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INVESTIGATION PROCEDURES <br /> Personnel Present: Geologist Tom Magney and Soil Scientist Jeff Gaarder directed the <br /> t <br /> field sampling, working under the supervision of California <br /> Professional Engineer Diane Lundquist. <br /> Permit: A boring permit was obtained from the San Joaquin County <br /> Environmental Health Division. A copy of the permit is included as <br /> Appendix A. <br /> Drilling Company: Gregg Drilling of Martinez, California (C57 License ## 485165) <br /> Drilling Date: October 28, 1997. <br /> 1 <br /> Drilling Methods: Geoprobe (hydraulic push with roto-hammer.) <br /> Sampling Methods: Soil lithology was logged using the Unified Soil Classification System <br /> and the Munsell Color chart. Encountered lithology is described on <br /> the exploratory boring logs presented in Appendix B. Soil borings <br /> were continuously cored and samples collected at four foot intervals <br /> for lithologic description, potential chemical analysis, and head-space <br /> analysis. Soil samples from each interval were screened for the <br /> presence of organic vapors using a photo ionization detector (PID). <br /> PID readings are recorded on the boring logs. <br /> Number of Borings: Two (SB-1 and SB-2.) <br /> Boring Depths: 31.5 and 35.5 feet below grade (fbg.) <br /> jGround Water Depths: Ground water was not encountered during this investigation. <br /> Sediment Lithology: Subsurface soil in the former UST. excavation is a clay/sand fill <br /> i <br /> mixture to a depth of 12 fbg, lying over clayey sand (SC) and sand <br /> (SP) of low to moderate permeability to 25 fbg, underlain by a sandy <br /> clay (CL) to a depth of 31.5 fbg. Sediment lithology near the <br /> northern fuel dispenser island consists of sandy clay (CL) to a depth <br /> of 9 fbg, underlain by sands (SP) and.silty sands (SM)to a depth of 3 2 <br /> fbg, underlain by a hard clay to the total depth explored. Both <br /> borings were advanced until drilling refusal was encountered. <br /> I <br /> Chemical Analyses: Two soil samples from each boring were selected for analysis. The <br /> samples were analyzed for total purgeable petroleum hydrocarbons <br /> 370 2 <br /> L <br />