SPUR Ocean Beach Master Plan for San Francisco – Strategies for Great Highway

Developed by the San Francisco Planning and Urban Research Association (SPUR), the Ocean Beach Master Plan (OBMP) provides a long-term strategy for responding to current and future sea-level rise impacts along the 3.5-mile stretch of San Francisco’s Ocean Beach, and provides recommendations for adapting the Great Highway, which runs adjacent to the beach. The strategy focuses on the protection and relocation of transportation infrastructure, including: (1) rerouting the southern portion of the Great Highway; (2) protecting and restoring the shoreline and beach; (3) reducing the width of the Great Highway; (4) repairing seaside dunes; (5) facilitating faster travel between Golden Gate Park and Ocean Beach; and (6) improving bicycle paths and sidewalks near Ocean Beach. While the OMBP has no legal effect, it was developed in partnership with city, state, and federal agencies that are ultimately working on phased implementation of the plan.

Ocean Beach is highly exposed to erosive effects of the Pacific Ocean. During storms in 2009-2010, parking lot foundations and the highway shoulder were at risk of collapse due to erosion that at some places caused the beach to recede 40 feet inland. The receding shoreline threatens to damage critical infrastructure: the Great Highway, the Lake Merced Tunnel, and a wastewater treatment plant. The Great Highway, built on an artificial foundation of sand, is an important traffic artery for local residents and regional travelers alike. The highway and nearby parking lots have been undermined by erosion from storm events, but prior lack of coordination among regulatory authorities (including city, county, state, and federal entities) had hampered efforts to implement proactive countermeasures.

To assess future impacts to the Ocean Beach region, SPUR relied on climate projections provided in the State of California Sea-Level Rise Interim Guidance Document. The study assessed the potential impacts to the region based upon projections of 14 inches of sea-level rise by 2050 and 55 inches by 2100. Projected impacts for the study region include more frequent and more severe coastal storm surges and worsening erosion. Acknowledging the uncertainties inherent in projecting climate impacts, the OBMP suggested an adaptive management approach for the region, suggesting that localities undertake successive actions on the basis of physical triggers, such as a particular amount of beach erosion, instead of set timelines. This adaptive management strategy will allow recommendations to be implemented in a flexible manner, evolving as physical conditions change and political and fiscal challenges are addressed. 

The OBMP management strategy organizes recommendations within six “Key Moves,” the first three of which are most relevant to managed retreat of transportation infrastructure.

  • Reroute the Great Highway inland and away from the shore, offloading traffic from its southern portion onto minor roadways that are better protected from erosion. Consider allowing the southern reach of the Great Highway to be returned to recreational areas and parking. This portion of the Great Highway is now protected with boulder revetments, but it is frequently closed.
  • Consider a managed retreat strategy that would protect critical infrastructure while restoring the beach and improving recreational access. The Lake Merced Tunnel, a critical wastewater treatment asset overseen by the SF Public Utilities Commission, is buried deep within a large sand berm that forms the foundation for the southern portion of the Great Highway. By removing and relocating parts of the southern highway, the city could replace the current seawall protecting these assets with a longer, shallower defense system that dissipates tidal energy more effectively while providing more usable beach. The underground Lake Merced Tunnel would be armored with a low-profile structure made of stone or concrete, on top of which would be piled cobblestones that would absorb tidal energy, reducing erosion. Sand dredged by the U.S. Army Corp of Engineers would be placed atop the cobblestones to provide another layer of buffer, but would need to be maintained with consistent renourishment.
  • Narrow the Great Highway along the middle portion of Ocean Beach in order to facilitate a long-term retreat strategy and make space to restore dunes that are receding toward the highway. (However, implementing agencies are not proceeding with this “key move” from the OBMP.)

Because the OBMP has no legal effect, its funding and implementation is contingent on action by a range of agencies at all levels of government.  To facilitate implementation the plan lays out four concurrent “implementation tracks” that focus on different stages of study to inform decision-making (e.g., coastal engineering studies, traffic analyses, environmental impact reports for Great Highway relocation and roadway reconfigurations, etc.). The implementation tracks involve collaboration among multiple partners, including SPUR, San Francisco agencies (the Municipal Transportation Agency, the County Transportation Authority, the Recreation and Parks Department, the Public Utilities Commission, the Planning Department, and the Department of Public Works), and federal agencies (including the Army Corps of Engineers, and the Golden Gate National Recreation Area). The studies that were completed ultimately reinforced many of the recommendations for action included in the OBMP.

Referred to as the “Ocean Beach Climate Change Adaptation Project,” portions of the OBMP’s “key moves” 1 and 2 are currently being implemented in three phases by city, state, and federal agencies:

  • Short-term Improvements Phase - this early phase involves beach nourishment efforts and installation of sandbags along portions of the beach fronting on the Great Highway. It is designed to preserve public access and protect the roadway while engineering and design of longer-term solutions are being pursued. This phase began in August and September of 2012, when the Golden Gate National Recreation Area (GGNRA) partnered with the San Francisco Public Utilities Commission (SFPUC) to renourish the south end of Ocean Beach with 73,000 cubic yards of sand. In Fall 2015, the City received approval from the California Coastal Commission for a package of “soft” coastal protection measures, such as sand placement and sandbags, that can be taken in the interim period over the next six years should they be needed to counteract erosion from winter storms. The permit ensures that the City can act quickly to protect against coastal erosion without first having to obtain reactive emergency permits, while also committing the City to a timetable for obtaining permits for the longer-term measures recommended in the OBMP.
  • United States Army Corps of Engineers (ACOE) Beach Nourishment Phase - this phase will involve the beneficial use of dredged material to provide beach and infrastructure protection and minimize storm damage in conjunction with the other phased efforts to protect South Ocean Beach. Construction is anticipated to begin in 2021.
  • Long-term Improvements Phase - this phase of work draws heavily from the OBMP and will result in the “implementation of coastal management strategies that include managed retreat (i.e., recontouring the bluffs and removing the Great Highway between Sloat and Highway 35), removal of rubble and revetment rock from the beach and bluffs, continued beach nourishment, and installation of a low-profile wall to protect the Lake Merced Tunnel and associated assets.”1 Construction is expected to begin in 2023.  

The City of San Francisco and State of California are proceeding with other steps necessary to implement the OBMP. For example, some of the broad visions for addressing sea-level rise and coastal erosion developed through the OBMP planning process were transformed into a set of land use policies that have been incorporated into the City and County of San Francisco’s Local Coastal Program, which was approved by the California Coastal Commission in 2018.2 The Department of Public Works is implementing sewer and drainage improvements to better manage stormwater; and Caltrans is overseeing the addition of traffic signals and other intersection improvements at the intersection of the existing Great Highway and its new rerouting onto inland roadways. 

The OBMP was developed by the San Francisco Planning and Urban Research Association (SPUR), which is a member-supported nonprofit organization that provides planning assistance to the San Francisco Bay Area. SPUR has maintained a role as coordinator and advocate for implementation of the OBMP. The OBMP was funded by the State of California Coastal Conservancy, the San Francisco Public Utilities Commission, and the National Park Service. Funding was awarded in 2009 at the request of the Ocean Beach Vision Council, a task force appointed by former San Francisco Mayor Gavin Newsom.

 

This Adaptation Clearinghouse entry was originally prepared with support from the Federal Highway Administration. This entry was last updated on June 30, 2020.

 

 

Publication Date: May 21, 2012

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