The United Heckathorn Superfund site is located in Richmond Harbor, an inlet of San Francisco Bay, in Contra Costa County, CA. It includes five acres of land and about 15 acres of marine sediments in two channels (Lauritzen and Parr) of Richmond Harbor. From 1947 through 1966, several companies, including R.J. Prentiss, Heckathorn and Company, United Heckathorn, United Chemetrics, and Chemwest Inc. used the site to formulate, package, and ship pesticides. No chemicals were manufactured on site. Heckathorn would receive technical grade pesticides from chemical manufacturers, grind them in air mills, mix them with other ingredients such as clays or solvents, and package them for final use in liquid or powder form. Although many pesticides were handled at United Heckathorn, dichlorodiphenyl trichloroethane (DDT) accounted for approximately 95 percent of Heckathorn's operations. United Heckathorn went bankrupt in 1966. By 1970, the facility buildings had been demolished and cleared from the site.

During United Heckathorn's operation, regulatory agencies occasionally inspected the facility. During a site visit in 1960, the Bay Area Regional Water Quality Control Board observed bulk storage of pesticides and solvents, leaking solvent pump lines, spills, and waste discharges. Subsequently, the California Department of Fish and Game discovered dead fish in the Lauritzen Channel and, on a separate inspection, it observed a milky liquid emanating from the site into the Lauritzen Channel. In 1980, the California Department of Health Services inspected and sampled the site as part of the Abandoned Site Project. Chlorinated pesticides and metals were detected in soil samples, and the area was designated a State Superfund site in March 1982. In March 1990, U.S. EPA placed the site on the National Priorities List.