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' 11 June 1999 . AGE-NC Project No 97-0333 ' Page 8 of 9 • MTBE was detected in soil samples collected from P-1, P-2, P-4 and P-5 at concentrations ' ranging as high as 110 mg/kg The estimated extent of known adsorbed MTBE is depicted in cross sectional view B -B' in Figure 6 ' • TAME and TBA were detected in soil samples collected from P-5 at concentrations ranging as high as 0 36 mg/kg ' • TPH-g was detected in ground water samples collected from P-1 through P-5 at concentrations ranging as high as 310,0004gll,TPH-d was detected in ground water samples collected from P-3, P-4 and P-5 at concentrations ranging as high as 9,100 ug/l The ' estimated extent of dissolved TPH-g concentrations is depicted in plan view in Figure 7 • BTEX were detected in ground water samples collected from P-1 though P-5 at ' concentrations ranging as high as 48,000µg/l • MTBE was detected to ground water samples collected from P-1 through P-5 at ' concentrations ranging as high as 810,000 ,ug/l The estimated extent of dissolved MTBE concentrations is depicted in plan view in Figure 8 • TAME was detected in a ground water sample collected from P-3 at a concentration of 3 6 ,ug/1 Laboratory and field data suggest extensive petroleum hydrocarbon-impacted soil at the site exists beneath the UST area (UST removal samples T1-E, T2-E and T3-E ) and north Aest of the former UST area (P-4) at depths between 15 and 25 feet bsg • Laboratory and field data suggest the greatest petroleurn hydrocarbon-impacted ground water ' is present in the area bound by P-1 through P-5 (Figures 7 and 8) The greatest dissolved petroleum hydrocarbon and MTBE concentrations are located near probe borings P-1 and ' P-5 • The State of California drinking water standards adopted by the Safe Drinking Nater Act have established maximum contaminant levels (MCLS) for benzene, toluene, ethylbenzene ' and xylenes at 1 pg/l 150 �tg/l, 700 ug/l and 1,750 pg/l, respectively Concentrations of dissolved BTE&X compounds detected in the grab ground eater samples collected from P-1 ' P-4 and P-5 were aboN e MCLS • The DHS adopted a concentration of 13 ugll as an action level for M FBE in March 1999 and a concentration of 5 ,ug/1 as a secondary MCL in January 1999 At this point in time, the, MTBE concentrations detected at P-1, P-4 and P-5 exceed the action Ie�el, P-1 through P-5 exceed the secondary MCL as determined by EPA Method 826011\4 anak sis ' b 1-he horizontal and vertical cvtent of petroleum h}drocarbon-impacted soil has nal been fully delineated toward the north south, east and nest 4rhanrtd6eo!-nN;ronmenfe, i❑