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' 08 December 1998 • AGE-NC Protect No 95-0144 ' Page 5 of 7 Oxygenated compounds were not detected in the soil samples analyzed from the site Seven volatile ! organic compounds were detected in samples collected from MW-21 by EPA Method 8260 Volatile organic compounds were not detected in the samples analyzed from borings MW-19 or MW-20 Analytical results of soil samples are summarized on Tables 1 and 2 The laboratory report (MAI Sample Nos 91032-91042) and chain-of-custody forms are included in Appendix B 3 3 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 3) Ground water elevation decreased an average of 0 40 feet between May and August 1998 The approximate hydraulic gradient for the current monitoring ' period was calculated to be 0 003 ft/ft with a northerly flow direction Ground water elevation contours derived from data collected on 12 August 1998 are depicted in Figure 3 Ground water was ' between four and six feet above the screened interval in monitoring wells MW-1, MW-2, MW-4, MW-5 and MW-8 Ground water was approximately one to three feet above the screened interval in MW-11, MW-12, MW-13 and MW-18 Ground water elevations in wells MW-19, MW-20 and MW-21 were approximately two feet lower in the lower screened intervals beneath the confining clay layer than in the upper screened interval ' Data from the upper screened interval, established in first-encountered ground water was used for 7 gradient determination 34 ANALYTICAL RESULTS OF WATER SAMPLES ' During the August 1998 monitoring, TPH-g was detected in monitoring wells MW-21A and MW- 21 B at concentrations of 9,000 parts per billion (ppb, reported as micrograms per liter) and 2,600 ppb, respectively BTEX were detected in MW-21A and MW-2113 at concentrations as high as 230 ' ppb (ethylbenzene, MW-21A) Toluene was detected in MW-20B at a concentration of 0 56 ppb TPH-d was detected in wells MW-13, MW-19A, MW-1913, MW-20A, MW-2013, MW-21A and ' MW-21 B at concentrations ranging from 69 ppb to 7,800 ppb TPH-mo was detected in samples collected from MW-19A, MW-1913, MW-20B and MW-21A at concentrations as high as 790 ppb Other petroleum hydrocarbons were not detected at the site during the August- 1998 monitoring event MTBE was detected in MW-19A,MW-I 9B and MW-2 I B at concentrations as high as 1 3 ppb TBA was detected in MW-20A, MW-20B and MW-21A at concentrations as high as 16 ppb' Other oxygenated compounds were not detected at the site Thirteen volatile organic compounds were g P detected at the site at concentrations as high as 250 ppb (1,2,4-trimethylbenzene, MW-2113) ' Advanced GcAn%ironmcntal,Inc 3 a t