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Y 27 January 2004 AGE-NC Project No. 97-0360 Page 2 of 9 2.2. UNDERGROUND STORAGE TANK REMOVAL On 12 August 1997, one 10,000-gallon diesel UST was removed from the site by Stockton Service Station, Inc. Product line(s) were also removed during excavation of the UST. During the UST removal,two soil samples were collected from the floor of the UST excavation, four soil samples from the stockpiled soil, and one grab ground water sample. Total petroleum hydrocarbons quantified as diesel (TPH-d) was reported in each of the soil samples analyzed at concentrations as high as 6,200 milligrams per kilogram (mg/kg). BTEX compounds were not detected in the soil samples analyzed. TPH-d and BTEX compounds were detected in the grab ground water sample at concentrations of 31,000 micrograms per liter (µg/I) TPH-d, 38 µg/1 benzene, 12 pg/l toluene, 53 µg/l ethylberizenc, and 68 Vg/I xylenes (Table 1). 2.3. SITE ASSESSMENT ACTIVITIES Based on analytical results of soil samples collected during the UST removal, a preliminary site investigation was required by the EHD in a letter dated 24 February 2000 (Appendix A) prior to obtaining a site closure for the former UST. The following is a brief summary of the site assessment investigations conducted at the site to date: • 25 October- and 24 November 1999 - Lush Geosciences, Inc. excavated trenches TRA through TR-9 to maximum depths of approximately 10 to 12 feet below surface grade(bsg) to assess the soil and ground water conditions at the site adjacent to J.B. Murphy Trucking. The trenches were located in close proximity to the former UST location on the property of J.B. Murphy Trucking. Soil samples were collected from depths of 8 feet and 10 feet bsg,and ground water was collected from depths of 9 and 10 feet bsg. TPH-d was detected in soil samples collected from trenches TR-1 through TR-4 at concentrations as high as 2,140 mg/kg. TPH-d was also reported in the grab ground water sample (GW-1) collected at a concentration of 508 mg/l. Only low to non-detectable concentrations of BTEX compounds were detected.Analytical results of soi I and water samples are summarized in Tables 2 and 3. Field procedures and sample results were outlined in Lush Geosciences, Incorporated Subsurface Investigation Report, dated 13 January 2000. • 13 July 2000- eight soil probe borings (P 1 through P8) were advanced at the site as part of assessment activities related to the former UST.Total petroleum hydrocarbons quantified as gasoline (TPH-g) were detected in the l0-foot soil sample collected from P4 at a concentration of 46 mg/kg. The only BTEX compound detected in soil was ethylbenzene, which was detected in the 10-foot soil sample collected from boring P4 at a concentration of 0.009 mg/kg. TPH-d was detected in soil samples collected from probe borings P 1,P4 and Advanced Geo Ln%ironmenlal,Inc.