The California Department of Toxic Substances Control (DTSC) determined a cleanup action was required to address soil gas contamination from the release of chlorinated volatile organic compounds (CVOCs) beneath the GBS Linens Facility (GBS Sile). The cleanup decision document, referred to as Removal Action Workplan (RAW), summarized the evaluation of remedial alternatives and concluded remediation consisting of a shallow Soil Vapor Extraction (SVE) system was required to protect human health and the environment. DTSC approved the RAW, prepared by C2REM, dated August 2018 pursuant to Chapter 6.5, Division 4.5, Sections 25323.1 and 25356.1 of the Health and Safely Code.
Project activities consist of the installation of a sub-slab depressurization system, which will include six sub-slab SVE points, associated piping, vapor treatment system, equipment enclosure, and eight soil vapor observation points. The SVE system is designed to function by continuously creating a lower pressure underneath a building floor relative to the pressure within a building. The resulting sub-slab negative pressure prevents soil gases from flowing into the building through the floor slabs, and thus CVOC entry into the building is also reduced. During the installation of the SVE system, deeper soil vapor, samples will be collected and contingent vertical SVE wells may be installed and connected to the same vapor treatment system which will remove CVOCs from effluent air before discharging it to the atmosphere.