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Ir T{ ibl i . Subsurface Conditions Twelve exploratory soil borings were advanced on-site at the locations shown on Figure 1 PB- 1 through PB-9 were drilled for site assessment, Borings TP-N, TP-E and TP-S were drilled for soil chemical analysis for possible vadose zone contamination in the former tanks pit area The site is underlain by clayey soils, which locally contain thin fine grained sand laminae to depths of about 7-feet Sand and clayey sand underlie the clay to depths of about 1 1-feet This strata may internally contain coarser sand in the vicinity of PB-7, although the strata appears to become more interbedded clay and sand overall to the north (onto Tracy High Property) A salty clay underlies the sandy strata and was encountered in each borehole between 1 1- to 12- feet (see Figure 2) These data indicate a relatively continuous but possibly leaky aqutard under the site Groundwater was encountered in each borehole at depths of about 7-feet, and water appeared to be unconfined and entered some boreholes slowly Upon completion all borings were sealed with cement grout Chemical and Physical Analysis and Results Six soil and eight groundwater samples were analyzed in the field to a Monroe Laboratories, Inc mobile laboratory, and eight soil and one groundwater samples were analyzed at Priority Environmental Laboratories, Inc in Milpitas, CA, both State certified analytical laboratories Selected samples were tested for the following, Total Petroleum Hydrocarbons as Gasoline (TPHG), Benzene (B), Toluene (T), Ethylbenzene (E), Xylene (X), using EPA Methods 5030, 8015, and 8020 Two soil samples were analyzed by Priority for Total Organic Carbon (TOC), and one soil sample was analyzed for particle size gradation at PB-8-3, in the aquifer strata The results are attached (see Appendix D) and listed below in Tables 1 and 2 TABLE 1. SOIL CHEMICAL DATA Sample TPHG Benzene Toluene Ethylbenzene Xylene TOC No mg/kg ---------------------------ug/kg------------------------- mg/kg PB-1-2 ND ND ND ND ND NA PB-2-2 ND ND ND ND ND NA PB-3-2 ND ND ND ND ND NA PB-4-2 ND ND ND ND ND NA PB-5-2 ND ND ND ND ND NA PB-6-2 ND ND ND ND ND NA PB-7-2* 37 ND 56 so 25 4190 PB-8-2* 37 10 30 87 230 4980 TP-E-6'* ND ND ND ND ND NA TP-E-8'* ND ND ND ND ND NA TP-N-4'* ND ND ND ND ND NA TP-N-8'* ND ND ND ND ND NA TP-S-4'* ND ND ND ND ND NA TP-S-8'* ND ND ND ND ND NA 0 Mr Ed's Muffler Project No 4090-P Page 4