Oceanside Pumped Up Over Sand Replacement

Times Staff Writer

Back in 1942, at the height of the war effort, the military built a boat basin on the Camp Pendleton Marine Corps base just north of here. In the years that followed, the civilians who lived in this seaside city noticed something strange taking place: The sand on their beloved beach was disappearing.

It didn't take long to find a culprit.

As many coastal experts saw it, the rock breakwater built to protect the boat basin was blocking the natural flow of sand along the coast. When the breakwater was lengthened in the early 1960s to shield the newly built Oceanside Harbor from the surf, the erosion worsened.

Now, a solution to the prickly problem may be at hand. Construction of a revolutionary, federally funded $5.5-million system of pipes and pumps designed to help sand find its way back onto Oceanside's beaches is nearing completion. Testing is to begin early next year.

Beaches as far south as Del Mar could benefit from Oceanside's experiment.

Called a sand bypass system, the contraption is designed to work much like a vacuum cleaner, sucking up sand trapped by the rock breakwater and depositing it on the beach about a mile to the south.

Oceanside officials hold high hopes for the project, saying that it should not only help put sand back onto the beaches but also keep the mouth of the municipal harbor unclogged.

In years past, sand has often built up in the harbor mouth, creating reefs and shoals that pose a danger for the pleasure boaters who use the entrance channel. To cure the problem, the mouth is dredged about every other year at a cost of $2.5 million to the federal government, which usually foots the bill.

But the sand bypass, Oceanside officials say, should change all that.

"I think it's a bang-up idea," Councilman Walter Gilbert said. "I like it. If it works, and I see no reason why it shouldn't work, the government will save money, we'll get our harbor cleared on a continuing basis, and we'll get sand on the beach. I think it's a winner all the way around."

If the system does succeed, it will be none too soon for Oceanside officials and businesses. City officials say that the erosion of Oceanside's beaches--the city's prime tourist attraction--has hurt its popularity as a travel destination. Moreover, the anemic beachfront has provided a less effective barrier for shoreline homeowners against the pounding effect of waves whipped up by winter storms.

Through the years, Oceanside and other communities up and down the county coast have tried a spate of gadgets and gimmicks to stem the flow of sand, but most have done little to keep the sand on the beaches.

In Del Mar and Carlsbad, a sausage-shaped device called a Longard tube was planted parallel with the shore in hope of trapping sand but it met with little success. Oceanside dumped nearly 2 million cubic yards of sand onto its shoreline in the early 1980s, but much of that was washed out by waves during the severe winter storms after that.

Most coastal experts and government officials see the sand bypass system as a quantum leap over those previous anti-erosion efforts--and something that should prove far more effective.

"It's a real good experiment, and I hope they do what it takes to make it work," said Reinhard Flick, a staff oceanographer with the state Department of Boating and Waterways. "The concept is a good one. Now the engineering has to be done to carry it out."

Though the idea looks inviting on paper, the task of actually making the function effectively promises to be a challenge. The system is the first of its type on the West Coast and is still considered to be experimental. Even the project's designers at the Army Corps of Engineers are hesitant to make any predictions about how well the bypass will work.

"Whether or not it will do what's intended is a good question at this point," said Alan Alcorn, a project manager for the Army's engineers. "But the hopes are fairly high for this system to operate well."

Alcorn said initial start-up tests on the system are scheduled for late January and the first attempts to vacuum sand is expected in February.

The system is fairly simple from a mechanical standpoint. The key feature is the jet pump, an arch-shaped length of two-foot diameter pipe about as long as two full-sized Cadillacs. Water is forced through the pipe, creating a suction that vacuums sand from the ocean bottom through a six-inch nozzle near the arching end of the gizmo.

Currently, the jet pumps are being pieced together by workers on land. In the coming weeks, the contraptions will be lowered by crane into the water at two different sections of the harbor and installed by a hard-hat diver.

A single jet pump will be placed on the northern side of the harbor breakwater, where it can capture sand blocked by the rock structure. Two more pumps will be placed in the harbor entrance, but future phases call for installation of up to 10 extra jet pumps in that area as needed.

To help handle the pumping chores, the Army engineers have designed a barge outfitted with sophisticated mechanical gear.

During the summer months, when waves tend to push the sand to the north and into the harbor mouth, the barge will be stationed at the entrance to the channel, operating the jet pumps there. In the winter, when sand moves south and piles up against the northern side of the breakwater, the barge will be moved to that side.

The barge will only be in the water a fraction of the time. Eager to make sure the platform does not become a victim to the waves, the engineers have devised a system for raising the barge out of the water.

At both the harbor mouth and the northern breakwater, sets of thick steel pilings have been erected. Using an advanced winch system, the barge will hook onto the pilings and then hoist itself out of the sea.

The entire system will be connected to a large, electrical-powered booster pump, which is housed in a boxy, tile-roofed building at the foot of Harbor Beach near the southern side of the entrance channel. The booster pump, which can move up to 5,700 gallons a minute, will help send the mix of water and sand cascading down a pipe to two discharge points in the surf off 7th and Tyson streets. Ultimately, plans call for still another discharge outlet even further south, at Wisconsin Street.

To analyze the performance of the system, a five-year monitoring program is planned. Tests will be used not only to determine how efficiently the bypass is running, but to estimate how much sand is being removed from the harbor and how much sticks on Oceanside's beaches.

If all goes according to plan, Oceanside officials hope the bypass system will pump up to 400,000 cubic yards of sand each year onto the beach. According to Flick, that on-going influx of sand will likely prove more beneficial than the massive efforts to dump millions of cubic yards onto the beach at one time.

"When you put a half million yards or so on a beach that is all cobble, the chances of erosion are greater than when there is a steady stream of sand such as we will have with the bypass," he said.

Still, the proof of the system's effectiveness will only come with time. And if it proves successful, it will mean a renewed source of sand for beaches as far south as Del Mar because of the natural drift of sand south along the coast.

"We know it should help somewhat, we just don't know to what degree," said Dana Whitson, Oceanside's special projects planner. "In the best possible of worlds, the bypass will help stabilize all our beaches."

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