Shifting Sand to Save Beaches : A Unique Machine May Be Solution to Erosion in Oceanside

The strange contraption that dangles just above Oceanside Harbor resembles a gigantic tarantula, sucking up massive mouthfuls of sand and spitting it out along the city’s badly eroding beaches.

This $12-million contraption, which officials say is the only one quite like it in the world, has survived a shaky start. Now it is finally showing promise of helping to solve one of Southern California’s serious environmental problems: vanishing beaches.

“We’re leading the way,” said Jim Crum, project manager for the U.S. Army Corps of Engineers, which designed the system of diesel engines, jet pumps and fluidizers that scoop sand from the harbor bottom and spread it on the sparse beach via a two-mile-long buried pipeline.

Oceanside Deputy City Manager Dana Whitson is convinced the experimental device--blandly named the “sand bypass system”--is beginning to prove it can help save beaches that would otherwise become covered with cobbles.

“The technology being used here is really pretty revolutionary,” Whitson said.

How well the experiment turns out is critical to Oceanside, where an estimated 3 million beach visitors, including a multitude of loyal surfers, are expected this year.

Yet the width of the city’s gleaming beaches is narrowing by an average of 5 feet a year, and one part actually withered from 170 feet wide to a mere 30 feet between 1966 and 1977, a period that saw numerous coastal storms.

Amid high expectations, the sand bypass system was first cranked up in mid-1989, but the results were disappointing, as only a paltry 200 cubic yards of sand a day reached Oceanside’s beaches.

The amount was certainly more than the 20 cubic yards that a double-loaded dump truck could carry to the beach, but it was nowhere near the quantity needed to feed the city’s sand-starved coastline.

Since then, a design innovation has increased sand deposits to about 600 cubic yards a day, and officials are confident the amount will reach 2,000 cubic yards a day when summer currents pull more sand into the harbor.

Eventually, the system is predicted to move 400,000 cubic yards annually along the southerly beaches, enough to help rescue beaches in Oceanside and perhaps neighboring Carlsbad.

Some of that sand will trickle even farther south to ease critical beach erosion a bit in other parts of the county.

It would take more like 30 million cubic yards of sand to rebuild the county’s beaches, then another 90,000 cubic yards a year to maintain them, according to a $6 million federal study for the San Diego Assn. of Governments, a regional planning agency.

The draft study of the coastline from Dana Point in Orange County to the Mexican border found three trouble areas: the entire shoreline from Oceanside Harbor down to Torrey Pines and Scripps beaches in San Diego; Ocean Beach in San Diego; and Silver Strand State Beach in Coronado and all of Imperial Beach.

“In Southern California, San Diego County is a lot worse off than Orange or Los Angeles counties,” said Steve Sachs, a senior planner at Sandag, which soon will hold public hearings on the report. The coast is steeper in San Diego County and unprotected by any offshore islands, he said.

Even so, nearly all the Southland has suffered from beach erosion caused by nature and man.

The region’s arid climate doesn’t bring many storms to wash sand down along rivers and streams to the coast. Worse, urban development has brought dams and reservoirs that also stop sand from reaching its coastal destination.

Oceanside Harbor became what Crum called “the major culprit” to the city’s beach erosion problem during World War II, when the federal government constructed vast Camp Pentleton to train Marines for combat in the Pacific.

The base included a boat harbor and jetty which thrust out into the ocean and interrupted the natural southerly flow of sand, trapping it in Oceanside Harbor. Not only have sand-robbed beaches sometimes become barren, but the sand buildup also menaces harbor navigation and requires frequent dredging to clear the way for boats.

Frustrated officials were searching for a way to restore the beaches long before the sand bypass system came along.

Once, in the early 1980s, officials declared war on beach erosion and trucked in 900,000 cubic yards of sand from the nearby San Luis Rey River. But in almost no time, ocean tidal action had washed away their expensive effort.

“The next year, the sand was all gone,” Crum recalled. “We learned that depositing large amounts of sand on the beaches does not help stabilize it.”

In 1981, after especially brutal storms battered the city’s beaches, Congress approved the bypass project which began operating in June 1989 after disappointing setbacks.

There were so many technical failures, repairs and delays that the original contractor was replaced by Healy Tibbitts Construction Co.

“They had a lot of start-up problems,” said George Armstrong, supervisor of the Beach Erosion Branch of the state’s Department of Boating and Waterways.

Even after the system began pumping, the results weren’t exactly a cause for celebration. The system worked to only 30% to 40% efficiency, largely because the two jet pumps had a limited range. They would suck up the sand within a small area, leaving a crater. Then they would have to be shut down until currents refilled the crater.

Officials noticed that the beach looked slightly fatter with sand, but “it was not having a great effect,” Crum said.

Things improved in November, when the Corps of Engineers installed devices called fluidizers.

A fluidizer, attached to each jet pump, is a perforated pipe that extends along the harbor floor. The fluidizer forces water out the holes that loosens sand and allows it to flow toward the jet pumps. The result: sand is drawn in from a wider area, allowing a more continuous pumping supply.

Whitson said the fluidizers “cause sand to keep replenishing the craters so you can keep operating for longer in the day.”

Different types of sand bypass systems are in use elsewhere, such as the Nerang River in Australia and the Indian River Inlet in Delaware.

But the Oceanside experiment uses the most complex system and is the only one operating at a coastal harbor. In addition, it has been the first to add fluidizers.

“This is the only place in the world where jet pumps and fluidizers are used together,” Whitson said.

Oceanside’s experiment has raised hopes that sand bypass technology will become a cheaper alternative to traditional harbor dredging that keeps sand deposits from interfering with boat navigation.

“The lessons learned in Oceanside might lead to bypass systems in other harbors on the Southern California coast,” Crum said.

Officials are generally optimistic that the sand bypass system will make a difference to San Diego County’s huge beach erosion problem.

“The most direct effect will be on the beaches in Oceanside, but there’ll be residual effects all the way down the coast,” Crum said.

Sachs of Sandag stressed that whatever the bypass system’s success, it still will take a costly program and a long-term effort to restore the county beaches.

It’s estimated to cost $150 million to place about 30 million cubic yards of sand on the county’s anemic beaches, and $5.5 million a year to maintain the beaches, says the federal shoreline report. The sand would likely come from offshore sand bars and water storage reservoirs.

And there is some skepticism about whether the Oceanside bypass system will deliver enough sand to rescue beaches.

Armstrong, the state Boating and Waterways erosion expert, said, “I think it may have potential, but I don’t know if it has enough capacity to help down-drift beaches.”

Yet it won’t take long to prove whether the bypass lives up to its potential, according to Crum.

“We’ll pump all summer, and come next winter, we should see if we’re getting much buildup on Oceanside’s beaches,” he said.

Sand Bypass Operation

At left in detail drawing, a 110-foot-long hoist barge with pumping equipment sucks up sand trapped at the breakwater of Oceanside Harbor. The barge operates at the breakwater during winter months, when sand accumulates on the barrier’s seaward side. Then, when ocean currents change in the summer, the barge is moved to the harbor’s main entrance channel to continue vacuuming sand through jet pumps. At top in drawing, a booster pump station near the south jetty is used to force the sand out through the long pipeline and deposit it along eroded beaches.