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Palos Verdes Shelf

Cleaning up the Palos Verdes Shelf Quick Finder
Reports

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On December 19, 2000, the U.S. Department of Justice (representing the EPA and several natural resource trustee agencies) and the California Attorney General announced a $73 million settlement with Montrose Chemical Corporation of California, Aventis CropScience USA Inc., Chris-Craft Industries Inc., and Atkemix Thirty-Seven Inc., companies which either owned or operated DDT-manufacturing plants in Los Angeles County.

Along with the prior settlements in this case, there will be approximately $140 million that can be used by federal and state agencies to help rehabilitate natural resources and clean up DDT contamination on the offshore Palos Verdes Shelf. The EPA's pilot cleanup project is already underway. Department of Justice News Release Exiting EPA (disclaimer)

August 6, 2007 Update

May 2005 Update (PDF) (6 pp, 408K): Updates on EPA's activities on the Palos Verdes Shelf Institutional Controls Program and Remedial Investigation/Feasibility Study.

Summer 2004 Update: EPA initiates marketplace fish monitoring program to assess whether contaminated white croakers are reaching consumers.

EPA conducts additional field studies on Palos Verdes Shelf and collects ocean fish for sampling.

Background

Map showing location of contaminated ocean sediment in relation to the Palos Verdes Peninsula, the Montrose Chemical Plant, and the Los Angeles County Sanitation District sewer outfalls.

Palos Verdes Shelf Map (click image for larger version)

From 1947 to 1983, Montrose Chemical Corporation manufactured DDT at its plant near Torrance, California. The plant discharged wastewater containing the now-banned pesticide into Los Angeles sewers that emptied into the Pacific Ocean off White Point on the Palos Verdes Shelf (PVS). The DDT manufacturing process also resulted in groundwater and surface soil contamination on and near the Montrose plant property.

It is estimated that over 1,700 tons of DDT were discharged between the late 1950s and the early 1970s. Several other industries also discharged PCBs into the Los Angeles sewer system that ended up on the PVS by way of outfall pipes. The PVS site is defined by the large area of DDT- and PCB-contaminated sediment on the ocean floor in the vicinity of the Palos Verdes peninsula, near Los Angeles, California.

In its 1994 report, the U.S. Geological Survey (USGS) characterized an area of 44 km2 (17 sq. miles) on the PVS with elevated levels of DDT and PCBs in surface sediments. Subsequent data showed that the effluent-affected DDT- and PCB- contaminated sediments covered a larger area, and EPA expanded the PVS study area to include sediments from Point Fermin in the southeast to the southern edge of the Redondo canyon, northwest of the Palos Verdes peninsula. EPA's evaluation of potential cleanup actions is focusing on the areas of highest contamination.

Ecological and Health Risks

Image of complex marine food web, including microorganisms, bottom-feeding fish, marine animals, birds, and humans fishing.

Illustration of how DDT may move from ocean floor sediment up through the food web (click image for larger version)

High levels of DDT and PCBs continue to threaten the Palos Verdes Shelf marine environment. DDT and PCBs move from contaminated sediments into the water. They also enter the food chain through worms and microorganisms, which may be consumed by other marine life. DDT and PCBs accumulate in fish tissue, then harming fish-eating birds, marine mammals, and birds of prey that feed on both.

For people, eating DDT- and PCB-contaminated fish can increase cancer risks, harm the liver, and affect the central nervous system. Nursing infants whose mothers regularly consume the fish are also at high risk.

Historically, the waters of the Palos Verdes Shelf have been used extensively by both sport and commercial fishers. Sport anglers fish from boats and beaches in the area. The waters are also used for swimming, windsurfing, surfing, scuba diving, snorkeling and shellfishing.

Graphic illustration of DDT concentration in the sediment of the ocean floor.

Peak Total DDT in Sediment of the Palos Verdes Shelf (click image for larger version)

Since 1985, fish consumption advisories and health warnings have been posted in southern California because of elevated DDT and PCB levels. Bottom-feeding fish are particularly at risk for high contamination levels. Consumption of white croaker (also known as kingfish or tomcod), which has the highest contamination levels, should be avoided. Consumption of other bottom-feeding fish, including kelp bass, rockfish, queenfish, black croaker, sheepshead, surfperches, and sculpin, should be limited.

Cleanup Approaches

In 1996, EPA initiated a Superfund non-time critical removal action to evaluate the need and feasibility for actions to address human health and ecological risks. The non-time critical removal action later resulted in the PVS Institutional Controls Program. See the timeline page to track removal actions and associated activites.

In August 2000, EPA initiated a pilot capping project in which they placed clean sediment over a small area (1%) of the contaminated ocean floor. This pilot project provided an opportunity to evaluate cap placement methods and construction related impacts. In 2002, EPA concluded that cap construction would be technically feasible. Collected data will be used to decide if a full-scale capping project should be implemented. Currently, EPA is conducting several data gap studies to better understand the sediment fate and transport and the stability of the cap. Once these data gap studies are completed, EPA will go forward with the Remedial Investigation and Feasibility Studies (RI/FS) to evaluate cleanup options to address long term risks associated with the site.

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