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' 08 September 1999 <br /> • <br /> AGE-NC Protect No 95-0103 <br />' Page 8 of 9 <br />' • The greatest concentrations of petroleum hydrocarbons as gasoline were detected in samples <br /> collected from well MW-3 west of the site Hydrocarbons were detected at lesser <br /> concentrations in wells MW-1, MW-4 and MW-5 and vapor well VE-1 <br /> • The highest concentration of benzene was detected in the sample collected from monitoring <br /> well MW-4 at 740 ,ugll Benzene was also detected in four of the conformation grab water <br /> samples collected from the site at a maximum concentration of 150 4g/l (CHP5) Benzene <br /> was detected in samples collected from grab water sample CHP6 and CB3 at concentrations <br /> of 1 2 ,ug/l and 2 8 ,ug/l The lack of detection of benzene In sample CHP1, CHP2, CHP3, <br />' CHP7, CHP8 and CHP 9 limit the petroleum release to the areas under the building, the <br /> north and western ends of the site and an area extending 140 feet west of th_- site <br />' • The current distribution of detectable benzene in ground water samples collected is presented <br /> in Figure 6 <br /> • A reduction of the dissolved-phase hydrocarbon plume concentrations on the site has <br /> occurred The current concentrations of benzene in samples MW-1 and MW-4 are less than <br /> 0 02 % and 1 6 %, respectively, of the highest concentrations of benzene detected in samples <br />' • collected from the monitoring wells <br /> • MTBE was detected in the ground water sample from well MW-1 at a concentiatlon of 2 3 <br /> µg11, and was detected in the sample from MW-4 at a concentration of 7 5 Mcg/l by EPA <br />' Method 8020, but the latter sample ,��as not analyzed by EPA Method 8260 <br /> 5.0 RECOMMENDATIONS <br />' Based on data collected over the quarter at the site, AGE recommends <br /> • Continued monthly and quarterly ground water monitoring The next ground water <br />' monitoring event is scheduled for September During the next quarterly sampling event, <br /> collect mater samples from selected wells to allow for the most representative ground water <br /> data (I e all vapor wells with screens In the current water table level) <br /> 1 <br />' 6.0 LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br />' environmental consultants practicing in this or similar localities The findings were based upon <br /> analytical results provided by an independent laboratory Evaluation of the geologic/hydrogeologic <br />' Adianced GeAnsironmental,Inc <br />