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• 'V vP9 • San Joaquin CountyP Page 4 Environmental Health Department June 9, 2008 Project Number 99008-008073.03 • If groundwater is slow to enter the borehole, Bureau Veritas will install a temporary, one-inch- diameter, slotted-screen, schedule 40 PVC casing into the open borehole approximately 2 to 4 feet below first encountered groundwater. A peristaltic pump with new polyethylene tubing or single-use disposable bailers will be used to obtain the grab-groundwater samples (if encountered). Upon retrieval, the grab-groundwater samples will be transferred directly into appropriate sample containers provided by the analytical laboratory. The grab- groundwater samples will be sealed, labeled and placed in a pre-chilled ice chest for delivery to the laboratory. Chain-of-custody records will be completed and accompany the grab-groundwater sample shipments to the laboratory. After completion of soil and groundwater sampling, the borings will be sealed with grout, a mix of water and Portland Type 1/11 cement from the base of the boring to the surface. Soil Vapor Sampling Bureau Veritas proposes to collect soil vapor samples from three shallow borings BV-1 SV, BV-2SV and BV-3SV) at the same general locations as Borings BV-1 through BV-3 that will be advanced using direct push equipment to a total depth of about 5 feet bgs. Upon completion of the borings, active soil vapor samples are proposed to be collected by installing a soil vapor probe at the base of each boring and filling the annual space with about one-half foot of clean sand. The remainder of the boring will be filled with bentonite pellets, the pellets in the upper 4 feet of the boring will be hydrated to seal the boring so that ambient air does not enter the boring. The soil vapor sampling will be conducted in accordance with the guidance provided in the Regional Water Quality Control Board (RWQCB) Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater(RWQCB, 2005), California Department of Toxic Substances Control/Los Angeles RWQCB Advisory—Active Soil Gas Investigations (DTSC/LARWQCB, 2003), and DTSC's Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air(DTSC, 2005). After completion of vapor sampling, the probe tubing will be removed from the boring. Decontamination and Waste Generation Drilling equipment and down-hole sampling equipment will be steam cleaned or washed in a solution of non-phosphate detergent, double rinsed with tap water after each use, and allowed to dry. Rinse water and soil drilling cuttings will be containerized in 5-gallon plastic buckets or Department of Transportation (DOT) approved 55-gallon drums. The wastes will be sealed and labeled with the appropriate generator information and temporarily stored onsite for future disposal pending receipt of analytical results. Upon completion of sample collection, each borehole will be sealed in accordance with an approved SJCEHD method. Task 3: Analytical Testing Bureau Veritas proposes to submit a total of up to 3 soil, 3 grab-groundwater, and 3 soil vapor samples for chemical analysis for this investigation. The collected samples are proposed to be analyzed using one or more of the following USEPA Methods: Soil Samples—(Three) • VOCs by Method 8260B • TPH by Method 8015M One soil sample will be submitted for chemical analysis of VOCs from each boring based upon field PID headspace screening, soil recovery and physical observations. Should no field evidence of soil contamination be encountered during the collection of soil samples, Bureau Veritas proposes to submit S:\ESTROJECTS%3-Chicago X991(75-76)@008108073 StocktonThase 2\080447 Wkplan SJCo.eoc