MALIBU—The city of Malibu indicated on its website that Caltrans is holding a virtual community meeting about the PCH Big Rock Retaining Wall Project on Thursday, November 18 at 6 p.m. Community members are invited to attend, learn about the project and ask questions.
Caltrans is planning a permanent slope restoration on Pacific Coast Highway in Malibu. Construction of the $12.4 million project just south (east) of Big Rock Drive is scheduled from September 2022 through July 2023. Utility relocation will transpire from September 2021 through October 2022. The work zone spans 180 feet on southbound PCH, which will require shifting lanes toward the hillside to make room for special construction equipment.
Storm damage during the winter of 2015-2016 caused slide damage along the slope, endangering the shoulder and the right southbound lane of PCH. Caltrans examined the risk to the stability of the roadway and issued a Director’ s Order on June 10, 2016 for an emergency project to apply short-term protective measures to the collapsing slope and shoulder. The project installed a “shotcrete” wall as a temporary fix, but is being undermined by sea waves, endangering the southbound shoulder and southbound right lane.
To ensure space for construction along the 180-foot stretch of shoulder and roadway, traffic lanes will be shifted toward the hill, with the 10-foot-wide median reduced to 2 feet. There will be three 10-foot-wide lanes and one 11-foot-wide lane during construction, with no shoulder in both directions. The speed limit in the work zone will be reduced to 25 MPH. There will be no pedestrian access in construction area. Bicyclists are allowed to share right highway lanes.
The 180-foot beach area is susceptible to erosion and needs slope protection permanent slope restoration must be completed as soon as possible to prevent erosion, flooding and enlargement of sinkholes that may trigger long-term closures of State Route 1 (Pacific Coast Highway/PCH), an essential route for residents, commuters, emergency services and commercial traffic.
A secant pile wall will permanently restore the slope, 600 linear feet of widened shoulders and 178 linear feet of concrete barrier. The new wall also will dissipate the energy generated by the waves.
Cast in Drilled Holes (CIDH) are high-capacity cast-in-place deep foundation elements constructed using an auger to drill a hole, in which steel reinforcement and concrete are placed. Secant pile walls consist of overlapping CIDH piles, creating a water-tight surface. Two types of piles are used in secant pile wall construction, a “primary” or reinforced pile, and a “secondary” or unreinforced pile. Primary and secondary piles alternate, to create a wall of piles. The main advantages of Secant Pile Walls are: Increased construction alignment flexibility, increased wall stiffness compared to sheet piles, can be installed in difficult ground (cobbles/boulders), less noisy construction.
To learn more details about the project visit https://dot.ca.gov/caltrans-near-me/district-7/district-7-projects/d7-sr1-slope-restoration. For questions about the project email Public Information Officer, Jim Medina of Caltrans District 7 at james.medina@dot.ca.gov. General work hours are expected Monday-Friday from 6 a.m. through 9 p.m. Weekend work is permitted.
