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UNDERGROUND STORAGE TANK REMOVAL • ' An unnamed service station operated at the site from the 1940's until the 1960's Reportedly four USTs were filled with sand and abandoned an place in the late 1960's A Standard Oil Service Station operated at the site from the 1960s until 1980 Subsequently, the USTs associated with this fuel system were removed, the location of the former USTs during this period is uncertain, but is believed to be at the northeast corner of the site Neither UST decommissioning was verified with soil sample collection PREVIOUS SITE ASSESSMENTS S SSMENTS Ten soil bonngs have been advanced and three ground water monitoring wells have been installed at the site to assess the vertical and lateral extent of impacted soil and ground water The following is a summary of milestone events at the site On 22 May 2000, a total of seven on-site soil borings were established by Hydro-Geo Consultants I Inc with a Geoprobe sampling ng Borings A, B and C were established on the northeast corner of the site and borings D through G were established on the west and southern edge of the former service station location,to a depth of 45 feet below surface grade(bsg) Based on laboratory analysis lieTotal petroleum hydrocarbons as gasoline and diesel (TPH-g and TPH-d) were detected in soil samples collected during boring operations at concentrations as high as 300 milligrams per kilogram(mg/kg) and 2,400 mg/kg, respectively, in the sample from boring A at 30 feet bsg BTEX compounds were detected in the soil samples at maximum concentrations of 0 5 mg/kg(toluene), 1 5 mg/kg(ethylbenzene)and 30 mg/kg(xylenes)in the sample from boring A at 40 feet bsg • TPH-g and TPH-d were detected in grab ground water samples collected during the soil boring operations at concentrations as high as 470,000 micrograms per liter (4g/1) and 230,000 µg/l,respectively,in the sample from boring A Dissolved BTEX compounds were detected at maximum concentrations of 1,900 µg/1 benzene, 4,100 µg/1 toluene and 3,600 µg/1 mg/kg ethylbenzene in sample A and 35,000 µg/1 xylenes in sample B On 31 January 2002, three additional soil probe borings were advanced,two bonngs were advanced I on-site to a depth of 90 feet bsg (I and J), while boring H was established off-sate across California Street to a depth of 50 feet bsg Laboratory analysis indicated I TPH-g and TPH-d were detected an grab ground water samples collected during the soil boring operations at concentrations as high as 120,000µg/1 and 190 µg/l,respectively,in the sample from boring J at a depth of between.46 and 50 feet bsg Dissolved BTEX compounds ' were detected at maximum concentrations of 650 µg/1 benzene in sample I at a depth of • between 46 and 50 feet bsg and 9,000 gg/1 toluene,2,900µg/1 mg/kg ethylbenzene and 9,000 µg/1 xylenes an sample J at a depth of between 46 and 50 feet bsg I