Chemical Sales Co. covers five square miles in Denver, Colorado, where bulk chemicals were stored and repackaged starting in 1962. Contaminated groundwater was discovered in the South Adams County Water Supply District in 1981, and EPA identified the site as the main source. The site was added to the Superfund National Priorities List in August 1990. Today, 57 businesses operate there, employing 805 people and generating about $273.1 million in annual sales.
The main contaminants are chlorinated solvents found in groundwater and soil. These include trichloroethene, tetrachloroethene, 1,1,1-trichloroethane, 1,1-dichloroethane, 1,1-dichloroethene, 1,2-dichloroethene, vinyl chloride, benzene, dichloromethane, and carbon tetrachloride. The site is divided into four operable units covering the source area, a groundwater plume, residential wells in Alluville, and a separate well area.
Major cleanup actions include connecting over 400 residences to municipal water between 1986 and 1995, building the Klein Treatment Plant in 1989, removing leaking drums, and treating contaminated soil and groundwater using soil vapor extraction and air sparging. In 2007, In-Situ Chemical Oxidation was added to break down contaminants in the source area by injecting chemicals directly into the ground. Physical construction of the cleanup is now complete across the entire site.
The 2022 five-year review found all four operable units protective in the short term. However, it flagged 1,4-dioxane, an emerging contaminant, as a concern needing further work to ensure long-term protectiveness. EPA and the Colorado Department of Public Health and Environment (CDPHE) are running a pilot study to identify the best technology before finalizing next steps. A long-term response action is estimated to run through late 2027, and additional investigation work is expected to wrap up between June and August 2028. The next five-year review is estimated for March to May 2027. Human exposure and groundwater migration are currently under control, but the site has not yet achieved sitewide ready-for-anticipated-use status.
Community members with questions can contact the EPA Remedial Project Manager. For state-related questions, contact CDPHE. Site documents are available at the Colorado Department of Public Health and Environment HMWMD Records Center at 4300 Cherry Creek Drive South, Denver, and at the EPA Superfund Records Center at 1595 Wynkoop Street, Denver.
