Watkins Johnson Co Stewart Division Plant

⚠ Superfund · Construction complete

Construction of all remedies is complete. Pumping and treating contaminated groundwater reduced the size of the plume and the threats posed to the nearby population. The soil vapor extraction and treatment system reduced concentrations of volatile organic compounds (VOCs) in the soil so that they no longer present a threat to the groundwater.

Location

CityScotts Valley
CountySanta Cruz County
StateCalifornia
Coordinates37.05111, -122.02903

Contaminants of concern

Contaminated media

Cleanup timeline

  1. Initial Assessment Completed — 10/01/1985
  2. Proposed to the National Priorities List — 01/22/1987
  3. Finalized on the National Priorities List — 08/30/1990
  4. Remedial Investigation Started — 09/22/1987
  5. Final Remedy Selected — 06/29/1990
  6. Final Remedial Action Started — 12/16/1991
  7. Construction Completed — 09/22/1994
  8. Deleted from National Priorities List — Not Yet Achieved
  9. Most Recent Five-Year Review — 09/09/2022
  10. Achieved Sitewide Ready for Anticipated Reuse — Not Yet Achieved

EPA references

EPA-regulated facilities nearby

Understanding this Superfund site

Watkins Johnson Co Stewart Division Plant is a federal Superfund site in California. The Superfund program, created by Congress in 1980, addresses sites where hazardous substances have been released or threaten release into the environment. EPA scores potential sites using the Hazard Ranking System; those that score high enough are placed on the National Priorities List.

Current status: Construction complete. Physical construction of the cleanup remedy is complete, though long-term monitoring and institutional controls typically continue for years or decades. Groundwater treatment systems, for example, often run long after surface cleanup finishes.

EPA has identified 10 contaminants of concern at this site, including 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1-dichloroethane. Contamination has been detected in soil, groundwater.

If you live near this site and have health concerns, your state health department can provide site-specific guidance. EPA maintains a community involvement program for most NPL sites, and site documents — including the Record of Decision, five-year reviews, and public health assessments — are typically available through EPA's Superfund site profile.