The Montrose Superfund site is approximately 13 acres in area, and is situated directly adjacent (west) to the former Del Amo facility. According to a Works Progress Administration land use map from 1937, the Montrose site was already used for chemical manufacturing, while the adjacent Del Amo site was virtually untouched cropland and pasture. EPA records do not specify any operations or land use at the Montrose site back in 1937, so it is unknown exactly what sort of chemical manufacturing took place during this time or which company owned the site. (This information would be extremely valuable in piecing together even earlier activities at the site for historical purposes.)
Montrose Chemical Corporation was one of the only companies in the US that manufactured the pesticide DDT (dichloro-diphenyl-trichloroethane). DDT production at the site occurred from 1947 to 1982 (EPA 2015). Operations at the plant included manufacturing, packaging, and distributing DDT internationally. After DDT was banned in the US in 1972, Montrose continued to manufacture and ship the pesticide and operated the plant until 1982, at which time the company permanently closed and dismantled (EPA 2015). As a temporary measure to prevent DDT from surface soils to disperse via wind or storm water, Montrose re-graded and paved the majority of the plant in 1985. Currently the Montrose property is undeveloped and unoccupied (EPA 2015). In 1984 the Montrose site was proposed for the NPL and was listed in 1989 as a Superfund site.
According to the EPA, the Montrose plant operated continuously 24 hours a day, 7 days a week, manufacturing DDT for a total of 35 years. It is estimated that during this time, 1.6 billion pounds of DDT was produced (EPA 2001). Throughout Montrose site operations and at least up until 1953, releases of DDT in storm water runoff flowed into natural drainage paths originating at the southeast corner of the property as a result of sewer line blockages from the Montrose site. Runoff material included acidic waste waters and by-products of DDT such as chlorobenzene and chloral. Portions of the storm water pathway included the Jones Ditch and Normandie Avenue Ditch (immediately south, down gradient to the site), as well as the unimproved Kenwood Ditch, which ran along the western-most boundary of Kenwood Avenue (formerly Florence Avenue) beginning at 204th Street (formerly Maple Street) to the north, and ending at Torrance Blvd to the south. Waste waters which entered the Kenwood Ditch ponded in various locations along the ditch since these were the lowest-lying areas. EPA estimates that approximately 156,000 to 233,000 gallons of waste waters were discharged per day in the storm water pathway during any occurrence of sewage blockages at Montrose.
The contamination resulting from the Montrose Chemical Corporation DDT operations was/is substantial, far more so than the Del Amo site operations alone. DDT and DDT by-products persist in soil, do not dissolve easily in water, and accumulate in the fat cells of animals and humans. The scope of the contamination from Montrose can be traced to the drainage outlets such as White’s Point outfall (sanitary sewer) off the Palos Verdes Peninsula, on the Palos Verdes Shelf, along areas of the Torrance Lateral (open channel), Dominguez Channel, and the Consolidated Slip, where the Dominguez Channel empties into the Los Angeles and Long Beach Harbors. The reason that Montrose is indisputably responsible for the DDT contamination found in these areas is because it was the only company that manufactured the pesticide in California (and the only company to operate after the national ban of DDT in the US) and exposure pathways (drainage) are directly linked back to the facility.