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Wistonc UST Investigation—Work Plan County of San Joaquin 630 N.California Street,Stockton,California April 13,2011 Page 2 not detect volatile organic compounds (VO ). Based on the former use of the warehouse for storing vans and automobiles, Condor concluded that there is a high probability for a fuel UST having been in operation from the 1940s until the 1970s. An abandoned UST may still be present, possibly backfilled with concrete beneath the driveway next to the warehouse. Sufficient evidence exists to warrant evaluating soil in the vicinity of the vent pip for petroleum hydrocarbon contamination. 3.0 SOIL INVESTIGATION PLAN Three continuous core soil borings are prop sed to be advanced to a depth of approximately 30 feet bgs. Additional step-out borings may be completd if time allows. Up to 12 soil samples will be collected from the three borings at intervals with observable indications of contamination or at regular intervals. A PID will be used to screen soil samples for VOCs. A California Professional Geologist will perform the borehole geologic logging. The proposed boring locations are shown on Figure 3, Appendix A. 4.0 BORING INSTALLATION FIEL D PROCEDURES 4.1 SITE PREPARATION Condor will prepare the soil boring installation permit applications for submittal to the San Joaquin County Environmental Health Department (SJCEHD). Condor will obtain the required permits prior to initiating any fieldwork. The proposed boring locations will be marked with white paint and Underground Service Alert (USA) will be notified at least 48 hours in advance of the fieldwork to locate and identify underground utilities in and near the work area. However, because companies contacted by USA may not identify utilities past private property lines and into the Site, a private utility locator will be used. The private utility locator will also attach instrumentation to the vent pipe in order to determine whether a UST may still be present beneath the driveway. Prior to initiating fieldwork at the Site, all field personnel will familiarize themselves with the Site-Specific Health and Safety Plan (HASP). In addition, a tailgate safety meeting will be held prior to comme cement of fieldwork. The HASP pertains to field activities and includes information on potential hazards expected to be encountered at the Site, personal protective equipment, and directions to and telephone numbers for the nearest hospital. A copy of the 14ASP is included in Appendix B. 4.2 DIRECT PUSH BORING FIELD PROCEDURES The direct push borings will be hydraulically advanced using a 2-inch-diameter conical bit. The bit and associated push rods will be thoroughly cleaned before each boring is advanced using a laboratory-grade, non-phosphate detergent and deionized water and double-rinsing with deionized water. Upon completion of the borings and sampling,the borings will be grouted to surface with neat cement. Continuous core soil samples will be collected from the borings with a 1.75-inch outside diameter (O.D.), 5-foot-long core barrel fitted with a clean, single use, polyethylene liner. The soil sampling equipment will be cleaned prior to collecting the samples as described bove. During the sampling, the core barrel will be driven in 5-foot intervals. The sample liner will be extracted from the core barrel and used for geological logging and field observations. The soil samples will be logged according to the Unified Soil Classification System (USCS). Portions of the soil samples will be placed in polyethylene bags and checked with a PID for the presence of VOCs. Geological logs will be prepared containing field observations including soil type, PID measurements, and the presence f staining or odor. Soil samples will be collected from the borings for laboratory analyses based on field observations and PID measurements. The soil cuttings will be placed in a 55-gallon drum, seated, labe ed, and left on-Site to await disposal pending results of the laboratory analyses. P:\5000 r'\5960 SIC UST RFQ\5960B County of San Joaquin-Records Center\Reports\workplan\WP 20110413.doc 31 q CONDOR