Regents Slide 05-1R6404

Summary

SCH Number
2025010838
Public Agency
California Department of Transportation, District 5 (DOT)
Document Title
Regents Slide 05-1R6404
Document Type
NOE - Notice of Exemption
Received
Posted
1/27/2025
Document Description
A large landslide occurred on the evening of February 9, 2024, approximately ¼ mile south of the Big Creek Bridge on the Big Sur Coast. The landslide, Regent’s Slide, initiated approximately 450 feet above Highway 1, covering both lanes and closing the road. Over-steepened slopes on the margins of the landslide continue to fail, leading to rockfalls and debris slides that make the slide unsafe to cross. Removal of the undermined soil and rock mass from the top-down is the only feasible alternative to safely reopen Highway 1. Failure of both the soil and rock zones of the slide will continue to cause undermining and headward advance of the landslide into the relatively flat area above the current head-scarp limits. If left in the current condition, soil and rockslides will continue to fall onto Highway 1 and bury the roadway. The UAS model was used to develop preliminary estimates of the excavation limits and excavation volume. The estimated excavation volume at a stable backslope of 1¼:1 is approximately 750k-1.5 million cubic yards, to be verified with a survey and design of a roadway corridor and cut surface. Due to the convex nature of the ridge and slide, beginning the excavation in the right location and carrying the slope geometry down with slope staking will be critical. Due to the steep nature of the slopes above and below the roadway bench, capturing excavated material and trucking it offsite from the roadway elevation will not be possible. Material excavated from the top of the slide will be pushed to the edge of the bench and allowed to form a talus slope into the Pacific Ocean, as is already occurring with the natural processes of slope movement, erosion, and deposition. Note the rocky beach at the toe of Regent’s Slide, evidence of the natural depositional environment. To access the top of the slide, crew and equipment will use Whale Point Rd. To prepare the road for use, three areas will need to be stabilized with crush rock. The 750K to 1.5 million cubic yard estimate includes both the material on the roadway as well as the material to be removed from the slope.

Contact Information

Name
Jeremy Sheffield
Agency Name
Caltrans
Job Title
Environmental Coordinator
Contact Types
Lead/Public Agency

Location

Counties
Monterey
Regions
Northern California
State Highways
Highway 1
Other Location Info
District 05 Highway 1 MON Co PM 27.8

Notice of Exemption

Exempt Status
Statutory Exemption
Type, Section or Code
15269C
Reasons for Exemption
Emergency repair to a publicly owned highway facilities necessary to maintain service essential to the public health, safety or welfare.
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