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' � d <br /> KEI-J92-0205 .R4 <br /> July 6, 1994 <br /> Page 2 <br /> The former Unocal site is surrounded by several large-scale <br /> petroleum storage and distribution facilities. It is KEI's <br /> understanding that several documented unauthorized releases have <br /> occurred at these sites. It is further KEI ' s understanding that <br /> the responsible parties for these sites have combined to perform an <br /> extensive regional soil and ground water contaminant investigation <br /> (piezometers P14 and P15, located at the rear of the former Unocal- <br /> leased site, were apparently part of this Investi.gation) . The <br /> extent of the contaminant plume caused by the operation of the <br /> ad3acent oris currently <br /> unknown Eappears athn <br /> eastern portion theformerUncalleased propertyhas <br /> beee <br /> impacted by this plume. <br /> The sub3ect site is owned by the Port of Stockton, and has been <br /> leased by Southern Pacific Pipelines, Inc Unocal entered into a <br /> sublease agreement with Southern Pacific in 1974-1975, and began <br /> operation of the former facility in 1975. In approximately 1979 , <br /> Unocal subleased the northeast Poses°(F�guthe <br /> he1). Thesite to <br /> Unocal <br /> Standard Transmission (ST) <br /> facility was operated between 1975 and 1992 , when the master lease <br /> beteen the refore <br /> Port <br /> Pacific bet e n Unocal and Southern Pacific) wasnterminated. <br /> the sub <br /> During the construction of the Unocal facility in the mid-1970 's, <br /> two underground storage tanks were installed at the site (10 , 000 <br /> gallon and 20, 000 gallon capacity, respectively) . Based on <br /> background information gathered by Unocal, these tanks were <br /> predominantly used to store diesel for use as fuel by the distribu- <br /> tion fleet at the site. According to records researched by Unocal, <br /> the refined products (i. e. , super unleaded gasoline, unleaded <br /> gasoline, and diesel fuel #2) that were distributed to commercial <br /> accounts were withdrawn for distribution from their loading facilities <br /> were stored at the nearby ST Services loading rack <br /> andndwere <br /> In 1988 Kleinfelder installed seven monitoring wells and two <br /> exploratory borings during a soil and ground water assessment at <br /> the Unocal site. Documentation of the sample collection techniques <br /> and analytical results are presented in Kleinfelder' s "Problem <br /> Assessment Report" (Kleinfelder Job No. 24-2059-01) dated September <br /> 1, 1988 . The locations of the monitoring wells and borings <br /> installed by Kleinfelder are shown on the attached Figure 1. The <br /> les <br /> installation are summarized in theesults of the soil sattached Tablesd during 4 and 5. well <br /> installati <br /> KEI ' s field work at the subaect site began on April 22 , 1992 , when <br /> two underground diesel storage tanks (with capacities of 10, 000 and <br /> 20, 000 gallons, respectively) were removed from the site. The <br /> • tanks were made of <br /> Ms. P mela apparent <br /> of tt holes <br /> scracks or <br /> the San Joaquin <br /> observed in <br />