Watkins-Johnson Co. (Stewart Division Plant)

Overview

The Watkins-Johnson Company Stewart Division Plant is a 3-acre former industrial property in Scotts Valley, California. It has manufactured furnaces and electrical parts since 1963. The site was added to the National Priorities List (NPL) in August 1990 after improper hazardous waste handling left volatile organic compounds (VOCs) in soil and groundwater. It remains on the NPL today.

EPA identified 16 contaminants of concern at the site. These include chlorinated solvents such as trichloroethene, tetrachloroethene, 1,1,1-trichloroethane, vinyl chloride, and cis-1,2-dichloroethene, among others. Silver was also detected in groundwater. Several contaminants appear in both soil and groundwater. About 10,600 people within a three-mile radius rely entirely on groundwater for drinking water, making contamination control especially important.

Cleanup began in earnest with a remedial investigation in September 1987. A final remedy was selected in June 1990 and construction was completed in September 1994. The selected approach for the site's one operable unit included pumping and treating contaminated groundwater, capping contaminated soil, and using soil vapor extraction (SVE) to pull VOCs out of the ground. The groundwater extraction and treatment system, which ran from 1986, successfully stopped the contamination plume from spreading and has since been shut down. SVE reduced VOC concentrations to acceptable levels. Indoor air sampling in 2017 and 2018 found one vapor intrusion issue that was immediately fixed, and follow-up sampling confirmed the remedy protects building occupants. Activity and use limitations keep the property restricted to commercial and industrial uses.

EPA has completed five-year reviews in 2002, 2007, 2012, 2017, and most recently in September 2022. The agency currently considers human exposure and groundwater migration to be under control across the entire site. The potentially responsible party is now decommissioning all site wells in preparation for a sitewide "ready for anticipated use" designation. Operation and maintenance activities are ongoing through late 2027, when the next five-year review is also expected. The property owners are separately preparing a focused feasibility study that could support future residential use, though the current remedy only allows commercial and industrial activity.

Community members can stay involved through the Blue Bonnet Bean Creek Community, an active advisory group that keeps residents informed about site conditions and cleanup progress. For questions, contact the EPA Community Involvement Coordinator or the Remedial Project Manager. For state-related questions, contact the Regional Water Quality Control Board.