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I j enviros® i hydrocarbons from soil Soil samples collected from the new borings corresponded to depths where previous soil samples indicated the presence of petroleum hydrocarbons Soil samples were collected at five-foot intervals for chemical analysis and lithologic description An Enviros geologist supervised the drilling and described encountered soils using the Unified Soil Classification System and Munsell Color chart Encountered lithology is described on the exploratory boring logs presented in Appendix A and a summary of the boring data is presented in Table 1 Soil sample tubes selected for laboratory analysis were covered with Teflon tape, capped, labeled, entered onto a chain-of-custody record, and stored in a cooler with ice The samples were transported to Sequoia Analytical (Sequoia) in Redwood City, California, a state-certified environmental laboratory Soil samples from the eight borings were analyzed for Total Purgeable Petroleum Hydrocarbons (TPPH) according to EPA Method 8015 (Modified), benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl-tertiary-butyl-ether(MTBE) according to EPA Method 8020 Additional analyses were performed on the soil sample collected from Boring B-4 from a depth of 25 5 feet below grade (fbg), which included Fractional Organic Carbon Content (FOC), Porosity, Permeability, and Toxicity Characteristic Leaching Potential (TCLP) for TPPH and BTEX (TCLP-TPPH & BTEX) The soil sample from 20 fbg from Boring B-5 was analyzed for TCLP-TPPH & BTEX and FOC The soil sample • from 20 fbg from Boring B-7 was analyzed for TCLP-TPPH & BTEX Decontamination Procedures Drilling and sampling equipment were decontaminated prior to beginning work and between setting up the dnll rig at each boring location Drilling equipment was inspected prior to drilling each boring 2.2 Soil Stockpile Approximately 3 cubic yards of soil were generated as a result of drilling activities This soil was temporarily stockpiled on and covered with visqueen The stockpile was sampled for chemical analysis of TPPH, BTEX, and Total Threshold Limit Concentration (TTLC) lead The soil stockpile was accepted for disposal at the Forward, Inc facility in Manteca, California, and was transported on April 29, 1996 3.4 FINDINGS 3.1 Geology and HydrogeoIogy Lithology encountered during the drilling of the exploratory soil borings consisted of clay (CL), silt (ML), clayey sand (SC), silty sand (SM), and sand (SP) to a maximum depth explored of approximately 415 fbg Ground water was encountered in Borings B-3 through B-6 The depth to first encountered ground water in these borings ranged from • 24 5 to 29 5 fbg 369 2 L