The City of Oceanside understands the importance of sandy beaches for protection of coastal infrastructure, recreation, and the local economy.
A year-long study was completed to identify feasible solutions to protect the beach from long-term erosion. Strategies were sought that would be environmentally sensitive, financially feasible, and have a reasonable chance of being approved. Six concepts were put through a multi-criteria decision matrix and ranked. As a result, four alternatives were developed and evaluated in the study.
Groins scored the highest strategy based on a multi-criteria analysis of technical performance, financial, and environmental considerations. A groin is a rocky structure built perpendicular to the beach, usually made of boulders or concrete. Sand bypass systems were among other recommended options reviewed in a analysis of relevant projects around the globe.
A pilot project consisting of groins and a sand bypass system was determined as the recommended plan as a result of the Beach Sand Replenishment and Retention Device Feasibilitity Study. The final design will start with a project that is adaptable and reversible, and informed by a scientific monitoring program led by Scripps Institution of Oceanography.
At a City Council Workshop on Wednesday, August 11, 2021, the Council voted 4 -1 to approve the plan, providing staff with direction to incorporate flexibility to design a project with maximum benefit to all of the City's beaches. The strategy is to begin with a pilot project of about four groins, and then, assuming success of the project, add more groins on an as-needed basis to other sections of the coastline in future phases. The groins would trap sand moving in the longshore direction. The majority of the public comments received at two public workshops were in favor of a groin system. The exact number, length, and location of groins will be determined in the next phase of the project with more public outreach.
Several sand bypassing systems were also reviewed for their applicability and utility in resolving the erosion issues in the City. A bypass system would transport pumped sand to City beaches via a network of underground pipelines. Junction boxes are proposed to allow for booster pumps to be added or for sand to be discharged at various locations. This system would be designed to be compatible with the US Army Corps of Engineer's annual Harbor dredging program. The installation of a fixed-distribution system would improve public safety and reduce the disruption to public access and beach uses during each dredging event.
In the interim, City staff are seeking opportunistic sources of sand for beach nourishment (potential sites include sand from El Corazon, San Luis Rey River, and the future Buena Vista Lagoon restoration project).
The project will require a significant amount of capital and operational expenditures. Financing strategies will be considered in concert with seeking state and federal grant funds.
Next steps in the process include issuing a Request for Proposals to perform design, permitting, and environmental work. Key agency stakeholder coordination and engagement will then occur with entities such as the California Coastal Commission, Camp Pendleton, Surfrider Foundation, and others. Further engineering analysis concepts and locations will occur. An adaptive management plan will be developed to address public, agency, and stakeholder concerns about potential impacts, and the plan would informed by a scientific monitoring program by the Scripps Institution of Oceanography.