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26 July 1999 <br /> AGE-NC Project No 97-0301 <br /> Page 8 of 9 <br /> concentrations ranging as high as 9 5 mg/kg <br /> • MTBE was not detected by laboratory analysis of soil or ground water samples <br /> • TBA was detected in ground water samples collected from P-1,P-2 and P-4 at concentrations <br /> ranging as high as 140 µg/1, DIPE was detected in a sample collected from P-2 at a <br /> concentration of 1 2 µg/l <br /> ' • TPH-g was detected in ground water samples collected from P-1, P-2 and P-4 at <br /> concentrations ranging as high as 23,000µg11, TPH-d was detected in ground water samples <br /> collected from P-1, P-2 and P-4 at concentrations ranging as high as 350,000 µg11 The <br /> ' estimated extent of dissolved TPH-g and TPH-d concentrations are depicted in plan view in <br /> Figures 5 and 6, respectively <br /> • Dissolved BTEX compounds were detected in ground water samples collected from P-1 <br /> though P-4 at concentrations ranging as high as 3,300 µg/l, the greatest benzene <br /> concentration was detected in the P-1 sample at a concentration of 1,900 µg11 <br /> • Laboratory and field data suggest that extensive petroleum hydrocarbon-impacted soil at the <br /> site exists beneath the UST area (UST removal samples TK1-E, TK2-E, TK3-E and TK3- <br /> W),north of the former UST area(P-4) at depths between 15 and 40 feet bsg and east of the <br /> former UST area(P-1) at depths between 15 and 40 feet bsg (Figure 4) <br /> • Laboratory and field data suggest the most intensely TPH-g impacted ground water is present <br /> in the area of P-1 (Figures 5) The most intensely TPH-d impacted ground water is present <br /> in the area of P-4 (Figure 6) <br /> i • The State of California drinking water standards, adopted by the Safe Drinking Water Act,have established maximum contaminant levels (MCLs) for benzene, toluene, ethylbenzene <br /> and xylenes at 1 µg11, 150 µg11, 700 4g11 and 1,750 µg11, respectively Concentrations of <br /> dissolved BTE&X compounds detected in the grab ground water samples collected from P-1, <br /> through P-4 were above selected MCLs <br /> ' • The horizontal and vertical extent of petroleum hydrocarbon-impacted soil has not been fully <br /> delineated toward the north, northeast and east <br /> • The horizontal and vertical extent of petroleum hydrocarbon-impacted ground water has not <br /> been fully delineated in any direction <br /> 6.0. RECOMMENDATIONS <br /> Based upon data collected from the site, AGE recommends <br /> Adianced GcoEn%iron mental,Inc <br /> I 1 <br />