Coastal Commission approves plans to repair slope next to UCSD

A map shows a slope failure (in the red box) in La Jolla.
A map shows a slope failure (in the red box) in relation to the National Oceanic and Atmospheric Administration Southwest Fisheries Science Center in La Jolla.
(Courtesy of UC San Diego)

A 4-year-old slope failure in La Jolla is a step closer to being fixed after the California Coastal Commission voted unanimously Sept. 7 to approve a coastal development permit to repair and revegetate the slope.

According to a staff report associated with the project, the work will include fixing a slope failure caused by a water line break in 2018 southwest of La Jolla Shores Drive next to UC San Diego’s Scripps Institution of Oceanography campus. The affected slope area is about 100 feet long and 75 feet wide. The site is bounded by the National Oceanic and Atmospheric Administration Southwest Fisheries Science Center to the northwest, the Keck Center building to the southwest, La Jolla Shores Drive to the north and east, and vegetated areas to the south and east.

The project includes the failed slope itself as well as areas for soil compaction and construction staging, according to the report.

UCSD spokeswoman Laura Margoni told the La Jolla Light that work is slated to begin in early 2023 and take about six months to complete.

The total project site is about 12,000 square feet, including the 5,000 square feet of the failed slope.

“Although the existing slope currently consists of sandbags and plastic tarps to prevent further saturation and erosion, the slope was previously covered in natural vegetation prior to the slope failure, during which most of the vegetation was washed away,” the report states.

An estimated 350 square feet of coastal sage scrub was impacted by the failure, and an additional 4,800 square feet of scrub will be impacted by activities necessary to recontour the slope, according to the report.

The project was listed on the Coastal Commission’s consent agenda and therefore was approved without presentation or discussion.

However, the approval came with five special conditions:

• That final plans use the construction methods and staging and access areas that were previously reviewed by commission staff

• That heavy-duty plastic netting be prohibited for sediment and erosion control in order to avoid or reduce the threat of wildlife entanglement

• That the applicant submit final landscaping plans

• That a survey of nesting birds be done at appropriate times of the year, with noise-reducing measures implemented in case noise levels at a nesting site become too high

• That the applicant adhere to a cultural-resources treatment and monitoring plan

According to the report, the slope failure occurred because of a broken 4-inch irrigation line along the top of the slope.

“Following the failure of the water main, water was discharged onto the adjacent slope, which caused it to become saturated,” the report states. “Several open fissures and side scarps (or ditches) that are about 3 to 4 feet deep were observed shortly after the failure. Several tunnels were also observed within the upper and middle portions of the slide mass and were measured to be approximately 6 to 12 inches in diameter and 12 to 18 inches deep.

“The main side of the scarp along the north side of the slope failure appears to have captured a significant amount of surface water flow, which has deepened and widened the fissure into a large gulley that is up to 4 feet wide and 3 to 4 feet deep.” ◆