ARCHIVED REPORTS_VAPOR INTRUSION SURVEY - SOIL GAS SAMPLING REPORT

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' 2.0 SOIL GAS SAMPLING INVESTIGATION PSC submitted the Vapor Intrusion Survey — Soil Gas Sampling Work Plan (Work Plan) on ' September 30, 2008 in accordance with the August 15, 2008 CVRWQCB request. The CVRWQCB approved the Work Plan in a letter dated October 2, 2008. A copy of the regulatory correspondence is presented in Appendix A. The Work Plan involved the ' installation of temporary soil gas sampling points at the Site to evaluate whether soil vapor intrusion may be a concern to the quality of the ambient breathing air inside the building present on-site. PSC proposed to collect seven soil gas samples plus a test sample at the Site ' via the temporary direct-push sampling method. The field activities were performed on January 30, 2009. The soil gas sampling and analyses were in general accordance with the Vapor Intrusion Pathway: A Practical Guideline issued by the Interstate Technology & Regulatory Council (ITRC) (ITRC, 2007), and the Advisory-Active Soil Gas Investigations issued by the California Department of Toxic Substances Control (DTSC) and Los Angeles Regional Water Quality Control Board (LARWQCB), (DTSC and LARWQCB, 2003). ' The eight soil gas sample locations were identified as SG-Test and SG-1 through SG-7. The first soil gas sampling point (SG-Test) was located within the former UST excavation approximately 15 feet from the west wall of the building. The first soil gas sampling point to be submitted for analysis (SG-1) was located within the former UST excavation approximately five feet from the west wall of the building. The second was centrally located inside the building near MW-4A. Three of the five remaining points were located (on approximate 40-foot centers) from the building's northwest comer towards the east along the building's north wall. The last two points were centered on the west and east end of the ' building. All exterior locations were located approximately five feet from the building wall. The completed locations are depicted on Figures 3 and 4. The following sections describe the field activity procedures and results of the investigation. ' 2.1 Pre-Field Procedures PSC completed the San Joaquin County Environmental Health Department (SJCEHD) boring t permit application to perform the soil gas sampling activities. The boring permit application was submitted on January 20, 2009. The SJCEHD approved the permit on January 22, 2009. A copy of the approved SJCEHD boring permit is presented in Appendix B. ' PSC coordinated the field schedule with the property owner to obtain site access to perform the sampling. PSC then obtained and coordinated schedules with coring and drilling ' subcontractors to perform the various related tasks. PSC prepared a Health and Safety Plan (HASP) for PSC personnel and their subcontractors ' performing on-site field activities. All personnel were informed of the health and safety concerns regarding the work to be performed and the Site conditions. Daily safety meetings were held prior to starting field activities. A copy of the HASP is presented in Appendix C and the completed signature pages of the HASP are presented in Appendix D. Upon SJCEHD permit approval, PSC coordinated with Subdynamic Utility Detection ' Services, Inc. (SubDynamic) to perform the third party utility location clearance. PSC Vapor In anion Survey Soil Gas Sampling Report ' Prepared For:Sere Lee Bakery Group,Inc. Prepared By:PSC Industrial Outsourcing,LP Sats Lee—Lincoln Street\2009_03_31-Soil Gas Sampling Repon.doc March 31,2009 6