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7 I <br /> 02 September 2003'. <br /> AGE-NC Project No. 98-0468 <br /> Page 3 of l l <br /> 2.4. HISTORICAL PETROLEUM.RELEASE AND ASSESSMENT <br /> 2.4.1' Gasoline/Diesel UST Removal <br /> In April 1991, a 550-gallon gasoline UST was removed from the site:During removal of the UST; <br /> g g g <br /> a single soil sample was collected in the vicinity of the former fuel dispenser at .four feet below <br /> ' surface grade (bsg).'Laboratory analysis of the soil'sample detected total petroleum hydrocarbons <br /> as gasoline (TPH-g) and total petroleum hydrocarbons as diesel (TPH-d). In January 1994, a 1,000 <br /> gallon diesel UST was removed from the site. During UST removal activities, a single soil sample <br /> ' was collected beneath the west end of the former UST at a depth of 11 feet bsg. Laboratory analysis <br /> of the soil sample detected TPH-g, TPH-d, benzene, toluene, ethylbenzene, and total xylenes <br /> (13TEX). <br /> 2.4.2., Preliminary Soil and Ground Water Assessment <br /> In June 1994, soil and ground water assessment activities were conducted at the site. A total of three <br /> soil borings were completed, soil samples were collected for analysis, and three monitoring wells ' <br /> ' (MW-1 through MW-3) were installed in the location of the soil borings (Figure 2). Relatively low <br /> concentrations of TPH-d were detected in two of the six soil samples collected from the soil borings. . <br /> During the period frorri June 1994 through September 1995, three ground water sampling events <br /> were conducted at the site.During the June 1994 sampling event,laboratory analysis of ground water <br /> ' samples collected from monitoring well MW-3 detected relatively low concentrations of benzene <br /> (1.4 micrograms per liter: µg/1), total xylenes (1.7 µg/l),.and TPH-g(55 µg/1). There were no other <br /> reported detections of petroleum hydrocarbon compounds in any of the monitoring wells during the <br /> June 1994, October 1994, or September 1995 sampling events. <br /> ' 2.4.3. 'Soil Excavation and Sampling <br /> In April 1995,petroleum hydrocarbon-impacted soil was excavated and removed from the area of <br /> ' the former diesel UST. During the excavation activities, soil samples were not collected.due to <br /> encountering the ground water table above the base of the former tank excavation. Therefore, a <br /> ground water sample was collected from the excavation. Laboratory analysis of the ground water <br /> ' sample detected elevated levels of benzene (1,000 µg/1), toluene (2,000 µg/1), ethylben2ene (800 <br /> µg/l), total xylenes (6,400 µg11),,and TPH-g (17,000 gg/1). <br /> In August 1995, additional petroleum hydrocarbon impacted soil was excavated and removed from <br /> • the former diesel UST..location and soil samples were collected for analysis. Laboratory analysis of <br /> ' Advanced GeoEnvironmental,Inc. ' <br />