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Hydraulic sand pump fails beach to beach, but may work elsewhere

Crews monitor a pump and pipeline last February at the beach near 55th Place. (Photo by Harry Saltzgaver, Grunion Gazette/SCNG)

Posted on November 24, 2020

A $300,000 study this spring has apparently proven pumping sand and water from one beach to the Peninsula isn’t feasible — but there may be hope for another option.

Last week, the Marine Advisory Commission received a report about the spring experiment. The idea was to use a pump and pipeline to move sand instead of the huge earthmover trucks used the last several years to replenish the beach in front of Peninsula homes.

In February, a large excavator dug sand and put it in a manmade pond to mix with water and feed the pump. The experiment tried several different lengths of pipe and mixtures of sand and water, but nothing close to the length that would be necessary to reach the Peninsula.

Elvira Hallinan, Marine Bureau manager, said the experiment showed sand could be moved, but that it looked like it would cost much more than trucks, and be less reliable.

“We would be talking about almost a mile of pipe,” Hallinan said the day after the MAC meeting. “It looks like it would cost more simply in manpower. The water-sand ratio is difficult to maintain, and when there are clogs, you have to take that pipe apart and put it back together again.”

Long Beach has spent between $100,000 and $300,000 each year since the mid-1990s moving sand from the beach near the Belmont Veterans Memorial Pier to the Peninsula. The prevailing current inside San Pedro Bay scours the beach in front of the Peninsula, eroding the sand away, sometimes to the point where there is only 10 or 15 feet between the water and the breakwater in front of the plank walkway.

The city uses the earthmovers and bulldozers to create a sand berm — a long hill — to protect the Peninsula from winter storms. Because the beach is so narrow, flooding still occurs occasionally.

Several different “solutions” have been tried over the last three decades. The effort that has appeared to work best is extending the beach into the water at a very gentle slope for up to 300 feet, taking the energy out of waves. But a single strong storm has taken much of that sand away more than once.

That has left the city replenishing sand each year to continue protecting the Peninsula, Hallinan said. The question is, how does the sand get to the Peninsula and where does it come from?

“We don’t believe at this point the pump and pipeline is viable,” Hallinan said. “What we’d like to do it to place the pump on a barge (where a source of water wouldn’t be an issue).”

And the source of sand, Hallinan said, could solve two problems at the same time, at least for the short term. The idea is to dredge the channel entrance to Alamitos Bay, on the other side of the jetty from the Peninsula beach.

“The channel will require dredging at some point,” Hallinan said. “If we invest in dredging alone, we’d be spending millions of dollars.”

At this point, the concept is just that — an idea. To try it, the city must get permits from the California Coastal Commission and likely the Army Corps of Engineers. It is a lengthy process to get those permits, even for a test project.

In the meantime, winter and winter storms are coming. It’s likely earthmovers and bulldozers will take over the beach again soon.

Source: presstelegram

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