Shale Point RSP Revetment 05-1R190 MON-001-7.2/7.9

Large swells and high tides hit the Central Coast during the week of December 24th, 2023. Wave erosion from the high seas damaged slopes supporting Highway 1 along the Big Sur Coast, causing significant damage to existing rock slope protection (RSP) revetments and gabion wall shoreline protection at Shale Point, located between Ragged Point and Gorda. In addition, Mud Creek Landslide loss approximately 6 tons of rock protection. The shoreline north and south of Shale Point is armored from the Pacific Ocean with RSP designed to prevent wave action from eroding the slopes that support Highway 1. Two gabion basket walls at the north end of the northern beach also provide armoring along with naturally occurring rock that accumulates along the northern shoreline. The combined high tides and very large waves in late 2023 evacuated RSP from the revetments and caused rotation of the South Gabion Wall, allowing wave runup and splash to scour and undermine the now unprotected slopes. Evidence of slope failures advancing toward the Highway is apparent and worsening as continued winter swells and high tides persist into January 2024. Mud Creek Landslide revetment experienced large wave events and hightides at the end of 2023, which caused damage to several areas where wave energy concentrates, again requiring replenishment of evacuated rock. Protection of the slopes by re-armoring the toe at the ocean elevation is required to prevent slope retreat into the roadway prism. Replacement of the evacuated RSP at Mud Creek and at Shale Point South and North Revetments, including armoring the failed South Gabion Wall with RSP were recommended to halt the current damage and protect the Highway from continued slope failures caused by wave action.