The Department of Toxic Substances Control (DTSC) approved The Arroyo at Monrovia Removal Action Workplan (RAW). The RAW identified elevated concentrations of Chemicals of Concern in soil vapor that pose a potential health risk to future occupants of the new mixed-use residential and commercial building from vapor intrusion.
To address Tetrachloroethylene, Trichloroethylene, and heavy metals the following remedial actions will be implemented:
• Installation of a Soil Vapor Extraction (SVE) system to extract Chemicals of Concern from unsaturated soil. The SVE system will consist of an extraction well network, soil vapor treatment system, trenched conveyance lines, blower, and monitoring network.
• Limited Shallow Soil Excavation – Excavate approximately 465 cubic yards of dieldrin, and toxaphene impacted soil from the property located at 230 W. Evergreen Avenue.
• Institutional Controls (IC) - ICs will consist of a Land Use Covenant that includes a soil management plan for shallow soil disturbed at the Site, as well as a requirement, where necessary, of appropriate engineering controls, such as a Vapor Intrusion Mitigation System, for the protection of residents and workers within future buildings that may be constructed on the Site.