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46 to <br /> 1.0 Introduction <br />' At the request of Pacific Bell, IT Corporation (IT) has generated this work plan for additional <br /> groundwater quality assessment at the Pacific Bell facility located at 10 East 12'h Street in Tracy, <br /> California (Figure 1) This work plan has been prepared in response to a letter from the San <br />' Joaquin County Environmental Health Department (SJCEHD) requesting further delineation of <br /> petroleum hydrocarbon impact, encountered during the removal of a 2,000-gallon diesel <br /> Iunderground storage tank (UST) in March 2002 <br /> 1.1 Site Description <br /> The Pacific Bell property 1s located in a predominately residential part of Tracy, California A <br /> one-story Pacific Bell switching facility/office 1s located on the western portion of the site, with <br /> the eastern portion of the site previously occupied by parking for Pacific Bell fleet vehicles At <br /> the time of this work plan, the eastern portion of the site is presently undergoing building <br /> Iexpansion activities <br /> In March 2002, as part of the building expansion activities, a 2,000-gallon UST containing diesel <br /> fuel for an emergency backup generator was removed from the site (Figure 2) Upon completion <br /> of the expansion activities, Pacific Bell will install a new 8,000-gallon diesel UST further to the <br /> east <br /> 1.2 Site Background <br />' In February 2002, a 500-gallon heating oil UST was encountered by Pacific Bell on the <br /> southeastern portion of the site during building expansion activities The UST was subsequently <br /> removed, with no petroleum hydrocarbon analytes detected in a soil sample collected from the <br /> base of the excavation (IT, 2002a) <br />' In March 2002, the 2,000-gallon diesel UST was removed During UST excavation activities, <br /> groundwater was encountered at a depth of approximately 12 feet below surface grade (bsg) No <br /> petroleum hydrocarbon analytes were encountered in soil samples collected from the excavation <br /> floor and south end The soil sample collected from the north end of the excavation encountered <br />' 1 3 parts per million (ppm) of total petroleum hydrocarbons as diesel (TPH-D) Analysis of a <br /> groundwater sample collected from the excavation encountered 130 parts per billion (ppb) of <br /> i <br /> CNCD17-24-0210 8HARE\USTti02-0061 doc 1 <br />