A regional planning group is laying the groundwork for another large-scale sand project like the one that expanded San Diego County beaches a decade ago.
The previous effort, completed in 2012 at a cost of $28.5 million, took nearly a decade of planning and the coordinated work of local, state and federal agencies, according to members of the Shoreline Preservation Working Group, a branch advisory of the San Diego Association. governments.
Yet some of the restored beaches have been swept to the rocks in just a few years.
Other areas kept their coat fresh longer, but now almost everywhere the sand is gone. Different grades of sand were used, and studies show that the build-up bonded best where the restored material had the largest and heaviest grains.
Such lessons can help make another effort more economical and more sustainable, say scientists and coastal planners.
“We should do it again,” said Dr. Reinhard Flick, a research fellow at UC San Diego’s Scripps Institution of Oceanography, at the shoreline preservation group meeting earlier this month.
Sea level rise and erosion will eventually defeat any replenishment plans, Flick said. However, the ocean rises relatively slowly over the years, and restoring sand to eroded beaches can protect homes and coastal properties until people are forced to move inland.
Retention devices such as artificial reefs and groins, structures that can be controversial, also need to be considered, Flick said.
“Eventually we will have to pull back from the coast, but that’s decades away,” he said. “In the meantime, sand retention and sand feeding, if we’re going to keep sand on our beaches…go hand in hand.”
Sand is vital to San Diego County for a number of reasons. Wide beaches protect clifftop homes, highways, parks, and campgrounds from erosion, ocean waves, and powerful storms. In addition, the attractiveness of the coastline is vital for tourism which fuels the economy of the region.
SANDAG completed its first regional sand project in 2001. The material used was relatively fine then, and a series of larger than usual winter storms quickly washed away much of it. Scientists say a third project could focus more on delivering the heavier, longer-lasting sediments that accumulate in ocean deposits outside the surf zone.
Funding is the biggest hurdle for any sand replenishment project, another lesson learned from past efforts. The first step is to get coastal towns to commit financially, members of the preservation group said.
“We’re all in favor of this,” said Del Mar Mayor Dwight Worden, the group’s interim chairman. “A regional solution is the way to go.”
The renewed effort to find a regional solution follows a solo Oceanside proposal that seemed to get off on the wrong foot last year.
Oceanside City Council, without consulting its coastal neighbors, voted 4 to 1 in August 2021 to spend $1 million on plans and permits to build rock groynes and a sand bypass system. Mayor Esther Sanchez opposed the project, saying the California Coastal Commission, which generally opposes building permanent structures on the beach, will never approve it.
Oceanside’s move has come as a surprise to southern coastal towns, which fear the groynes will block them from the downstream sand flow along the coast. Studies show that the devices slow or stop the constant migration of sand carried by ocean currents, which helps some areas but hurts others.
Carlsbad, Solana Beach and Del Mar each passed resolutions opposing the Oceanside project. A better plan would be for SANDAG to take the lead in a regional plan that helps all cities, they said.
Several coastal towns in San Diego County have occasionally used local replenishment projects to build their beaches for decades.
Oceanside’s northernmost beaches receive sediment dredged annually at the mouth of the city’s harbor.
But the harbor sediments are fine-grained, do not last long, and are never transported very far south. The lower two-thirds of the Oceanside coastline has eroded into a narrow beach that is usually completely underwater at high tide.
In most years, harbor dredging produces around 250,000 cubic meters of sand, enough to keep the channel open and place material on the beaches closest to the harbour.
SANDAG’s regional project in 2012 produced a total of 1.4 million cubic meters, from three different offshore fields. The sand was placed in eight different locations in San Diego County, from Oceanside in the north to Imperial Beach in the south.
The previous regional project in 2001 was even bigger, pumping a total of 2.1 million cubic meters of material from beaches.
The 2012 regional project used the 2001 effort as a model and sampled sand from some of the same locations, SANDAG officials said. But escalating costs in 2012 forced the agency to downsize the project, so less material was obtained.
As a result, some sites that received sand in 2001, such as Torrey Pines State Beach, received nothing in 2012. Additionally, the City of San Diego had recently received sand on Mission and Pacific beaches from the dredging of the mouth of Mission Bay. did not need equipment from the second regional effort.
Several other beaches in San Diego County also receive regular replenishment from local projects.
Carlsbad gets much of its sand from the Agua Hedionda Lagoon, which has been dredged approximately every two years since the 1950s. Initially, excavation was necessary to keep the lagoon deep enough to supply seawater to the system. cooling plant at Encina Power Plant.
Another benefit of ongoing maintenance is that Agua Hedionda is the only lagoon in San Diego County deep enough to accommodate boating, paddle boarding, and other activities. Today, it continues to be dredged as seawater feeds the Carlsbad desalination plant, which provides 10% of the county’s drinking water.
One of the county’s most recently restored shorelines is found on its central coast at Cardiff State Beach in Encinitas.
Completed in 2019, the project salvaged sand from environmental restoration of the San Elijo Lagoon, which had been filling with silt for decades. Unlike other beach nourishment projects in the area, the beach restoration included wind fences and the placement of native plants to help hold the sand in place.
Several time-consuming planning, environmental, and engineering steps are required before any replenishment project begins. Environmental concerns such as grunion and lobster seasons must be taken into account, as well as the presence of marine mammals, turtles and nesting birds. But the most important thing is that it takes money.
SANDAG’s Coastal Preservation Group includes elected officials from each of the coastal town councils. They work with planners, landowners, and community and environmental groups to study projects such as sand retention and beach restoration.
The group, which normally meets quarterly, has scheduled a special session in April to further discuss the details of recruiting cities to contribute to the costs of another regional sand project.
Local money pays a small percentage of the total project cost. Typically, it’s used for things like feasibility studies and early planning to start the effort.
Construction costs make up the largest portion of expenses. In 2012, that included the huge cost of bringing a dredge big enough for the job to San Diego from the East Coast, said Shelby Tucker, project manager for SANDAG.
Grants pay about 85% of project costs, and the remaining 15% comes from local agencies such as cities, Tucker said.
Although the actual construction took only a few months in 2012, the planning, engineering and efforts to find financing began around 2005, she said.
“We didn’t get all the money at once,” Tucker told the task force. “We received it in three different fiscal years…divided into $6.5 million for three years.”
The largest source of funding for the 2012 project was the state Department of Recreational Boating and Waterways. Other sources include the Federal Minerals Management Service’s Coastal Impact Assistance Program and the California Coastal Commission’s Sand Mitigation Fund.
Different sources of funding may be available for the next sand project, said Anna Van, associate regional planner at SANDAG.
“Funding to mitigate disasters and climate risk has been a hot topic at the federal and state level lately,” Van said, so federal sources could include FEMA, the Federal Emergency Management Agency. .
Other possibilities include the California Office of Emergency Services, the State Department of Boating and Waterways, the US Army Corps of Engineers, and the US Navy.
“It will take time and effort for us to seize these opportunities,” Van said.
Oceanside council member Ryan Keim and Encinitas council member Kellie Hinze both said they would ask their city councils to help with a regional project.
Oceanside is heavily dependent on tourism and has been hit hard by beach erosion.
The southern two-thirds of the Oceanside coast has been eroded to rock revetments, and at high tide there is no beach at all. Residents and elected officials have worked for years to protect homes and vacation rentals from erosion.
Encinitas and Solana Beach have been working with the US Army Corps of Engineers and other agencies for more than a decade on a major beach restoration project that is finally ready to go. The collaboration will take sand from offshore deposits and place it on city shores every five to 10 years for the next 50 years.
“We look forward to the 50-year sand replenishment,” Hinze said.
But that sand will only be distributed south of Beacon’s Beach, while Encinitas and Solana Beach, like much of California, have other beaches that need nourishment.