Contaminated soil, water and air in an unincorporated area near Torrance in Los Angeles County is a twofer for the U.S. Environmental Protection Agency (EPA), in that the agency has been doing work on two adjacent Superfund sites for decades.

The two sites are so intertwined that 1992 EPA investigations of groundwater contamination and a 1998 remedial plan were done jointly. A number of large-scale industrial companies left a toxic footprint that is still being cleaned up. The Los Angeles Times said they produced two of the worst chemical dumps in the nation.

But it wasn’t until this year that the EPA stuck air samplers in homes of the community surrounding the Del Amo Superfund and Montrose Chemical Superfund sites to see what residents were breathing. Residents were kind of curious about that because it was known that the companies had dumped trichloroethylene (TCE), benzene and chlorobenzene into open unlined pits, which subsequently leached into the groundwater and migrated into the environment.  

“The need to sample is urgent,” John Lyons, acting assistant director of the EPA's regional Superfund division, told the Times.

The EPA resisted doing the testing until breathing TCE was recently linked to higher incidents of birth defects and cancer. The groundwater contamination plume extends beneath the homes being tested for vapor intrusion from evaporation through the soil.  

The 280-acre Del Amo site was owned by the U.S. government during World War II and hosted a synthetic rubber plant and manufacturers of styrene and butadiene. It was sold to Shell Oil Co. in the 1950s. Goodyear Tire and Rubber Co., Dow Chemical Co., Shell and others dumped their wastewater sludge into six unlined pits and three unlined evaporation ponds on a four-acre disposal site from 1943 to 1972, when the facility was shut down.

At that point, any open pits and ponds were filled in with dirt. It was declared a Superfund site in 2002.

The neighboring Superfund site was once the 13-acre home of a Montrose Chemical Corp. plant that manufactured the pesticide DDT from 1947 to 1982. EPA’s Del Amo webpage notes 1984 as the date “contamination was first discovered.”

The company razed the factory and paved the ground with asphalt. The property was declared a Superfund site in 1989. In addition to befouling local groundwater, the plant dumped chemicals into the ocean from the Palos Verdes shelf.

By the 1990s, discoveries of bowling-bowl-size chunks of DDT led to the demolishment of 63 homes, according to the Times. Subsequent remediation measures to reduce contamination have been ongoing, including capping waste areas and treating soil and water.   

Ongoing monitoring of sites and surrounding areas has detected disturbing growth in TCE concentrations underneath homes.

Most of the combined site was redeveloped as an industrial park, surrounded on three sides by industrial and commercial enterprises. But there are at least 14,000 people living within a mile to the south, and 34,000 people within four miles who drink from a deep aquifer there.

–Ken Broder

To Learn More:

EPA Begins Testing Air in Homes near South Bay Superfund Sites (by Tony Barboza, Los Angeles Times)

EPA Seeks Public Input on Cleaning Heavy DDT Contamination in Harbor Gateway (by Sandy Mazza, Daily Breeze)

EPA Will Start Lengthy Construction Project to Clean Harbor Gateway Groundwater (by Zen Vuong, Torrance Daily Breeze)