Beach building in 'stage one'
by George Wiley
An ambitious beach building project that will eventually move 145,000 cubic yards of sand on shore to expand and renew a shrunken stretch of beach in Redondo Beach has started with the dumping of sand into a nearby depression offshore.
The sand is being hauled in from the boat channel in Marina del Rey and dumped in Redondo in about 45 feet of water, according to Mo Chang, chief of the Navigation Section for the Los Angeles District of the U.S. Army Corps of Engineers, which is overseeing the beach building effort.
Chang said the barging of sand to the offshore drop site will continue until about the end of February.
Beginning in March, the sand replenishment effort will move into phase two, Chang said, which will be the pumping of the sand from the offshore depression onto the beach in Redondo.
Chang said the two-stage format was chosen because it is more efficient than assembling the equipment to barge and pump the sand directly onto the beach from the initial barge used to transport the sand.
Chang said environmental studies of the effect of dumping the sand offshore as a first step indicate that there will be little or no long-term impact of shellfish such as clams that may be buried and killed in the sand dumping. "They can regenerate themselves and re-colonize themselves," he said.
Chang said the second stage of the replenishment effort; the actual moving of the sand onto the beach in Redondo will involve a different barge outfitted with a "pipeline cutterhead dredge." The dredge will break up any hard chunks of deposited sand and then suck the sand through a pipeline which will spray the sand, mixed with a lot of water, onto the beach. Crews will be on hand when the sprayed sand-water mix hits the beach to build dikes and guide the sand to prevent it from running back into the ocean. Gradually, the beach will be built up so that it is about 75 feet wider than it is now, according to project estimates.
Chang said one big question that can't yet be answered is what will happen to the offshore sand in the water if a sizable storm occurs between now and the time the sand is pumped onto the beach.
"We don't really know," he said. "Any storms may erode it."
The hope is that the sand may renew the beach for as much a decade before another replenishment effort is needed.
Chang said the offshore depression into which the sand is now being dumped was a "handy" site for holding the sand underwater until stage two could take place. The depression runs parallel to the beach and was created by a previous dredging effort that took sand from directly offshore and deposited it onto the beach.
Chang said the usual way of replenishing is to take sand from nearby offshore and pump it back up onto a beach. Previous Corps projects in the Channel Islands, in Ventura and Santa Barbara counties and near Oceanside had done just that, Chang said.
The sand now being dumped offshore in Redondo will be pumped onshore to replenish a stretch of badly eroded beach between Topaz Street and the Redondo Pier. The dredging, hauling and replenishment effort is a joint $8.1 million project between the Corps, the L.A. County Department of Beaches and Harbors, and the City of Long Beach. Sand contaminated by boat fuel is being used as landfill in Long Beach. The contaminated sand is appropriate as a substratum for landfill but not for replenishment of a beach such as Redondo's
The Redondo sand replenishment is the Corps' only such effort in the South
Bay, Chang said.
