Caltrans Last Chance Grade

Gregg Drilling has completed a $1.5M project for Caltrans working with Kleinfelder on the Last Chance Grade near Eureka, California. For the past 40-years a slow-moving landslide along US Highway 101 in Del Norte County has caused numerous failures and required patch repairs to the highway. The Last Chance Grade Project is a collaborative effort to study alternatives for a permanent solution to instability and roadway failure on this segment of US Highway 101. Alternatives include a tunnel bypass or end-to-end re-engineering of the highway. Gregg has conducted numerous sonic and mud rotary boreholes, well installations and instrumentation installations to further investigate the current landslide and possible alternatives.


  • 20 boreholes, including vertical and angled, 100-200ft bgs
  • Inclinometer and piezometer installations
  • 4″ well installations for groundwater monitoring
  • Packer testing
  • Contract value $1.5M

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