EPA ID# WA0000026534
EPA Region 10
Thurston County

3rd Congressional District

Other Names:
Last Update: April, 2010

Hide details for Site DescriptionSite Description

The Palermo Well Field Groundwater Contamination site is located in a light commercial and residential area in the City of Tumwater. The site is surrounded by single family dwellings, private businesses, and recreational facilities. The Palermo Well Field consists of six water supply wells that provide up to 50% of the drinking water for the city of Tumwater. In 1993, routine sampling revealed the presence of trichloroethylene (TCE) in three of the six wells. The impacted wells were removed from service in 1993. Groundwater contamination at this site could potentially affect approximately 13,000-25,000 people.

Site Responsibility: This site is being addressed through federal actions.

NPL Listing HistoryDates
Proposed Date:12/23/1996
Removed Date:
Withdrawal Date:
Final Date:04/01/1997
Deleted Date:

Hide details for Threats and ContaminantsThreats and Contaminants

Media Affected: Soil, Surface Water & Groundwater
Groundwater and off-site surface water are contaminated with TCE and tetrachloroethylene (PCE). The source of PCE was determined to be a dry cleaning facility in the commercial area. Sources of TCE contamination include both former and current Washington Department of Transportation facilities in the commercial area. The contaminated groundwater represents a health risk to people using the aquifer as a domestic water supply. Contaminated groundwater surfacing in a residential neighborhood adjacent to the well field represents a potential health risk to people living in affected homes.

Hide details for Cleanup ProgressCleanup Progress

Early Actions: A soil vapor extraction system was installed under the dry cleaning facility in early 1998 and operated until the summer of 2000. The extraction system removed approximately 400 pounds of PCE from the soils. Construction of two air stripping towers at the city wellfield was completed in March 1999. The treatment system is removing contaminants from the groundwater to non-detectable levels and has allowed the city to use all six wells for its water supply.

Long-term Actions: EPA completed a Remedial Investigation and Feasibility Study in June 1999 and determined the final cleanup remedy for the site in November 1999. This remedy was completed in February 2001. In addition to the early actions, the final cleanup includes construction of an underground drainage system to lower the groundwater table under the affected homes. The contaminated water collected by the drainage system is treated in an aerated lagoon before discharging into an existing drainage ditch, which flows into the Deschutes River. During this project, EPA has worked to keep the community closely informed and involved, scheduling site visits, holding several public informational meetings and a public hearing, and sending out informational fact sheets. While the drain was being built, EPA staff and contractors met with the community regularly to ensure that construction went smoothly and their concerns were addressed.

EPA completed a Five-Year Review of the remedy in September 2003. The most significant outcome of the review was that the underground drainage system may not be adequately protecting all residences in the Palermo residential area and that additional assessment is needed. The main reasons for the additional assessment are new information indicating that PCE & TCE may be more toxic than previously believed and the groundwater table has not been consistently lowered as designed. EPA conducts monitoring of the air in crawlspaces of houses above TCE contaminated groundwater. EPA is assessing whether it would be more appropriate to install mitigation systems to prevent inhalation of TCE from the crawl spaces. EPA litigated against Washington Department of Transportation in 2007. The court found Washington Department of Transportation liable for the TCE contamination.

EPA conducted a Second Five-Year Review in September 2008. Based on additional isotope analysis that was used in the previously cited litigation, EPA concluded in the 2008 Five_Year Review that natural attenuation is not a significant process at the Palermo Site, which affects the restoration timeframe in the ROD. The Second Five-Year Review also suggested that a capture zone analysis be prerformed to determine whether the TCE plume is being fully captured, and to evaluate the groundwater monitoring system to assess if existing wells are adequate for monitoring plume migration and remediation. In the 2008 Five-Year Review, additional vapor intrusion monitoring was conducted, and no homes were found to exceed the remedial goal of 1.46 ug/m3. However, continued indoor air monitoring was suggested, as well as a re-evaluation of the remedial goal for the groundwater-to-indoor-air pathway.

In 2011, EPA conducted an Optimization Evaluation of the Palermo Wellfield Superfund Site. The Optimization Evaluation recommended expanding groundwater sampling to better define the plumes and to inform an updated capture-zone evaluation, as well as updating the capture-zone analysis. The Optimization Evaluation also recommended changes to the Vapor Intrustion monitoring at the site. The Optimization Evaluation recommended renewing and improving the indoor ir sampling program in the Palermo Neighborhood, installing mitigation systems if needed, and conducting a vapor assessment in the Southgate Shopping Center. Additionally, the Optimization Evaluation suggested evaulating options for lowering the water table at the bluff and throughout the Palermo neighborhood. The project team is in the process of expanding the monitoring at the site to better asses contaminant transport and potential exposures.

Hide details for Regional ContactsRegional Contacts

PHONE NUMBER:206-553-1813
PHONE NUMBER:206-553-1275
Information pertaining to this site is housed at the following location(s):
Tumwater Public Library (Administrative Records)
7023 New Market Street
Tumwater, WA 98501

EPA Region 10 Superfund Records Center (Administrative Records)
1200 Sixth Avenue, ECL-076
Seattle, WA 98101