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(EDB) remained in soil in the presumed source area. It is assumed that the remediation <br /> system has reduced these soil impacts since this data was collected. <br /> 2.4 DISTRIBUTION OF HYDROCARBONS IN GROUNDWATER <br /> MTBE has been detected at this site, but at low concentrations. During the first quarter <br /> 2009, MTBE was only detected in well VEW-7 at 36 micrograms per liter (µg/L). TPHg <br /> and BTEX are the constituents of concern (COC) at this site. TPHg, benzene, and <br /> depth-to-water versus time graphs for select wells are provided in Appendix D. On-site <br /> wells MW-1 through MW-3, MW-5, MW-13, MW-14, and VEW-5 are currently below or <br /> near detection limits. <br /> The source area has been identified as the former UST area. Wells VEW-2 through <br /> VEW-4 monitor this area. VEW-2 TPHg and benzene concentrations remain elevated <br /> despite DPE, but show a slow declining trend. Declining TPHg and benzene <br /> concentration trends are evident in wells VEW-3 and VEW4. TPHg and benzene in <br /> VEW-3 are approaching acceptable levels,iwhereas the concentrations for these <br /> constituents in VEW4 remain moderately elevated. It should be noted that well VEW-4 <br /> is screened deeper that the other VEW wells. Also, concentrations in these wells have <br /> varied with groundwater level changes. <br /> Well VEW-7 is located on the fringe of the source area,near the current USTs. Although <br /> groundwater level variations affect hydrocarbon concentrations in this well, the overall <br /> trend is decreasing. Moderate concentrations of TPHg and benzene remain in well <br /> VEW-7. Well MW-4 is located at the southeast corner of the site. The TPHg and <br /> benzene concentration trend in this well reversed in 2004 and began increasing. Current <br /> concentrations of TPHg and benzene are at moderate levels. <br /> TPHg and benzene in off-site wells MW-6, MW-7, MW-8, and MW-9 are currently at <br /> moderate to low concentrations and show a stable or decreasing trend. Off-site wells <br /> MW-10,MW-11,and MW-12 have low to non-detect TPHg and benzene concentrations. <br /> XXXXX(XX) 3 CONESTOGA-ROVERS&ASSOCIATES <br />