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09 January 2003 AGE-NC Project No. 95-0114 Page 8 of 9 of 65 feet bsg. However, the highest concentrations of PCE, TCE and cis 1,2-DCE was detected in soil samples collected from off-site monitoring well MW-10. • The vertical extent, and lateral extent towards the northeast and southeast, of dissolved TPH-ss have not been defined. • The lateral extent of dissolved PCE and TCE concentrations has been defined to concentrations below 20 gg/l (CPT6-50); the vertical extent has been defined to concentrations below 5.0 µg11, which are within their established MCLs. The lateral extent of the dissolved cis 1,2-DCE plume has been defined to on-site boring SB2 and off-site boring CPT4, monitoring well MW-10 and CPT5 (Figure 4); the vertical extent has been defined, at approximately 80 feet bsg. The lateral and vertical extent of vinyl chloride has been defined (Figures 5, 6 and 7). • Dissolved 1,2-DCA was detected for the first time in the off-site CPT samples CPT3-110, CPT4-110,CPT5-120 and CPT6-120,which were collected from the deepest hydrologic unit (HU6);the 1,2-DCA concentrations were all above the DHS's MCL for drinking water. The subsurface extent of this compound has not been defined (Figures 4 and 6). 5.0. RECOMMENDATIONS Based on the findings from this investigation, AGE recommends: • Continued quarterly ground water monitoring; the next monitoring event is scheduled for January 2003. • Install an additional monitoring well northeast of CPT6 (Figure 2) to determine the lateral extent of PCE, TCE, cis 1,2-DCE and 1,2-DCA. • Install additional multi-level monitoring wells in the area of Monroe Street (Figure 2) to determine the vertical as well as southeast boundaries of impacted ground water, and any impact to the contaminant plumes (e.g., 1,2-DCA) from the neighboring site at 244 West Harding Way that is currently being environmentally assessed. Advanced GeoEnvironmental,Inc.