The Selma Treating Co. site covers 18 acres in Selma, California, where a wood treatment facility operated from 1936 to 1981. The EPA added it to the National Priorities List in September 1983. Cleanup began in 1988 and has moved through multiple phases, organized into operable units for soil and groundwater. One on-site business was operating as of December 2024, employing five people and generating about $1,030,000 in annual sales.
Thirteen contaminants of concern have been identified in soil and groundwater. These include hexavalent chromium, arsenic, copper, and pentachlorophenol in both media. Soil also contains bis(2-ethylhexyl)phthalate, dibutyl phthalate, trichlorophenol, and chlorinated dioxins and furans. Groundwater contains chlorinated dioxins and furans as well. Hexavalent chromium is the primary concern. California set a drinking water standard of 10 micrograms per liter for hexavalent chromium in 2014, but that standard was no longer in effect as of September 2017 while the state reevaluated the level. The EPA continues using the former 10 microgram per liter standard in its review work.
Soil cleanup is complete. Work included excavating contaminated material, stabilizing and storing excavated soil, installing asphalt and vegetative caps, and sealing six dry wells. A groundwater extraction and treatment system ran from 1998 until 2005, when the remedy shifted to in-situ bioremediation. That process injects molasses into groundwater wells to feed naturally occurring bacteria, which convert hexavalent chromium into a less mobile and less soluble form. The California Department of Toxic Substances Control now operates the bioremediation system. A sitewide removal action was completed between August and September 2018. Construction overall finished in January 2005, and the site was designated ready for anticipated reuse in June 2006.
Human exposure to contamination is currently under control, meaning no unacceptable exposure pathways exist. However, groundwater migration is not under control. Contaminated groundwater continues to move, and the EPA is investigating hexavalent chromium contamination that extends south of the former facility and Highway 99. Ongoing work includes sampling private groundwater wells, providing alternative drinking water if needed, and installing new monitoring wells. The most recent five-year review was conducted in September 2021. The sixth five-year review is underway, with a final report due by September 30, 2026.
Community members can access site records at the Selma Branch of the Fresno County Library at 2200 Selma Street in Selma, California. The EPA's Superfund Records Center in San Francisco can be reached at 415-947-8717. The completed five-year review report will also be posted online. For direct questions, the EPA has designated contacts for both community involvement and remedial project management.
