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U U Site Background Information: Former Curtiss Pontiac-Buick AGE-NC Project No. 96-0254 Page 3 of 7 i not detected above the elevated detection Omits in the soil samples collected from the UST I excavation walls. Lead was detected at a maximum concentration of 10 mcykg. EDB was P detected in one sample at a concentration of 2.9 mg/kg. ff TPH-g and BTEX compounds were detected in the water sample at concentrations of 150,000 micrograms per liter (Ng/1) and 25,000 pg/I, 43,000 pg/I, 5,700 pg/I and 32,000 pg/I, respectively. Lead was detected at a concentration of 0.67 pg/I in the water sample; however, EDB was not detected: ` SITE ASSESSMENT INVESTIGATIONS f On 24 June 1997, a total of nine soil probe borings (131 through 139)were advanced at the site under EHD oversight. Soil in probe borings 131 through B5 were continuously sampled (cored), whereas soil in probe boring B6 was sampled at,the vadose zone/ground water interface. In addition, grab ground water samples were collected from 131 through B9. The 4 grab ground water samples and selected soil samples were analyzed for TPH-g, TPH-d, j BTEX and methyl tert-butyl ether (MTBE); however, soil samples collected from probe I{ boring B1 were notanalyzed, because field screening with'a organic vapor monitor (OVM) indicated that the samples were not impacted by petroleum hydrocarbons. • TPH-g was detected in six'sal samples collected from four of theprobe borings, B2, B3, B4 and B5. TPH-g was detected at concentrations as high as 5,000 mg/kg (135- 6') atdepths of feet bsg or less TPH-g concentrations detected in sol from depths greater than 8 feet bsg were as high as 550 mg/kg (B4-9'). TPH-g was not detected at depths of 12 to 16 feet in the area of the former USTs, nor was TPH-g detected in the soil sample collected from B6. Total petroleum hydrocarbons quantified as diesel (TPH-d) was detected in the soil sample collected from probe boring B2 at a depth of 8 feet bsg at a"concentration of 510 mg/kg. • BTEX compounds were detected in soil samples collected from depths of less than 8 feet bsg at concertrations rangingfrom 0.007 (ethyl benzene,B6-8')to 480 ng/kg (xylene, B5-6'). BTEX compounds were also detected at a depth of 12 feet bsg in borings B2, B3 and B5. No p etroleum hydrocarbons or BTE X compounds were II detected in the soil sample collected from a depth of 16 feet bsg in the former UST area. TPH-g was detected in each of the eight grab ground water samples collected from ` the site at concentrations ranging from 220 micrograms per liter (Ng/1) to 240,000 pg/I. TPH -d w as detec ted i n bot h of the grab g round w ater sa mples at concentrations of 44,000 Ng/I and 310,000 pg/I. BTEX compounds were detected in each of the water samples analyzed at concentrations ranging from 0.56 pg/I benzene in boring 131 to 20 ,000 pg/I of benzene in boring B7. MTB E was also detected at concentrations up to 1,000 pg/I by EPA Method 8020. However, the highest concentration of MTBE detected by EPA Method 8260 was 180 pg/I. Advanced GeoEnvironmental,Inc. Fi