South Wilbur petroleum contamination site

Ecology visited the site on May 1, 2025, and found monitoring wells and fencing in good condition. No changes were made to the ground surfaces, buildings, or site use that would potentially expose people or animals to remaining contamination. The environmental covenant remains in place to document remaining contamination and prevent exposure.

We also reviewed groundwater monitoring data collected from 2018 through 2025, and evaluated groundwater trends for all data collected since 2006. Gasoline and benzene are still above cleanup levels. Trends are mostly stable or improving, with one well showing increases in contamination. Diesel, toluene, ethylbenzene, and xylene have met cleanup levels and will no longer be monitored.

Learn more

• Review the draft periodic review.
• Visit our South Wilbur petroleum contamination site page.

Next steps

Ecology will review all comments received during the comment period and update the periodic review if needed. If no significant changes are made, the periodic revi​​ew will become final. If significant changes are made, an additional public comment period will be held. We will hold a public meeting if 10 or more people request one.​​​

Site history

The site includes three properties, two government maintenance facilities and a fueling station, which all contributed to petroleum contamination in soil and groundwater.

Contaminated soil was removed from three areas in 2005, and then an oxygen-releasing compound was mixed with clean backfill and placed in the excavated areas to help reduce groundwater contamination. Based on recommendations from the first periodic review, another groundwater treatment was tested in 2013 that was able to reach contamination under buildings.

About periodic reviews

We conduct a periodic review at least every five years after beginning cleanup at a site, and this is the third review for this site. The purpose of the review is to evaluate current site conditions and to ensure the continued protection of people and the environment.