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1.0 Introduction <br /> IT Corporation (IT) was retained by Pacific Bell to execute the verification monitoring <br /> program proposed in the IT Corporation, Site Investigation Report, Pacific Bell, Facility No <br /> UE042, 345 North San Joaquin Street, Stockton, California, March 1992 <br /> The verification monitoring program consists of the sampling and analysis of groundwater <br /> samples collected from three off-site monitoring wells This report summarizes the quarterly <br /> monitoring event conducted during May 1994 <br /> 2.0 Site Background <br /> The Pacific Bell facility located at 345 North San Joaquin Street in Stockton consists of a <br /> building which covers the entire site - half a block (Figures 1 & 2). In December 1990, two <br /> diesel UST's (300 gallon and 550 gallon) located beneath the basement floor in the center of <br /> the facility building were closed in place by filling with a cement slurry. Several bonngs <br /> were hand bored beneath the tanks and total petroleum hydrocarbons expressed as diesel were <br /> found in the soil as high as 22,000 ppm <br /> In December 1991, IT Corporation installed three monitoring wells in the streets around the <br /> site (Appendix A) In the soil samples analyzed, no total petroleum hydrocarbons as diesel, <br /> was observed, however, in the upgradient boring, TPH as gasoline was observed (7 4 ppm) <br /> Benzene, toluene, ethyl benzene, and xylenes (BTEX) were identified in soil samples in <br /> MW-2 (downgradient) and MW-1 (upgradient) <br /> BTEX constituents were not observed in any of the groundwater samples collected during the <br /> initial sampling, however, the groundwater samples from MW-1 and MW-2 contained 130 <br /> ppb and 52 ppb TPH as diesel, respectively Analysis of groundwater samples, collected <br />' during four consecutive quarterly sampling events, revealed no detectable petroleum <br /> hydrocarbons <br />' In February 1993, IT Corporation installed six off-site soil borings to examine the extent of <br /> petroleum hydrocarbon migration from the site Analysis of soil samples from these <br /> boreholes revealed no detectable petroleum hydrocarbons. Analysis of groundwater samples, <br /> collected from the boreholes, revealed no detectable diesel concentrations No detectable <br /> MZ/05-17-94/UST/94-0075 NBR 1 <br />