Ferry Landslide
      • Light Rail Station
      • Skagway Submarine Slide
    • Natural Resources >
      • West Africa Gas Pipeline
      • Greens Creek Mine Road
    • Private Clients >
      • Wasco County Landfill Landslide
  • Rock Slopes
    • Hydropower >
      • Biscuit Rock Rockslide
      • Skagit River Rockfall
      • JC Boyle Canal Rockfall
      • Prospect Dam Rockfall
      • Iron Gate Dam Rockfall
      • Cougar Dam Rockfall
    • Transportation >
      • I-15 (D3) Rock Slope Mitigation
      • Ketchikan Third Avenue
      • US Hwy 2 Libby Rockfall
      • Banks - Lowman Hwy
      • SR 191 Rock Cut Design
      • Going-to-the-Sun Road
      • SR 12 Rockfall Mitigation
      • Lakeside Rockfall
      • US 2 Badrock Canyon
      • South Tongass Highway
      • Weeksville Rock Bolting
      • US 26 Cove Palisades
  • Key Staff
    • Mike Meyer
    • Gerry Heslin
    • George Machan
    • Charlie Hammond
    • Brent Black
    • Darren Beckstrand
    • Chris Carpenter
    • Ben George
    • Wade Osborne
    • Tom Westover
    • Aine Mines
    • Adam Koslofsky
    • Logan Allender
    • Andy Kost
    • Collin McCormick
    • Anna Casady
    • Noah Kimmes
    • David LaPorte
    • Justin McCarley
    • Aleyna Donaldson
    • Michael Bunn
    • Andy Vessely
    • Larry Pierson
    • Derek Cornforth (Founder)
  • Resources
  • Contact Us