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i I ' 02 March 2004 i AGE-NC Project No 95-0144 Page 3 of 5 t3 0• FINDINGS Ground water elevation and flow direction were inferred from field data, hydrocarbon-impact to ' ground water was quantified from laboratory analysis of the ground wafer samples AGE believes that through an oversight, nested monitoring well MW-21AB were inadvertently sampled and labeled as MW-19AB, therefore the findings will document the analytical results of well MW-21 3 1 GROUND WATER ELEVATION AND GRADIENT The elevation of ground water In each well was calculated by subtracting the depth to water from the surveyed casing elevation(Table 1) During the October 2003 monitoring event the average ground water elevation at the site was 9 0 feet below mean seal level(MSL), a decrease of 12 feet since the August 2003 monitoring event The average depth to water at the site was approximately 18 9 feet bsg The approximate hydraulic gradient for the October 2003 monitoring event was inferred to be ' 0 003 ft/ft with a flow direction toward the north-northeast In the Upper Water Zone (Figure 3) ' Ground water was within the screened intervals of shallow-screened wells MW-11, MW-12, MW-13,MW-18,MW-19A,MW-20A and MW-21 A,but was between 0 17 feet and 3 09 feet above the screened interval in the shallow-screened wells MW-1, MW-2, MW-4, MW-5 and MW-8 ' Ground water elevations in the deep-screened nested wells MW-1913, MW-20B, MW-21B and MW-25, screened in the Lower Water Zone, were between 0 55 feet and 173 feet lower than in the wells screened in the Upper Water Zone The approximate hydraulic gradient in the deeper-screened ground water monitoring wells for the October 2003 monitoring event was inferred to be 0 002 ft/ft with a radial flow pattern generally toward the west-southwest (Figure 3 - see blue lines) 1 , 32 ANALYTICAL RESULTS OF WATER SAMPLES During the October 2003 monitoring event, TPH-g was detected' in ground water samples collected from monitoring wells MW-21A, MW-21B and MW-20A at concentrations of 3,300 micrograms ' per liter (gg/I), 620 gg/l and 52 �Lg/l, respectively TPH-d was detected in samples collected from wells MW-21A, MW-21B and MW-20A at concentrations of 5,700 µg/l, 620 µg11 and 82 Pg/l, respectively Benzene was detected in samples collected from wells MW-21A and MW-20A at ' concentrations of 170 gg/1 and 0 65 µg/l, respectively Ethylbenzene and xylenes were detected in wells MW-21A and MW-21B at concentrations as high as 120 pg/l (MW-21A) and 13 µ0 ' (MW-21 A), respectively Other target analytes were not detected above laboratory reporting limits In the samples collected from the monitoring well network Advanced GeoEnvi ron mental,Inc a