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�f f: <br /> BASELINE ASSESSMENT REPORT <br /> Site Number 11195 <br /> 16500 South Interstate 5 <br /> Lathrop, California <br /> 4. Supplemental Site Assessment Work <br /> EMCON conducted additional site assessment activities at the site on November 18, 1994. <br /> Two exploratory borings (THP-1 and THP-2) were advanced 16 feet bgs by using CPT <br /> equipment (Figure A-1). THP-1 was located between the station building and the UST <br /> codex, and THP-2 was located just off the southwest corner of the station building near the <br /> waste oil UST. Soil types encountered during drying generally consisted of silty sand to <br /> approximately 13 feet bgs, underlain by sand or silly sand to the total depth explored. <br /> r .� Groundwater was encountered at approximately 12 feet bgs. PID readings up to 8.1 ppm were <br /> r= ' measured from soil samples collected from both THP-I and THP-2. <br /> Soil samples collected from THP-1 at 5 and 6 feet bgs and from THP-2 at 7.5 and 10 feet bgs <br /> were submitted for analyses of THP-G, TPH-D, TPH-O, and BTEX. The deeper samples <br /> from each boring were also analyzed for HVOCs. Laboratory results indicated concentrations <br /> of TPH-D(1 ppm) and TPH-O (5 ppm)in the sample from THP-2 at 7.5 feet bgs (Table A-1). <br /> Neither BTEX nor TPH-G was detected in any of these samples. <br /> Groundwater samples from both borings were collected by using HydroPunch equipment. <br /> These samples were submitted for analyses of TPH G, TPH-D, TPH-O, BTEX, and HVOCs. <br /> EMCON observed a slight petroleum hydrocarbon-like odor in the groundwater sample from <br /> THP-1. The sample from THP-1 contained TPH-G (99 ppb), TPH-D (370 ppb), and TPH-O <br /> (3,000 ppb); BTEX was not detected in this sample (Table A-1). Only benzene (1.7 ppb) was <br /> detected in the sample from THP-2. <br /> EMCON personnel also checked beneath the pump island dispensers for the presence of spill <br /> containment boxes and for indications of possible leakage. Gravel was accessible beneath each <br /> dispenser except the south dispenser of the west pump island; the gravel beneath this dispenser <br /> was visibly stained. PID readings of the headspace in TD-1, TD-3, and TD-4 were as high as <br /> 18 ppm. A sample collected from beneath TD-1 was submitted for TPH-G, TPH-D, TPH-O, <br /> BfMS/RPT/I l I95RPT.d t6-94/LAWb:5 Rev.0,02!03/95 <br /> 0952-093.03 <br /> 1 <br />