(Beyond Pesticides, July 2, 2009) The EPA has just finished up with a round of public hearings on a proposed plan to cap a part of the Palos Verdes Superfund Site. This 17 square mile area of ocean floor off the Southern coast of California is home to one of the largest deposits of DDT in the U.S. Despite the fact that this chemical has been banned in the U.S. for almost four decades, there is an approximate 110 tons of DDT in the sediment of the Palos Verdes Shelf.
Concentrations of DDT and PCBs in fish continue to pose a threat to human health and the natural environment including the discovery of highly contaminated fish. In addition, a surge of additional problems with the lingering effects of DDT have risen in recent years, particularly with its buildup in our waterways. It has currently been identified as a threat to the Columbia River, as well as to the arctic. It has also been linked to a plethora of health concerns, including breast cancer, diabetes, non Hodgkin lymphoma, and autism.
Most of the contamination of the Palos Verdes Shelf is attributed to The Montrose Chemical Corporation of California. At one time this was the nation’s largest manufacturer of DDT, and it operated a plant near Torrance, California. Between the years of 1947 to 1971 the company has been charged of releasing over 1,700 tons of DDT into the LA sewer system which discharges into the Pacific Ocean from White Point. During this time, several other companies discharged PCBs into this sewer system leading to further chemical contamination of the sediment and causing serious environmental and health problems in the region.
In order to help combat this problem, the Montrose firm (which no longer operates) along with Aventis CropScience USA Inc., Chris-Craft Industries Inc., and Atkemix Thirty-Seven Inc., agreed to pay a total of $73 million towards restoration of the Palos Verdes Shelf in 2000 in a settlement with the US Department of Justice and the California Attorney General. Each of these companies either owned or operated DDT plants in LA County.
With this money, the EPA is proposing four different alternative plans and is urging the public to submit comments by July 15th 2009. The different plans are:
* Alternative 1: the “no action” alternative
* Alternative 2: institutional controls and monitored natural recovery
* Alternative 3: institutional controls, monitored natural recovery, and small cap
* Alternative 4: institutional controls, monitored natural recovery, and large cap
The EPA’s preferred plan is number 3, with institutional controls, monitored natural recovery and small cap. This cap would be an 18-inch layer of clean sand and coarse silt to cover about 320 acres of the shelf and approximately 36.5 metric tons of DDT. Alternative 4, on the other hand, would cap approximately 640 acres under an 18-inch layer of clean sand and silt, covering an estimated 54.4 metric tons of DDT. Under alternative 3, a surface water quality goal of 0.22 ng/L would be reached by 2023 while under alternative 4, it would be reached in 2019. A sediment cleanup level of 230 Î¼g/kg DDT under alternative 3 would be reached by approximately 2039, whereas under alternative 4, it would be reached by 2031. Furthermore, under alternative 4, the PCB sediment cleanup level o f 7 mg/kg PCBs OC would be immediately met for the shelf, but not the slope of the Palos Verdes Shelf, according to the EPA, whereas PCB sediment level has not been determined for alternative 3.
The cap obviously does not clean the area, but would work by physically containing an area of the shelf in order to prevent erosion of the contaminated sediment, preventing dissolved contaminants from the sediments from flowing into the water, and by reducing the exposure of contaminants to benthic with a clean layer of sediment. Some of the reasons that the EPA states for favoring alternative 3 over 4, despite the fact that it would be more efficient and longer lasting, is because the smaller cap will cause less disruption of sediment and benthic organism habitat. It will also cost less and be less difficult to implement, overall.
If you’d like to express your opinions or concerns to the EPA regarding their cap plan, The EPA will accept written comments until July 15, 2009. These can be sent to: C.R. White (SFD-8-2) U.S. EPA, Region IX75 Hawthorne Street, San Francisco, CA 94105.