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Geological Technics Inc, Page 6 Groundwater Monitoring Report Project No. 989.2 April 25, 2002 4.0 CONCLUSIONS AND RECOMMENDATIONS ' The following conclusions have been drawn from the data generated from this site investigation work: Conclusions 1. The highest levels of BTEX and TPH-gasoline are present in MW-1 & 4, as would be ' expected. ❑ MW-1 is closest to the location of the former UST ❑ MW-4 is the nearest down gradient well to the former UST ' 2. Since MTBE is present only in MW-4, MW-5 and MW-6, and not in the wells near the former USTs, the source is not clear. But it appears not to be the former UST. 3. Since March 1996 very low levels of MTBE have only been detected twice in wells near ' the location of the former UST. According to Wm. J. Hunter & Associates, the MTBE detected in MW-1 during the July 2000 monitoring event is suspect. 4. Changes in TPH-gasoline concentrations are associated with groundwater elevation. ' 5. DIPE, ETBE, TAME, TBA, 1,2 DCA and EDB are not present at this site. Recommendations 1. Further define the lateral extent of the plume: Install three monitoring wells along Oak Street; northwest, north and northeast of the Property. The Work Plan has been approved waiting for Cost Pre Approval. ' 2. Further define the vertical extent of the plume: Install a deep monitoring well near the former the UST. The Work Plan has been approved waiting for Cost Pre Approval. ' 3. Conduct a sensitive receptor survey within a 2000-foot radius of the site for risk evaluation associated with the contamination plume. A work plan proposing this work will be submitted shortly. ' 4. Continue quarterly monitoring to evaluate how the new and existing wells will improve our understanding of the nature and extent of the groundwater contamination plume. S. Discontinue testing for DIPE, ETBE, TAME, TBA, 1,2 DCA and EDB for existing ' monitoring wells.