Erosion and Climate Change Adaptation Projects
Click image to enlarge.
In the 1980’s and 1990’s, in response to the Clean Water Act, the San Francisco Public Utilities Commission (SFPUC) built the Oceanside Treatment Plant and associated wastewater infrastructure to protect coastal water quality from pollution and protect public health. Portions of this equipment were built under the City and County of San Francisco’s (CCSF) Great Highway.
Starting in the late 1990’s the coastal area south of Sloat Boulevard began experiencing chronic erosion which threatened the Great Highway and the most seaward component of our wastewater infrastructure – the Lake Merced Tunnel (LMT), a fourteen-foot diameter wastewater conveyance pipe. As climate change continues to cause sea levels to rise, shoreline erosion from storm driven waves is expected to worsen, further threatening the coastal infrastructure and causing the beach to narrow.
In support of a comprehensive solution to the erosion problem, the SFPUC actively participated in the development of the 2012 Ocean Beach Master Plan (OBMP)
, an inter-agency effort led by the San Francisco Bay Area Planning and Urban Research Association (SFPUR) to develop a sustainable long-term vision for Ocean Beach. The OBMP presents 6 key moves that are organized by geographical reaches and designed to be implemented incrementally over a period of decades. CCSF’s current efforts focus on South Ocean Beach and include 2 of the 6 key moves;
- Removal of the Great Highway between Sloat and Skyline Boulevard and
- The introduction of a multipurpose coastal protection/restoration/access system
This project will comprise the concepts developed through the OBMP and includes elements such as managed retreat, structural protection, access and recreation improvements, and beach nourishment through the placement of sand. In addition, this project will remove existing shoreline armoring placed during large storms by CCSF to protect the Great Highway. On behalf of CCSF, the SFPUC is leading the efforts to implement these 2 key moves under the Ocean Beach Climate Change Adaptation Project (Project). This work is necessary to protect the integrity of wastewater assets built in response to the Clean Water Act to protect public health and the environment, including the LMT, the Westside Pump Station and the Oceanside Treatment Plant.
The Project is being implemented in three phases: Short-term Improvements Phase, United States Army Corps of Engineers (ACOE) Beach Nourishment Phase, and Long-term Improvements Phase.
Short Term Improvements Phase
The Short-Term Improvements Phase will provide interim protection and improved beach access while the Long-term Improvements Phase is under development. The Short-term Improvements Phase involves beach nourishment activities (.ie. sand placement) and installation of sandbags at erosion hot spots along the southern portion of Ocean Beach fronting the Great Highway. This work is a critical environmentally-friendly approach that is protecting public infrastructure and improving beach access. The annual sand and sandbag placement activities in this Phase are informed by annual monitoring efforts required by CCSF’s multi-year Coastal Development Permit that commenced in 2015 and continues through 2021.
Status of Short-term Work
- Since 2015, over 160,000 cubic yards of sand have been transported from the northern portion of Ocean Beach where sand is plentiful to the area south of Sloat Boulevard most susceptible to wave-driven erosion
- Annual monitoring in the Winter of 2018-2019 determined that beach nourishment is required (~ 65,000 CY) in the Fall of 2019 to re-establish the sacrificial sand berms and cover the sand bags. Work is planned for November to December 2019
- The SFPUC will continue monitoring to comply with permit requirements and will initiate sand placement and/or sandbag work when triggered to protect critical infrastructure
United States Army Corps of Engineers Beach Nourishment Phase
The ACOE Beach Nourishment Phase involves designing and implementing activities that would place dredged sand from the San Francisco Bay Main Ship Channel (approximately 300,000 cubic yards) that is currently placed offshore of Ocean Beach, directly onto the beach south of Sloat Boulevard. This work will beneficially use the dredged sand to minimize storm damage and protect the beach, infrastructure, habitat and recreational access to the beach. Implemented in partnership with the ACOE, this Phase will work in conjunction with both the Short and Long-term Improvements Phases to protect Ocean Beach south of Sloat Boulevard. The design phase for the ACOE Beach Nourishment Phase is currently underway with construction anticipated in summer 2021.
Long-Term Improvements Phase
Status of Long-term Work
The Long-Term Improvements Phase is the result of extensive planning and analysis work, (e.g., Ocean Beach Master Plan and Coastal Protection Measures and Management Strategy) which is captured in the Alternatives Analysis Report and the Conceptual Engineering Report. This phase of work is expected to involve 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. This work will not only protect vital public wastewater infrastructure, but will also improve access, recreation, and habitat at South Ocean Beach. The Long-term Improvements Phase is expected to begin construction in early 2023 and last for 4 years.
- An Engineering Contract received Notice of Contract Award on September 27, 2018
- The Conceptual Engineering Report was completed on September 30, 2019
- 35% Design is under development
- An Environmental Consultant Contract received Notice of Contract Award on August 18, 2018
- Notice of Preparation is expected in early 2020
- The Ocean Beach Long-Term Improvements Phase is expected to begin construction in 2023
Rendering of the Lake Merced Tunnel with a low-profile underground wall providing protection (click image to enlarge).