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1 - 08 June 2002 AGE-NC Project No 98-0433 ' Page 5 of 8 ' 3 3 ANALYTICAL RESULTS OF SOIL AND GRAB GROUND WATER SAMPLES TPH-g and TPH-d were detected In soil samples collected from boring B 17 at 20 feet and 30 feet ' bsg,at maximum concentrations of 71 milligrams per kilogram(mg/kg)and 230 mg/kg,respectively, In the sample from 20 feet bsg ' BTEX compounds were not detected In the soil samples analyzed MTBE was detected by EPA method 8260B in soil sample B17-20 at a concentration of 0 3 mg/kg In addition,MTBE was detested by EPA method 8021 In samples at collected at 25 feet, 30 feet and 35 feet bsg at concentrations of 0 048 mg/kg, 0 092 mg/kg and 0 03 mg/kg, respectively C" TPH-g was detected In grab ground water sample B 17 at a concentration of 240µg/l,TPH-d was not detected Ethylbenzene and total xylene were detected at concentrations of 0 61µg/1 and 1 1 Pg/l, respectively I MTBE was detected b EPA method 8260B in water sample B17 at a concentration of 160 l Y p µ� �. TBA was also detected at 36µg/1 No other target analytes were detected in the soil and grab ground water samples analyzed Analytical results are summarized In Table 3 The laboratory report (CalTech Lab ID 0202-001-1 to-6), quality assurance and quality control (QA/QC) and chain-of-custody are Included In Appendix C 3 4 GROUND WATER GRADIENT AND FLOW DIRECTION On 19 February 2002,depth to ground water at the site ranged from 19 33 to 21 09 feet below well casing tops The ground water elevations at the site ranged from 37 26 feet (MW-4) to 37 75 feet ' (MW-5) above mean sea level (MSL) The data Indicates an average decrease of the ground water elevation at the site of 0 5 feet since the previous quarterly monitoring event ' Ground water flow direction and gradient were calculated from the February 2002 gauging data An Inferred easterly trending groundwater ridge appears to bisect the site(Figure 3) North of the former UST location ground water flows northerly at a gradient of approximately 0 001 ft/ft From the former UST location southwards,groundwater flows In a south-southeasterly direction at a gradient of approximately 0 0001 ft/ft,at such a low gradient,small measurement variations can greatly affect the Inferred flow direction • The contoured ground water elevations are Illustrated in Figure 3, the depth to ground water and I calculated elevation data are presented in Table 1 Advanced Ceo>rnvironmental,Iric