Cornforth Consultants
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      • Montana Rockfall Hazard Rating System
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      • OTIA Cracked Bridge Geotechnical Baselines
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      • Navy CVN Drydock
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      • Fern Hill Water Treatment Plant
      • Tualatin Valley North Transmission Line
      • Evaluation of 28 Water Storage Facilities
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      • Mt. Tabor Reservoir No. 5 Cap Study
      • Oakridge Water System Improvements
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U.S. Highway 2 Rockfall Mitigation

Libby, Montana
A wedge failure developed in a new rock cut slope along U.S. Highway 2 west of Libby soon after it was constructed in 1992. By 2005, the wedge failure had retrogressed beyond the crest of the original cut slope to form a trough, extending approximately 130 feet into the slope that was over 150 feet wide and nearly 200 feet high. Due to the slope height, continuing rockfall activity, concerns for worker and traffic safety, and a history of vehicle involvement; MDT retained Cornforth Consultants through its division, Landslide Technology (LT), to develop mitigation measures to reduce rockfall hazards. Tasks included detailed geologic and rock structural mapping, rockmass characterization, stability analyses, computer rockfall simulations, and development of rockfall mitigation measures.

​Mitigation measures included: scaling, shotcreting, rock bolts, draped ring nets, and a rockfall barrier fence. Final design plans and special provisions were developed for MDT to include in bid package documents. Following the bid letting, LT provided continuous technical support during construction activities.
Drill Rig Buried by Rockfall
Excavation of Fallen Rock in Wedge Failure

​Services Provided:

  • Earthquake Hazards
  • Rockfall Hazard Rating System (RHRS)
  • Debris Flow Hazards & Mitigation
  • Probabilistic and Deterministic Risk Analysis
  • Geotechnical Prioritization Systems
  • Landslide Hazard & Susceptibility Assessment
  • Volcanic Hazards
  • Geotechnical Asset Management
  • Geomorphic Mapping
  • Expansive/Collapsible Soils
  • Home
  • Services
    • Earth & Rockfill Dams
    • Reservoirs, Canals, and Levees
    • Spillway Safety Inspections
    • Landslides and Rockfall
    • Earthquake Engineering
    • Geologic Hazards
    • Geotechnical Site Characterization
    • Hydrogeology
    • Expert Witness
    • Concrete Dams and Locks
    • Geotechnical Instrumentation
    • Deep and Shallow Foundations
    • Geotechnical Manuals
  • Industries
    • Water Resources
    • Energy
    • Natural Resources
    • Industrial
    • Transportation
    • Ports and Airports
    • Expert Witness
  • Projects
    • Earth and Rockfill Dams >
      • Barney Reservoir
      • Frog Lake Reservoir
      • Iron Gate Dam Raise
      • McGuire Dam Raise
      • Bonneville Cofferdam
      • Bull Run No. 2 Seismic Stability Analysis
    • Levees and Canals >
      • Libby Dike Rehab.
      • St. Johns Dike Stabilization
      • Cowlitz River Levees
      • Swift Canal Failure
    • Earthquake Engineering >
      • Barney Dam Seismic Analysis
      • Fern Hill WTP Liquefacation Study
      • Bull Run No. 2 Seismic Stability Analysis
      • Mt. Tabor Seismic Stability Analysis
      • Port Westward Power Plant Seismic Design
    • Rock Slopes and Tunnels >
      • Libby Rockfall Mitigation
      • Sandy River Pipeline Tunnels
      • Ketchikan Third Avenue Extension
      • Sain Creek Water Supply Tunnel
      • Montana Rockfall Hazard Rating System
    • Foundations >
      • Port Westward Power Plant
      • Cascade Locks Casino
      • Air National Guard Hangar
      • Biglow Canyon Windfarm
      • Oakridge Water System Improvements
    • Concrete Dams and Locks >
      • John Day Lock & Dam
      • Marmot Dam Removal
      • The Dalles Dam
      • Willamette Falls Dam
      • Bonneville Dam
    • Transportation >
      • OTIA Cracked Bridge Geotechnical Baselines
      • Newburg Dundee Bypass Design DEIS
      • I-84 Sandy River Bridge Investigation
      • Tanana River Bridge Foundation, Tok, Alaska
      • Montana RHRS Implementation
      • Ketchikan Third Avenue Extension
    • Ports and Airports >
      • Navy CVN Drydock
      • Depoe Bay Seawall Distress
      • Willamette Falls Flow Control Structure
      • Air National Guard Hangar
    • Water and Wastewater >
      • Fern Hill Water Treatment Plant
      • Tualatin Valley North Transmission Line
      • Evaluation of 28 Water Storage Facilities
      • City of Sandy Water Treatment Plant
      • Mt. Tabor Reservoir No. 5 Cap Study
      • Oakridge Water System Improvements
  • Staff
  • Resources
  • Careers
    • Geotechnical Engineer
  • Contact Us