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• 18 November 2004 <br /> AGE-NC Project No 97-0301 <br /> Page 3 of 6 <br /> I <br /> Benzene,toluene, ethylbenzene, and xylenes (BTEX),methyl tertiary-butyl ether(MTBE), <br /> i1,2-Dichloroethane(1,2-DCA),ethylene dibromide(EBD),di-isopropyl ether(DIPE),ethyl <br /> ter -butyl ether(ETBE),tert-amyl methyl ether(TAME),and tertiary butanol(TBA)by EPA <br /> Method 8260B <br /> I <br /> 3.0. FINDINGS <br /> Grolvd water elevation, flow direction, and gradient were determined from field data collected <br /> ' on June 2004 The contaminant impact to ground water was quantified by the ground water <br /> samples collected on 18 June 2004 <br /> 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> The depth to ground water measurements at wells MW-1 through MW-12 varied between 33 08 feet <br /> (MW-9B)and 34 88 feet(MW-8C)below the tops of the well casings,'round water elevations were <br /> calculated to be between 20 88 feet (MW-8A) and 22 10 feet (MW-11D) below mean sea level <br /> (MSL) Generally, ground water elevation at the site decreased an average 3 44 feet between the <br /> March 2004 and the June 2004 ground water monitoring events ,- <br /> ' 1 b of <br /> Ground water elevation data collected on 17 June 2004 from wells MW-8 (A-C),MW-9(A-D),and <br /> MW-12 (A-D)is depicted on cross section D-D'(Figure 3) By determining the difference between <br /> ' ground water elevations(dh)and dividing by the difference of the screen interval midpoints(dl),the <br /> vertical gradient between adjacent screen intervals was calculated Generally, moderately steep to <br /> steep downward vertical gradients were observed between the Second, Third, and Fourth Water <br /> 1 Zones,while a very slight upward vertical gradient was observed between the First Water Zone and <br /> the Second Water Zone (Figure 3) -- <br /> ' The ground water elevations at wells MW-1 through MW-12 were calculated by subtracting the <br /> measured depth to ground water from the surveyed casing elevation The June 2004 ground water <br /> elevation data collected from wells MW-1 through MW-7 were plotted for the First Water Zone <br /> (Figure 4) as defined in AGE's CPT Site Investigation - Third Quarter 2001 (dated 25 October <br /> 2001) Generally, the net ground water flow direction was toward the east to northeast at an <br /> ' approximate hydraulic gradient of 0 003 foot/foot (ft/ft) <br /> I ' Advanced GeoEnviron mental,Inc <br />