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1.0 Introduc i <br /> t on <br /> IT Corporation (TT) 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, Califomia, 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 December 1992 <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 borings <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 MW- <br />' 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 (Table 3) <br /> 3.0 Quarterly Activities <br />' The wells were sampled and groundwater elevations recorded on December 21, 1992 (fourth <br />' quarterly event) Water-level data was collected so gradient and flow direction could be <br /> calculated. Sampling procedures conformed to California Regional Water Quality Control <br /> Board and San Joaquin County Environmental Health guidelines At least three well volumes <br />' of water were purged pnor to the collection of samples Measurements of pH, temperature, <br /> MZ/01-19-93/ENG/'93-0005 MER 1 <br />