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Quarterly Summary Report <br /> Fourth Quarter 1998 ; <br /> Former Unocal Service Station 0123 <br /> 1034 Central Avenue <br /> Tracy, California <br /> i <br /> BACKGROUND <br /> The site was reportedly an operating Unocal service Mation from 1920 through 1962. Two <br /> underground storage tank (UST) complexes have ex fisted at the site. A cluster of three UST's <br /> located at the northern property boundary adjacent t i the 11`�' Street site were,identified as <br /> "abandoned" and a second cluster of three tanks to the south were identified as active UST's. <br /> The property was purchased by Bank of America and the service station was demolished in <br /> 1962. <br /> The site is-currently an asphalt-paved parking lot owned by and servicing the Wells Fargo <br /> Bank located immediately to the south. A limited subsurface investigation was conducted by <br /> LMS. As requested by the an Joaquin County Public Health Services, Unocal submitted a <br /> work plan to perform a soil and groundwater investigation. Nine soil borings and three . <br /> groundwater monitoring wells were installed in may 1995. Exploratory test pitting was <br /> performed and two abandoned UST's were encountired at the.northern property boundary, <br /> beneath the-11 th street sidewalk. A report documentngthe soil and groundwater <br /> investigation was submitted to Unocal and San Joaq jin County in Decernber 1995. <br /> On September 6, 1996, Unocal submitted a correcti I e action plan to address hydrocarbon . <br /> impacted soils that maybe encountered during removal.of the UST's. Two abandoned 550- <br /> gallon UST's were removed in November 1996. A third UST was encountered.during the <br /> removal activities and was properly abandoned in place by grou#injection. One groundwater <br /> monitoring well was installed in December 1996 in the location of he removed UST's to <br /> evaluate soil and groundwater quality. Two groundwater monitoring wells (U-5 and U-6) <br /> were installed on October 6, 1998. In addition,one continuous core soil boring was <br /> advanced in efforts to delineate the lateral and vertical extent of hydrocarbon solvents in soil <br /> and groundwater. <br /> 9100172B14QSR98 2 January 20; 1999 <br />