SPUR suggests abandoning part of Great Highway to fight erosion

The ocean’s very, very slow offensive against Ocean Beach (in the form of gradual but constant erosion) endangers access not only to the beach itself but also to everything that borders it.

Urban design think tank SPUR released a proposal last week for how best to fix the beachfront, most notably “South of Sloat, where the erosion is severe and access must be coordinated with numerous coastal protection and roadway efforts.”

Beach erosion is hardly a new problem on the western side of San Francisco. As the Surfrider Foundation observed in 2012, the city has been fighting the ocean for almost as long as San Franciscans have been using the beach:

“Over the years, the City has defended its shoreline boundary by dumping rocks, adding concrete fill, planting non-native dune grass and building seawalls.”

SPUR

(Storms unearthed the remains of those old sea walls last year, like the bones of great engineer projects long dead.)

But the usual suspects—sea level rise and climate change—are accelerating the process now. Last November the city removed 70,000 cubic yards of sand from the north end of the beach and trucked it down to the south end as a stopgap.

As SPUR notes, “South of Sloat Boulevard, coastal erosion threatens the Great Highway, beach parking lots, and—most significantly—critical wastewater infrastructure.”

The city is considering “a subsurface, low-profile structure that would protect vulnerable segments of critical wastewater infrastructure [...] The design, environmental review, and permitting of the long-term strategy is expected to take until 2021 to complete.”

SPUR instead suggests redesigning nearby streets and letting nature take over some areas. Their three phase plan in the south starts with a slightly confusingly titled phase zero:

This phase represents thinking about what could be improved at South Ocean beach immediately, without changing the roadway footprint. It includes the reorganization of concrete barriers and parking areas, creation of a safe pedestrian route along the shore, and informational signage.

Phase one calls for narrowing the Great Highway to two lanes south of Sloat, temporarily turning the now closed lanes into parking, and using the concrete barriers already scattered along the beach to redirect traffic.

Phase two is the big one, calling for rerouting the southern portion of the Great Highway and letting nature take over abandoned areas of the bluffs to create a barrier:

The coastal trail which connects South Ocean Beach with Fort Funston and Lake Merced will replace the Great Highway between Sloat and Skyline Boulevards. [...] This plan provides better and safer beach access, and connects the key open space resources in the area, while protecting our vital pieces of infrastructure from Sea Level Rise.

The paper acknowledges that some of the suggestions are unlikely to actually happen, but maintains that the design, developed in conjunction with landscape architects from AECOM, is the best bet.

• New Ocean Beach Designs [SPUR]
• History of Ocean Beach Erosion [Surfrider]
• Old Timey Beach Ruins Unearthed [Curbed SF]
• Coastal Erosion Management [NPS]