EPA Superfund Site

HAMILTON/LABREE ROADS GW CONTAMINATION

WA | EPA ID WASFN1002174

About this site’s exposure pathways: As of October 2024, the Hamilton/Labree Groundwater Contamination Superfund site is considered “Insufficient Data to Determine Human Exposure Control Status” (HEID) because of a newly identified exposure pathway. Recent soil vapor gas sampling data shows tetrachloroethylene (PCE) (530 μg/m3) and trichloroethylene (TCE) (39 μg/m3) above soil vapor screening levels (Model Toxics Control Act Regulation Chapter 173-340 WAC Cleanup Levels and Risk Calculation Soil Gas Screening Level Method B Cancer) in operable unit (OU) 2 (PCE: 320 μg/m3; TCE: 11 μg/m3). The site was previously categorized as “Human Exposure Not Controlled” due to a chlorinated solvents plume in an area where many households still obtain their drinking and household use water from private wells. To date, no site contamination has been found in these private wells and the plume is now delineated. The planned activities to address this potential exposure pathway include indoor air testing and completing the human health risk assessment. EPA continues to monitor groundwater among downgradient residents who may be at risk. EPA currently anticipates having sufficient data to make a determination by September 2025, when the human health risk assessment is complete. Institutional controls are required as part of the OU1 interim remedial action and will be implemented as part of the site-wide final remedy.

In addition, EPA is currently working through property access issues to complete the indoor air sampling. In September 2024, EPA sent out a fact sheet to all residents in the community to update them on the site status.