The California Coastal Commission recently approved a $175 million project that will protect San Francisco’s ocean beach as well as key parts of the city’s sewage infrastructure at risk from climate-induced erosion of coastal cliffs.
The Ocean Beach Climate Change Adaptation Project approved Nov. 14 includes a 3,200-foot-long underground levee in Ocean Beach to protect sewer system infrastructure, which includes the city’s Lake Merced Tunnel and a nearby recycled water facility.
“These long-term improvements will protect vital wastewater infrastructure at risk,” Anna Roche, project director for the San Francisco Public Utilities Commission, said in a statement. “But just as important, this project provides the city with an opportunity to dramatically improve public use and accessibility along the waterfront south of Sloat Boulevard.”
Once the levee is completed, the dunes and related habitats will be restored. Maintenance of the restored beach and seawall will cost about $1 million a year, according to the commission. Relocating the wastewater infrastructure would cost $1.6 billion, according to San Francisco Water Power Sewer.
The proposal by the San Francisco Public Utilities Commission calls for diverting the Great Highway away from the narrowest part of the beach, building a multi-use public path more than 1 mile long overlooking the Pacific Ocean where it currently passes the road and a beach food. project that includes new sand as the shoreline widens 78 feet.
Additional elements include maximizing open space and recreational public access to the area through habitat restoration. A waterfront development permit for the project was approved in November.
Construction on the project is expected to begin in late 2027.
Coastal erosion in Ocean Beach has severely affected road and water infrastructure.
Photo courtesy of the California Coastal Commission
The commission’s report on the Ocean Beach project says coastal erosion is threatening the most marine component of the commission’s combined sewer system, the Lake Merced Tunnel, a 14-foot-diameter pipe located under the Great Highway. “With rising sea levels and more intense storms, erosion is only expected to worsen,” the report states, adding to the urgency of protecting critical coastal infrastructure, habitats and beach
The Great Highway was originally built in 1929 and has been modified many times since then, including during the 1993 construction of the tunnel pipe that combines stormwater/wastewater flow and overflow storage.
As part of its overflow function, the tunnel contains combined stormwater and untreated wastewater flows during periods when the Oceanside Water Pollution Control Plan cannot treat the amount of inflow , such as during large storm events. If the tunnel is ever filled to capacity, the excess water is directed to the Pacific Ocean through a pipe that runs 3.5 miles offshore.
In addition to mitigating the impacts of erosion, the new project will protect the tunnel with shielding.
The reorientation of Great Highway away from the beach between Sloat and Skyline boulevards includes improvements at two intersections, while other needs include reorienting a bus stop and turn zone and reconfiguring the entrance to the San Francisco Zoo parking lot. The freeway relocation also includes a new beach and overlook access stairway, public restrooms and 60 parking spaces at the south end of the project replacing the current 30 nearby that will be eliminated with the changes.
Habitat restoration includes removing revetments and debris previously used to reduce erosion, reshaping the bluff to increase open space accessibility, replanting native vegetation, and replacing sand
