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v w <br /> f ' <br /> Quarierly Summary Report <br /> Third Quarter 1998 <br /> Former Unocal Service Station 0123 <br /> 1034 Central Avenue , <br /> Tracy, California <br /> BACKGROUND <br /> The site-was repbrtedly an operating Unocal service station from 1920 through 1962. Two <br /> underground storage tank(UST) complexes have existed at.the site. A cluster of three UST's <br /> located at the northern property boundary adjacent to the I 1 t'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 propertywas 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 �ubsurface investigation was conducted by <br /> LMS. As requested by the an Joaquin County Pubhc 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 ma� 1995. Exploratory test pitting was <br /> performed and two abandoned UST's were encountered at the northern property boundary, <br /> beneath the 11'hstreet sidewalk. A report documenting the soil and groundwater <br /> investigation was submitted to Unocal and San Joa4uin County in December 1995. <br /> On September 6, 1996,Unocal submitted a corrective action plan to address hydrocarbon <br /> impacted soils that may be encountered during re . vaI 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 grout 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 /> 310-0971.B13QSR98 1 October 20, 1998 <br />