Valley Wood Preserving, Inc. is a former wood preserving facility in Turlock, California, listed on the National Priorities List (NPL) in 1989. The EPA divided cleanup into three operable units covering soils, groundwater, and sitewide coordination. Physical construction of the cleanup wrapped up in August 2008, and the site was deemed ready for anticipated reuse in March 2010. The site has not yet been deleted from the NPL.
The facility contaminated soil, groundwater, and leachate with a range of chemicals. Confirmed contaminants include arsenic, arsenic compounds, chromium, chromium(VI), copper, manganese, and sulfur. Hexavalent chromium and arsenic are the primary drivers of ongoing concern. The main health risks involved people ingesting or coming into contact with contaminated soil or groundwater.
Cleanup began with emergency excavation of roughly 1,500 cubic yards of contaminated soil and the extraction and treatment of 70 million gallons of chromium-contaminated groundwater between 1979 and 1983. Over time, active extraction gave way to in-place treatment and monitored natural attenuation, a process where natural conditions gradually reduce contaminant levels without direct intervention. Soil cleanup actions are fully complete. Low levels of hexavalent chromium and arsenic remain in groundwater above cleanup goals.
Recent investigations in 2020, 2022, and 2023 identified previously unaddressed areas of groundwater contamination. A pilot test in 2024 was conducted to design full-scale remediation of remaining contamination. The EPA's September 2024 Five-Year Review found the remedy currently protective of human health and the environment. Human exposure is under control and groundwater migration is stabilized with no unacceptable discharge to surface water. The review did flag concerns, including a newly characterized chromium plume in the southwest portion of the site, possible shifts in groundwater flow direction, and residual soil contamination that may still be affecting groundwater. The EPA recommended expanding the monitoring well network, increasing sampling frequency, investigating potential contamination at an adjacent property, and ensuring the landowner follows land use restrictions that limit the site to industrial use only.
Community members and interested parties with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager.
