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Report: Structures could cut beach-building costs

Building offshore breakwaters and artificial reefs to prevent waves from pounding the beach could drastically cut the cost of fighting coastal erosion in Oceanside, Encinitas and Solana Beach, a new San Diego Association of Governments study states.

The structures help keep sand on beaches and reduce the need for pricey sand replacement programs, according to the study. During their 50-year life, they could save as much as $24 million, cutting beach protection costs in half in each of the three coastal cities.

Jamie Scott Lytle / Staff Photographer

Beachgoers line the sand in Oceanside, with Carlsbad beaches in the background.

"At some spots, it's cheaper to build something out there than to keep pumping sand on the beaches and watch it wash away," said Seamus Innes, a coastal engineer with Moffatt & Nichol Engineers, which did the study for SANDAG.

Even though it predicts huge savings, the findings are far from a final solution to beach erosion.

Breakwaters ---- concrete or rock walls built parallel to the shore to block waves ---- would protect the most beach for the least money. But some surfers and naturalists object to them because they disrupt surfing breaks and alter the shoreline.

Artificial reefs ---- large bags of sand piled on the ocean floor ---- are more palatable to some environmentalists. But whether they actually protect sandy beaches remains unknown, especially along the California coast.

And neither sand-retention device would save money in Carlsbad, Del Mar, San Diego, Imperial Beach or Coronado because beaches erode at a slower rate in those cities, the study said. The pros and cons of doing nothing to protect beaches were not considered in the study.

Despite the findings, some city officials say they don't want concrete and rocks.

The report "is not a wholesale blessing of any and all hard structures on the shoreline," Encinitas Councilman James Bond said, adding that he would prefer to experiment with the softer artificial reefs.

Some people say maintaining a natural shoreline by continually adding sand and not building any structures is worth the higher price.

"If we're going to do sand replenishment, it has to be an ongoing program like filling potholes in a road," said Marco Gonzalez, chairman of the Surfrider Foundation's San Diego chapter. "(Breakwaters), in our view, are unacceptable."

Keeping sand on the beach is a core part of SANDAG's beach preservation strategy because replacing the stuff is so costly once it washes away.

SANDAG launched a $17.5 million project in April that will put 2 million cubic yards of sand on 12 county beaches by the end of the summer. But the sand is only expected to last a few years, and no money is set aside for future beach-building.

Even though there are a lot of questions and concerns regarding the study, its finding will give each city a clear look at the long-term costs of protecting beaches with and without structures, SANDAG planner Steve Sachs said.

SANDAG's Shoreline Preservation Committee will discuss the study at noon Friday at 401 B St., Suite 800, San Diego.

Because only three of the county's eight coastal cities would benefit from the sand-retention structures, SANDAG probably won't launch a regional effort to build them, Sachs said.

That would leave Encinitas, Oceanside and Solana Beach on their own to find the millions of dollars needed to build the structures.

Breakwaters provide the most bang for the buck, according to the study.

Oceanside, Encinitas and Solana Beach would have to spend $33 million each to build a 1,000-foot-long breakwater and maintain a 17-acre beach for 50 years.

The cost includes depositing 1.1 million cubic yards of sand on the coast, building a breakwater, and adding an additional 620,000 cubic yards of sand every decade.

Without a breakwater, each city would need to spend $57 million to maintain a 17-acre beach for 50 years.

Using an artificial reef to maintain a small 2-acre beach for 50 years is the cheapest alternative at $9 million. Just replacing sand, without adding a reef, to maintain a 2-acre beach for 50 years would cost $20 million.

Contact staff writer Spencer Soper at (760) 943-2313 or ssoper@nctimes.com.

7/11/01

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