October 14, 2008
Marina Del Rey to Be Dredged
By Kristin S. Agostoni
Sand and sediment clogging the south entrance to the Marina del Rey channel will be dredged this fall using technology designed to separate contaminants from beach-suitable sand.
The U.S. Army Corps of Engineers plans to pump the dredged material from the channel entry to a Dockweiler Beach parking lot, where a machine will extract polluted fine particles from coarse sand, a spokesman said.
The goal is to haul away the contaminants - estimated to be about 10 percent of the total load - and use clean, treated sand to replenish the beach, said Scott John, a project manager in the corps' Los Angeles district office.
Nearly two miles of pipe will link dredging operations at the channel entrance to the Dockweiler parking area, which sits just south of a county Department of Beaches and Harbors maintenance yard.
The process, which is expected to start next month and continue through December or early January, will leave the parking lot off- limits, but not the nearby bike path.
The Marina del Rey operation marks the first time the corps will use so-called hydrocyclone technology for a West Coast dredging project, John said, and officials believe that, if effective, it could signal changes for future proposals.
The technology aims to treat and reuse material taken from a contaminated site that would otherwise be sealed off in an underwater landfill or used as fill material for a port project, John said. Or, if neither are possible, it might have to stay put.
"A lot of sand is contaminated, and we can't dredge it because it's unsuitable," he said. "(The technology) has a lot of hope for uses in the future."
Members of a multi-agency contaminated sediments task force worked for two years to develop a pilot project for Marina del Rey.
The southern part of the channel is believed to be more contaminated than the northern entry point because it sits at the mouth of Ballona Creek, which carries pollutants from upstream.
A lack of local disposal sites for contaminated sediment and the expense of hauling the load away have made routine dredging operations there difficult, according to a California Coastal Commission report.
It indicates that the first batch of treated sediment will be tested - along with the water discharged from the process - to ensure the system is working properly and that the coarse sand is safe to place on the beach.
The commission approved the project in August.
Kirsten James, water quality director for Heal the Bay, said the environmental group favors using dredged sediment for beach replenishment or port projects over hauling it to upland disposal sites - assuming the treatment process is successful and meets established health standards.
The group also does not agree with burying the contaminants offshore, she said.
"It's basically putting your problems off," James said. "What we really favor is beneficial reuse."
The Army Corps of Engineers announced earlier this month it had awarded a $1.8 million contract to CJW Construction of Santa Ana to dredge about 50,000 cubic meters of material in and around the channel's south entrance.
Dockweiler visitors might initially smell "organic odors," John said, but they should dissipate as the wet sand dries out in the sun.
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