Vapor Mitigation - Industrial Facility

Elevated concentrations of trichloroethene (TCE) were identified in shallow groundwater under the floor slab of a building near a downtown Seattle industrial facility where Farallon was conducting a remedial investigation. Results of an indoor air assessment conducted to evaluate the health risk to workers in the building indicated that TCE was present in a portion of the building at concentrations exceeding appropriate action levels. Farallon worked together with the property owner and building tenants in designing a subslab depressurization system that would effectively mitigate vapor intrusion health risks in the affected portion of the building. Upon Ecology approval of the Vapor Intrusion Mitigation Work Plan and the Vapor Intrusion Mitigation Design Plan prepared by Farallon, the subslab depressurization system was installed. Farallon’s ongoing involvement in this project includes operational maintenance of the mitigation system, continuing communication with building tenants, and regular monitoring of shallow groundwater and indoor air to ensure that health risks to building tenants continue to be effectively mitigated. The system will remain in operation until TCE concentrations in shallow groundwater and indoor air have been confirmed to be below appropriate action levels.