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Geolagkal Techaks Inc Page 11 ' Groundwater Monitoring Report • Project No 425 2 November 8,2005 ' E 4.0 CONCLUSIONS AND RECOMMENDATIONS ' Conclusions 1 BTEX and TPH-G constituents have peaked in MW-1 and MW-2 and are showing ' decreasing concentrations This is likely due to the plume moving off-site to the north and northeast 2 BTEX and TPH-G constituents have reached MW-8 and are likely to reach MW-7 and MW-6 by early 2006 3 The dominance of upward vertical flow of groundwater may be the primary reason contamination is not impacting Zone C and D or the drinking water aquifer 4 Petroleum hydrocarbon concentrations in the groundwater at the site fluctuate with each monitoring event The residual contamination in soil, up gradient of MW-2, remains a significant source of impact to the groundwater plume 5 Generally the soil and groundwater testing data suggests that the contaminants have spread laterally, but not vertically to any great extent into the deeper aquifer horizons ' This may be due primarily to the upward flow of groundwater observed at this site It is also observed that the groundwater plume does not appear to be continuing to spread laterally down gradient The leading edge seems to be stationary, suggesting that if the high concentrations of contaminants could be further reduced and if oxygen could be introduced into the subsurface, the contaminant plume should collapse 6 The three domestic wells sampled remain non-detect above laboratory reporting limits for ' all analyzed constituents, indicating that the drinking water aquifer has not been impacted ' Recommendations The following recommendations are made ' 1 Continue quarterly groundwater monitoring events 2 Implement scope of work discussed in GTIs Feasibility and In-Situ Remediation Pilot Test Work Plan dated June 14, 2005 and approved by SJCEHD in a letter dated September 16, 2005 (in Progress) i