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30 January 2014 AGE Project No. 99-0682 Page 3 of 28 r 550-gallon waste oil UST were removed from the site by Otto Watkins, General ,/ Contractors ; the 3, 000-gale USTs were located at the southern end of the site; the 550 gallo'rrwaste oil UST was located at the northern end of the property. Approximate i{ locations of the former fuel USTs are shown on Fi� gure 2. rn+ After removal , laboratory analysis of soil samples collected from the floor of the UST excavations and dispenser areas detected total petroleum hydrocarbons as gasoline 5' ✓(7PH-g ) in soil collected beneath the 3 , 000-gallon leaded UST at a concentration of 13,400 milligrayns per kilogram (mg/kg); BTEX compounds were reported at concentrations as high j as 266 mg/kg . In addition , total petroleum hydrocarbons as diesel (TPH-d ) was reported I n the soil sample collected beneath the diesel UST at a concentration of 29 mg/kg . Background concentrations of total lead were detected in soil samples 01 P4, 31\1 and 4S . LUFT metals were detected in the soil sample collected beneath the former waste oil o ��L UST at concentrations as high as 50 mg/kg (zinc) . 2. 3 . HISTORICAL SUBSURFACE INVESTIGATIONS The following is a summary of previous site investigations of the unauthorized release of petroleum to the subsurface at the Stallworth Auto Sales site : • February 2000 - Thrge soil probbee borings (B- 1 through B-3) were advanced at the site to depths of 45 (61 ) and 35 feet bsg (B2 and B3). TPH-g was detected in soil samples from borings B- 1 through B-3 at concentrations as high as 12 , 000 mg/kg , TPH-d was detected at concentrations as high as 4, 900 mg/kg , and BTEX compounds were detected at concentrations as high as 1 ,900 mg/kg (total xylenes). One grab groundwater sample was collected from B-1 during the February 2000 investigation . TPH-g and TPH-d were detected in the grab groundwater sample at concentrations of 425, 000 micrograms per liter (pg/1) and 9, 900 pg/l , respectively. BTEX compounds were detected at concentrations of 15 , 000 pg/I , 48 , 000 pg/I , 3,200 pg/l , 55 , 000 pg/I , respectively. No fuel oxygenates were detected in the groundwater sample analysis . May2000 - Five groundwater monitoring wells (MWAA, MW-1 B and MW-2 through / • MW-4) were installed at the site. MW-1A and MW-2 are screened from 30 feet to 50 feet bsg , and MW- 113 , MW-3 and MW-4 are screened from 20 feet to 40 feet bsg . During the investigation and installations a total of 13 soil samples were submitted for laboratory analysis. TPH-g and TPH-d were detected in analyzed soil samples from boring MW-1B at concentrations as high as 6, 100 mg/kg and 2 ,600 mg/kg, respectively. BTEX compounds were detected in boring MW-11 B soil samples Advanced GeoEnvironmental, Inc.