Officials at the Los Angeles County Sanitation Districts say that efforts to impose tighter federal treatment standards at the Carson sewage plant could backfire, indirectly causing the release of DDT embedded in sediment off the Palos Verdes Peninsula.
The agency is attempting to win a waiver from federal regulations requiring it to remove more solids from the 365 million gallons of effluent it pumps daily through ocean outfalls south of the Palos Verdes Peninsula.
Environmentalists active in efforts to clean up Santa Monica Bay say the upgraded treatment would spare the bay from significant quantities of oil, grease, toxic metals and other pollutants.
But the sanitation districts argue not only that the effluent is safe, but that the solids it carries are urgently needed because they "cap" a layer of bay sediment contaminated by hundreds of tons of the pesticide DDT discharged into the ocean in the 1950s and '60s.
"You don't have to be an Einstein to realize that if there are no more deposits, the cap will erode away," said Joe Meistrell, a biologist who supervises the sanitation districts' ocean monitoring program. "The genie would be out of the bottle."
The environmentalists disagree. Said Mark Gold, staff scientist with Heal the Bay, a Santa Monica environmental group, "You don't solve this (DDT) problem by covering it up with another one."
The pollution debate stems from the sanitation districts' request for a federal waiver that would allow it to continue sending 40% of its effluent into the ocean without secondary treatment, a system that uses biological processes to virtually eliminate solids.
About 60% of the effluent from the Carson plant already receives secondary treatment. The rest is given primary treatment, a less intensive method of removing solids involving screening and the use of chemicals.
Environmentalists support full secondary treatment because solids, particles that remain in the effluent, can act as carriers for pollutants such as grease and heavy metals.
The federal Environmental Protection Agency expects to issue a tentative ruling on the districts' request within the next two months, EPA officials say. Sanitation officials say that implementing full secondary treatment would carry a $350-million price tag for their two dozen districts, which serve an array of communities from Palos Verdes Estates to Pomona.
In seeking a waiver, sanitation officials argue mainly that effluent from the Carson plant now receives sufficient treatment to ensure that it won't harm marine life in and around Santa Monica Bay. But the officials point to DDT deposits as the most pressing reason for a waiver.
An estimated 1,800 tons of DDT were discharged through the Carson plant outfalls in the 1950s and '60s, and 200 tons of it are believed to be embedded in a 13.5-square-mile area of ocean bottom off the Palos Verdes Peninsula.
The chemical was contained in sewage pumped from the now-defunct Montrose Chemical Corp. plant in Harbor Gateway, once the country's primary source of the highly toxic pesticide. The pollution was linked to high levels of DDT found in local fish and has been blamed for reproductive problems that nearly wiped out the California brown pelican in the 1970s.
Citing data from drilling samples they have gathered off the Palos Verdes Peninsula, sanitation officials say the sediment with the highest concentrations of DDT lies six to 18 inches beneath the ocean bottom. The main reason it is covered, they argue, is the accumulation of solids from the Carson plant outfalls. If the plant has to go to full secondary treatment and solids no longer accumulate, they warn, currents, tides and storm turbulence will eventually expose DDT-tainted bay sediments, contaminating bottom-dwelling organisms and the fish that eat them.
"What we're saying is that once (the DDT) gets loose, we won't know how to control it," said Charles Carry, chief engineer and general manager for the Los Angeles County Sanitation Districts. "How can we take a chance with DDT? . . . We think the data shows clearly that it's our solids that are covering it up."
Environmentalists aren't convinced that the DDT off the peninsula poses an immediate threat. They argue that the chemical may be covered sufficiently to ensure that it won't poison the marine food chain. They also suggest that natural sedimentation, rather than deposits from the outfalls, may be responsible for burying the deposits.
In any case, they say, the DDT problem is being studied as part of the federally funded Santa Monica Bay Restoration Project. If there's a danger, the county could consider other solutions besides continued pumping of solids from the Carson sewage treatment plant.
State Assemblyman Tom Hayden (D-West Los Angeles), a longtime advocate of tighter standards for ocean dumping, angrily accuses sanitation officials of fueling fears of DDT contamination to avoid complying with federal clean water standards.