ARCHIVED REPORTS XR0004698 - Laserfiche WebLink

Home Browse Search

. 20 March 2002 ' AGE-NC Project No 95-0144 Page 5 of 7 I 4 1 RELATIVE 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) Between November 2001 and February 2002, ground water elevation increased between 0 66 feet and 1 05 feet in the monitored wells The approximate hydraulic gradient for the February 2002 monitonng event was inferred to be 0 003 ft/ft with a flow direction toward the north-northeast Ground water elevation contours derived from data collected on 13 February 2002 are depicted in Figure 3 Ground water was between approximately 0 17 feet and 5 19 feet above the screened interval in monitoring wells MW-1,MW-2,MW-4,MW-5,MW-8, ' MW-11 and MW-12 Ground water was within the screened intervals of MW-13, MW-19A, MW-20A and MW-21A Ground water elevations in nested wells MW-19,MW-20 and MW-21 were between 1 41 feet and 168 feet lower in deeper screened intervals beneath a clay layer than in the shallower screened intervals Data from wells with the upper screened intervals,established in first-encountered ground ' water,was utilized for gradient determination ' . 4 2 ANALYTICAL RESULTS OF WATER SAMPLES i During the February 2002 monitoring event,TPH-g was detected in samples from monitoring wells MW-21A and MW-21B at concentrations of 4,500 micrograms per liter (µg/1) and 700 gg/l, respectively Various BTEX compounds were detected in samples from wells MW-21A and MW-21B at concentrations as high as 200 gg/1 (ethylbenzene, MW-21A) TPH-d was detected in samples collected from MW-20A,MW-2l A and MW-21B at concentrations of 190µg/1,7,700µg11 and 620 µg/1, respectively TPH-mo was detected in monitoring well sample MW-21A at a ' concentration of 930 µg/1 The extent of hypdrocarbon-impacted ground water is illustrated in Figure 4 MTBE was detected in ground water samples from MW-2, MW-4, MW-13, MW-19A, MW-19B and MW-21B at concentrations ranging from 12 µg/1 in MW-21B to 2 9 µg/1 in MW-MW-4 Historically, only low concentrations of MTBE and TBA have been detected intermittently at the ' site Analytical results for the first quarter 2002 monitoring event are summarized on Tables 2 and 3 Analytical results of recent and historical ground water samples are summanzed on Tables 4 and 5 The laboratory report(MAI Lab IDs 90455 through 90464)and chain-of-custody forms are included in Appendix B Advanced GeoEnvjronmental,Inc 1