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I ' 21 August 2002 • AGE-NC Project No 95-0130 Page 5 of 6 • The only detection of dissolved TBA was in the sample collected from well MW-5,however, ' TBA was previously detected at wells MW-1,MW-2,MW-3,VW-1 C,VW-2A,VW-213 and VW-3A suggesting a significant TBA-impact to ground water at the site • EDB was detected in samples collected from wells VW-1B and VW-IC,however,EDB was previously detected at wells MW-7B, VW-2A and VW-2B suggesting a significant EDB- impact to ground water at the site • The high concentrations ofpetroleum hydrocarbons detected in samples collected from wells MW-6 (A, B and C), MW-7B, VW-1 (B and C), VW-2 (A and B) and VW-3 (A and B) ' indicate that these wells are within or near the dissolved petroleum hydrocarbon"core area" of the plume (Figures 4 and 5) • The lateral extent of the dissolved petroleum hydrocarbon plume is not known toward the Inorthwest, north, northeast, east and southeast of the area bound by wells MW-1 through VW-3 (Figures 4 and 5), the vertical extent is not known in any area lie 5.0. RECOMMENDATIONS A Feasibility Studies and Monitoring Well Installation Work Plan was submitted to the EHD on 11 March 2002 and approved by the EHD by letter on 17 April 2002,however, the UST Cleanup Fund Ionly approved a portion of the work plan including installation of one on-site ground water monitoring well(MW-8)and five off-site wells(MW-9 through MW-13) Therefore,AGE is in the process of contacting property owners to the north,northeast and east in order to gain off-site access Thereafter, a signed access agreement by the above respective property owner's will be submitted to the EHD during the permitting process IA Corrective Action Plan was prepared by AGE on 20 March 1996 for soil vapor extraction(SVE) and in-situ air spargmg(IAS)and was approved by the EHD by letter on 26 October 1996 However, the CAP was prepared prior to investigation of MTBE, 1,2-DCA,EDB and TBA at the site and prior to investigation of the vertical extent of petroleum-impacted ground water Therefore, AGE recommends that a feasibility study report be prepared to re-evaluate remediation alternatives for the I site Due to 1) significantly high concentrations of contaminants(I e MTBE and benzene) encountered I at the site, 2) the high mobility of MTBE dissolved in ground water and 3) a recent trend of increasing MTBE concentrations eastward towards 102 South Wilson Way(Roek Property), AGE recommends that a ground water interim remediation work plan be implemented(i e ground pump- and-treat) at the site to inhibit further off-site migration of the fuel-impacted ground water plume until a full scale remediation system can be installed Advanced GeoEnviron mental,Inc I