Sand on the Run : Conveyor Feeds a Fresh Supply to Eroded Beaches

A conveyor belt more than a mile long is bringing first aid in the form of sand transfusions to the ailing Dockweiler and El Segundo beaches.

Winter storms and summer surf have removed sand from the beaches, and natural forces no longer replenish the supply. So contractors for the city are moving sand in from the Hyperion sewage treatment plant, where more than a million tons of it is being excavated for an expansion project.

Workers are moving the sand on an elevated conveyor belt that extends north from the construction site, goes through a tunnel under the four-lane Vista del Mar, then heads up the beach.

On Feb. 20, workers began relocating the first of 670,000 cubic yards of sand, enough to form 22 acres of new beach.

Cooperative Effort

The project is a cooperative effort between Los Angeles County, which is responsible for the beaches, and the city of Los Angeles, which has the problem of disposing of sand from its sewage plant site.

“Eventually, without replenishment, the beaches will continue to erode back until there are no beaches at all,” said Gregory Woodell, a planner for the county Department of Beaches and Harbors who organized the $4.5-million effort.

“That has already happened at El Segundo,” Woodell said. “At high tide the water is on the rocks.”

Officials say the new sand will turn El Segundo into another beach that the public can use.

The sand, which has been tested for impurities, is coming from the same source that helped build the string of broad beaches that made the area a recreational haven.

Early Excavation

“The idea to use the sand for the beaches started when I found out they were going to expand the plant,” Woodell said. “A large majority of Dockweiler, Venice, Santa Monica and Will Rogers beaches were formed by sand excavated during the building of Hyperion.”

About 14 million cubic yards of sand excavated from the Hyperion site was placed on Dockweiler and other beaches in the late 1940s. Three million cubic yards was added to Dockweiler from 1960 to 1962, during the construction of Marina del Rey. There has been no major effort by the county to replenish its beaches since then.

In the earlier Hyperion excavations, the sand was moved by mixing it with water--forming a slurry--and pumping it through a pipe onto the beach. The contractor this time, Chadwick & Buchanan of Long Beach, is using a conveyor belt because it can move more sand more quickly, Woodell said.

Work at Dockweiler must be completed by March 15 so that it will not harm grunion, the small fish that slither out of the water every spring to lay their eggs on the sand.

Half a Million Tons

Dockweiler will get 330,000 cubic yards of sand, weighing about half a million tons, which will extend the width of the beach by 110 feet, Woodell said.

The conveyor belt is built in sections so that it can be easily moved. Workers will add sections as they make their way up the beach until the belt extends 1 1/2 miles from the construction site.

For the Dockweiler phase of the project now under way, the conveyor belt extends from the construction site in the El Segundo dunes through a 9-foot-diameter tunnel under Vista del Mar. From there, the belt runs north atop the bluff until it descends to the beach just south of Imperial Highway. The belt will travel more than half a mile on the beach from there at its maximum length.

The process starts when the dark, wet sand excavated at the construction site is moved by bulldozers into a large metal hopper. The sand drops through the hopper at a measured rate onto the conveyor’s hard rubber belt. Rollers under the belt are tilted at an angle so that the belt takes on a concave shape, enabling it to hold the sand as it is moved along the conveyor.

Mounds Formed

At the end of the line, the sand is dumped onto the beach, then arranged in large mounds by bulldozers. Finally, other bulldozers push the sand into the ocean, extending the edge of the beach.

The belt, elevated several feet by a metal frame supporting the rollers, can move about 1,000 cubic yards of sand per hour, said Walter Naydo, an engineer for the Hyperion engineering design division of the city’s Public Works Department. Portable diesel generators power the belt’s electric motors.

By April 1, workers will move the conveyor sections into position for the second phase of the project, in which severely eroded El Segundo Beach will get 340,000 cubic yards of sand. The new sand will widen a 3,000-foot stretch of beach by 210 feet.

Work on El Segundo Beach can continue through the grunion run because that beach has eroded to the point where the grunion cannot use it, Woodell said. Work at El Segundo will be completed in late June.

Cost Projection

Larry Charness, chief of planning for the county’s Department of Beaches and Harbors, said the project will cost the city no more than it would to truck the Hyperion sand to an inland dump.

Before the urbanization of Los Angeles, beaches were replenished with sand that was carried by streams to the ocean.

“Most of the upland sources of sand have now disappeared,” Charness said. “The stream courses have been dammed or channeled. Man has altered the watershed. A lot of the sand that came down as eroded material is now stopped upstream. We are now dealing with a finite amount of sand.”

The new sand will more than replace what was washed away by January’s fierce storms, which reduced the width of Dockweiler by 50 to 75 feet, Charness said. The beach was an average of 520 feet wide before the storm, meaning that more than 10% of it was lost.

An 8-foot-high chain-link fence on both sides of the conveyor belt will protect curious beach-goers. Some parts of the beach may be closed for a short time to allow bulldozers to spread the sand, officials say.

Although one goal of the project is to restore the beaches so that they can accommodate the big summer crowds, officials say the work also will save money in the long run.

“The beach is really the only defensive structure we have against storms,” Charness said. “It protects public and private property from costly damage.”