Landslide Technology
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 Old Hwy 224, Biscuit Rock Rockslide 

Estacada, Oregon
Rockslide Blocking an Access RoadRockslide Blocking an Access Road
The Faraday Hydroelectric Project on the Clackamas River has several hazards up slope of the facilities access road.  Several rock slope failures have occurred at a location known as Biscuit Rock.  An initial failure involved two 6-foot boulders and was associated with a period of intense rainfall. As they fell, the rocks struck and up-rooted several trees near the top of the road cut.  The source of the rockfall was a tall basalt outcrop located about 100 feet above the road.  Several large blocks from previous events were observed at the base of the outcrop and coupled with the recent event were strong indicators that the future stability of the outcrop should be a concern.

Following this event, Landslide Technology (LT) was authorized to inventory the slopes along the length of the road. LT's RHRS rankings indicated that this slope was one of the more hazardous on the roadway.

A second event occurred following another heavy rainfall event, where the entire slope failed.  The failure was approximately 125 feet long, 90 feet wide, and had a volume of over 4,000 cubic yards. The rock blocks came from the columnar basalt referred to locally as the biscuit rocks and the upper more massive basalt outcrop.  Blocks up to 15 feet in size were measured.  Several smaller boulders reached the fish ladder located downslope of the road but did not cause any damage. 

Due to the unstable nature of the upslope area and because slide debris completely covered the road, PGE elected to close the road and wait for better weather conditions before cleanup and mitigation measures were implemented.  Prior to mitigation work, survey hubs, crackmeters, and extensometers anchor points were installed to monitor any slope movements during construction.  Mitigation included  removal of slide debris, reshaping of the lower portion of the slope, and construction of a free standing gabion wire wall (9 ft. tall by 10.5 ft. wide by 144 ft. long) on the inboard lane to provide containment and storage capacity for future rockfall and landslide events.


Services Provided:

  • Rock Slope Investigations
  • Rock Slope Hazard Assessment
  • Rockfall Mitigation
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  • Rock Slope Instrumentation
  • Emergency Response and Fast-tracked Mitigation Design
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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