Western Processing Company operated in Kent, Washington from the 1960s until 1983, accepting industrial wastes from about 300 businesses. Those wastes included electroplating waste, acids, pesticides, spent solvents, waste oils, and transformers. The company stored materials in bulk tanks, drums, and lagoons, contaminating soil, groundwater, and sediment. EPA closed the site by court order in April 1983 and added it to the National Priorities List on September 8, 1983.
Cleanup is organized into separate work areas. The first, Operable Unit 1, addressed surface contamination through excavation and off-site disposal of hazardous materials, plus removal of buildings and tanks. The second, Operable Unit 2, targets site-wide soils and groundwater using a slurry wall built in 1988, along with groundwater extraction and treatment systems and a cap placed over the main containment area in 1999. A third effort cleaned up sediment in Mill Creek and the East Drain between 1993 and 1995. In total, the emergency removal phase extracted over 1.9 million cubic yards of solids and 930,000 gallons of hazardous liquids.
EPA has identified 51 contaminants of concern at the site. These include volatile organic compounds (VOCs) such as trichloroethene, tetrachloroethene, benzene, and chloroform; heavy metals including lead, cadmium, chromium, nickel, copper, and zinc; polycyclic aromatic hydrocarbons (PAHs) like naphthalene and pyrene; and pesticides, cyanide, petroleum, and polychlorinated biphenyls (PCBs). Contamination is present in soil, groundwater, and building structures. The greatest health risks come from drinking contaminated groundwater and direct contact with sediment.
The cleanup is performing well. Pumping and treatment rates have decreased over time, and contamination remains contained within the slurry wall and cap. Groundwater in the off-site plume has biodegraded to below cleanup standards. Federal cleanup standards for surface water in Mill Creek and East Drain have been met. EPA's assessment confirms that human exposure is currently under control across the entire site and that contaminated groundwater migration is stabilized. The site has not yet been deleted from the National Priorities List, and restrictive covenants required by the Record of Decision have not yet been implemented in one portion of the site. The most recent five-year review was completed on September 11, 2023, with the next review estimated between September and November 2028.
Community members with questions can contact the Community Involvement Coordinator. For technical questions, contact the Remedial Project Manager. Site documents are available at Kent Regional Library at 212 2nd Avenue N. in Kent and at EPA Region 10's Superfund Records Center at 1200 Sixth Ave., Suite 155 in Seattle.
