Plan to Manage Coastal Erosion Takes Shape

By Thomas K. Pendergast 

The cliff face along the coast near the City’s southwest corner, just west of the sewage treatment plant, is slowly crumbling into the ocean.

For more than a decade, multiple city and state agencies have been pondering what to do about the erosion stripping this stretch of coastline as the Pacific Ocean reshapes it; but now a solid plan is beginning to emerge. 

The overall concept of the plan is loosely called “managed retreat” and it involves many things, including construction of a new walking trail along the cliff-top above the coastline, which is now being designed. 

This view looking north along San Francisco’s southwestern edge shows the area where coastal erosion mitigation measures are being planned. Photo by Thomas K. Pendergast.

The project has been allocated $2 million for a multi-use trail following along approximately where the highway is now, and also a new parking lot where Skyline Boulevard currently meets the Great Highway. 

It will be used by both pedestrians and cyclists, while also providing access to the shore. 

The Ocean Beach Master Plan (OBMP) produced by the San Francisco Bay Area Planning and Urban Research Association (SPUR) outlines the managed retreat strategy to allow for pulling back from the present coastline, while still protecting important city infrastructure – specifically the wastewater pipes and associated infrastructure at the Oceanside Water Pollution Control Plant. 

This strategy includes four important parts: a buried seawall to protect the Lake Merced Tunnel; creation of a multi-use trail and parking lot; elimination of Great Highway between Sloat and Skyline boulevards and diverting traffic around that area via the intersection of Skyline and Sloat boulevards; and replacing the restrooms at Sloat and the Great Highway with a new restroom building and a small plaza area. 

Anna Roche is a project manager with the San Francisco Public Utilities Commission (SFPUC) which is responsible for the sewage plant and the tunnel.  

“The Ocean Beach Master Plan was the underlying document that was developed for this work and it had multiple objectives that we were trying to address,” Roche said. “One is to protect critical wastewater infrastructure. That is what the low-profile wall will be doing. We also are addressing climate change and sea-level-rise-induced erosion. In order to have that element addressed in the project, we need some additional land mass to work within and that’s why we’re implementing what we’re calling ‘managed retreat.’” 

Roche described managed retreat as a technique that is used to give the ocean additional space to accommodate sea level rise. 

“So that’s why we’re removing the Great Highway in between Sloat and Skyline and opening that area up,” she said.

While some have argued that a seawall above the sand (like the O’Shaughnessy Seawall that runs along Ocean Beach to the north) might save the Great Highway, Roche said the complexity of dealing with such a big problem requires the involvement of so many state and local authorities.

“You have to think about the Coastal Commission, which is the regulatory agency here, and they don’t want things like seawalls,” Roche explained. “This is a blended approach, which is why we’re developing the project the way that we are. It’s a low-profile wall and it’s meant to be basically invisible to the public. And what it does is it provides protection for our facilities and it also helps maintain a sandy beach. In other words, you end up with a still-usable recreational area.” 

Roche mentioned the consideration of the human – rather than strictly engineering – element that is underlying the project.

“This is meant to be a more subtle (than the O’Shaughnessy Seawall) approach to protecting infrastructure while still allowing for that sandy beach. People should be able to surf and not have a cement wall in front of them as they’re coming off the curve of the wave,” she said.

Julian Espinoza, a spokesperson for the National Park Service at the Golden Gate National Recreation Area, which lies at the northern end of Ocean Beach, also emphasized in an emailed comment the importance of keeping the beach intact.  

 “The area around Ocean Beach is in a constant state of change as a result of coastal erosion,” Espinoza wrote. “We have partnered with local public agencies, including those at the City and County of San Francisco, to address sea level rise, protect infrastructure, restore coastal ecosystems and improve public access to the beach. 

He said the planning efforts have taken place over the course of several years.

“(The plans) examine the long-term future of the beach, which remains one of the most popular locations within Golden Gate National Recreation Area,” he said. “The past year has shown us the importance of outdoor spaces in ensuring our physical and mental well being. 

“In 2020, even while visitation at our park dropped overall when compared to 2019, visitation at Ocean Beach increased by more than 20%,” Espinoza said. “We are pleased to know the beach has been a valued source of recreation for San Franciscans during this difficult time and recognize its particular significance to Sunset neighborhood residents.” 

Roche said SFPUC must have its permit applications submitted by December and expects construction to start in early 2023. 

It had to move the construction back because of delays, although more so because of bureaucratic factors than the pandemic. 

“This project has a lot of people at the table, a lot of different agencies that have different interests,” Roche said. “The complexities have slowed us down a little bit, but we actually weren’t really impacted by COVID because we’re not in a stage in the project for work in the field. So, since everybody’s able to work from home, we’ve been able to do fairly well in terms of keeping up with the schedule.”

The pandemic did, however, cause a delay to a public meeting.

“Because of COVID, we had to redesign how we would do that and had to do it virtually. And because the (SF) Planning Department hadn’t really done that … it did slow down that process. But the overall CEQA (California Environmental Quality Act) document, as of right now, is still targeting a release this fall, which is what we had anticipated all along.”

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