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' 15 February 2006 <br /> AGE-NC Project No 95-0184 <br /> Page 6 of 7 <br /> samples, and remained stable or decreased slightly in the monitoring wells as compared to <br />' the previous quarter All BTEX compounds were found in all ground water samples <br /> collected Concentrations of BTEX compounds were detected above the solubility limits for <br /> water, therefore free-phase product may be present in coarse grained soils at the site or <br />' adsorbed hydrocarbons are being readily liberated during the ground water purging <br /> procedures <br />' MTBE was detected in s�es from wells MW-4, VW-2B, VW-3 and VW-4 at <br /> m <br /> concentrations ranging frog/1 (VW-3)to 320 µg/l(VW-4) 1,2-DCA was detected in <br /> MW-1, MW-2, MW-4, MW-7, VW-2B, VW-3, VW-4, VW-513, and VW-5C at <br /> concentrations ranging from 2 5 µg/l (MW-7) to 280 µg/l (VW-4), EDB was detected in <br /> MW-4 and VW-2B The concentrations of MTBE, 1,2-DCA, and EDB in the ground water <br /> samples exceed their respective MCLs for drinking water <br />' A map of dissolved TPH-g, benzene, MTBE and 1,2-DCA concentrations are shown on <br /> Figures 4 through 7 <br />' Naphthalene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and n-propylbenzene were <br /> detected in ground water samples at concentrations above the DHS-recommended drinking <br /> . water Action Levels VOC concentrations have decreased in wells VW-4 and VW-5B and r <br /> remained relatively stable in the remaining wells <br /> • The vertical and lateral extent of impacted soil and ground water has not yet been defined <br /> The concentration of dissolved constituents collected in samples from deeper monitoring _ <br /> wells have been documented to be lower than the shallow, vapor well samples Therefore, '" <br /> the maximum concentration of the release appears to reside in the upper 50 feet of the �' <br /> subsurface f <br /> 5.0. RECOMMENDATIONS <br /> Based upon data collected from the site <br /> AGE recommends continued quarterly ground water monitoring of selective with the <br />' removal of the full scan for VOCs <br /> AGE recommends implementation of interim ground water remediation and soil vapor <br />' extraction Ground water extraction utilizing the current monitoring well network would <br /> exert hydraulic control on the water table and extraction of the most severely impacted <br /> r- <br /> ground water An expected ground water flow rate of only two to three gallons per minute ��� <br />' per well should be satisfactory to accomplish a significant mass reduction at the most <br /> severely impacted monitoring/vapor wells <br /> , J rc � <br />' Advanced GeoEnv►ronmental,Inc 7'r j 6t <br />