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Ms. Margaret Lagorio Phase IIF )nmental Site Assessment San Joaquin County PHS-EHL Vacant Lot, 55 East Jamestown Street, Stockton, CA August 3,2000 Page 2 • ATC proposes to advance six soil borings at the site using a truck-mounted GeoprobeTM sampling system. The subsurface investigation will be conducted under the supervision of the geologist registered in the State of California. Three borings will be shallow borings advanced to approximately 10 feet below ground surface(bgs) in the suspected fuel dispenser area. Three additional soil borings will be advanced at (1) the suspected UST area, (2) the assumed upgradient side of the former gas station, and (3) the assumed downgradient side of the gas station. These three additional soil borings will be each advanced to a total depth of approximately 40 feet bgs or until groundwater is encountered, whichever is shallower. Based on the Phase I ESA, groundwater may be encountered during the advancement of these soil borings at 40 feet bgs. The soil samples cores will be collected continuously for the total depth of the borings in 4-feet long acetate sleeves from the shallow soil borings. Soil samples will be collected every 5 feet from the deeper soil borings. Using a photoionization detector (PID), ATC will screen the sample cores for levels of volatile organic compounds (VOCs). The soil sample interval having the greatest VOCs concentration from each boring, as determined using the PID, will be submitted for laboratory analysis. If no VOCs are detected using the PID, a soil sample will be selected by the field geologist for analysis from an appropriate depth. The selected depth interval for each sample will be cut from the sleeve, sealed using TeflonTM sheets and plastic end caps, labeled, placed into a chilled cooler for transport to a state-certified laboratory for analysis under chain-of-custody documentation. ATC will log the soil borings in the field by visually describing the characteristics of the soils present in the sample cores using the Unified Soil Classification System (USCS). The borings will be logged by a field geologist under the supervision of the geologist registered in the State of California. The lithologic characteristics, such as color,texture, plasticity, odor, and relative moisture content, will be noted in the field and entered onto boring logs in the field. Copies of the boring logs will be submitted with the report of the findings of the investigation. If groundwater is encountered during the advancement of the deeper soil borings, ATC will collect groundwater grab samples from the borings using disposal bailers or pre-cleaned re-usable bailers. The groundwater samples will be transferred to the appropriate laboratory supplied containers which will be closed, labeled, and placed into a chilled cooler for transport to a state-certified laboratory for analysis under chain-of-custody documentation. The soil and groundwater grab samples will be analyzed for total purgeable petroleum hydrocarbons (TPPH) and total extractable petroleum hydrocarbons (TEPH) using United States Environmental Protection Agency (USEPA) Method 8015 (modified); benzene, toluene, ethylbenzene, and xylenes (BTEX)using USEPA Method 8020; and Methyl-Tert-Butyl-Ether(MTBE) and VOCs using USEPA Method 8260. For the purpose of this workplan, ATC assumes that one soil sample will be collected from each of the soil borings for analysis. If additional soil samples are deemed necessary for analysis, ATC will collect the samples and submit them to the laboratory, but will have them put on hold pending approval by the client. ATC also assumes that one groundwater grab sample will be collected from each of the three deeper soil borings. Any soil cuttings or decontamination water generated during this investigation will be placed in DOT-approved containers that will be closed, labeled, and left onsite pending appropriate disposal. The holes made during the advancement of the soil borings will be sealed using cement grout and a tremie pipe and patched to match the surrounding ground surface. ATC ASSOCIATES INC. PROJECT NO.75.25502.0001 TASK 2 ]AIn ProgressMebberstown East\Phase IMhase 11 Workplan.doc