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I " 01 October 2004 AGE-NC Project No 95-0173 Page 9of10 I5.0. RECOMMENDATIONS Based upon second quarter 2004 data collected from the site, AGE recommends • Continued quarterly ground water monitoring and sampling at the site,to reduce unnecessary sampling/analytical costs AGE recommends removal of wells with four consecutive events I with no detection of contamination from the sampling program (MW-7, MW-8, MW-10, MW-11 and MW-12) Ground water sampling of the remaining wells should continue quarterly to monitor progress of the SVE and IAS remediation system ' • Continued operation of the on-site SVE and IAS remediation system, however,to optimize the effective radius of influence In the `core' area of the plume, AGE recommends only extraction from SVE wells VW-1, VW-2 and alternating sparging pressure to wells AW-1 A and AW-1B Remediation progress will be re-evaluated on a quarterly basis ' Aground water aquifer pumping test was performed at the site in July 2003 to evaluate groundwater `pump-and-treat' as a potential remediation option for ground water clean-up at the site Based on the pumping test results,AGE concluded that a pump-and-treat remediation system could effectively 10 stabilize the ground water plume and inhibit further migration of petroleum-impacted ground water off-site Furthermore,AGE recommended augmenting the existing SVE and IAS remediation system at the site with a pump-and-treat remediation system(Ground WaterAquifer Pumping Test Report- July 2003, dated 04 February 2004) ' However,between the months of December 2003 and June 2004,the SVE/IAS remediation network at the site was reconfigured to utilize only remediation wells (VW-1 through VW-4 and AW-213) within the core area of the dissolved plume Thereafter, the reconfigured SVE/IAS remediation I system appeared to have a greater efficiency in removal of petroleum hydrocarbons in both soil-gas vapor and in ground water As a result, ozone sparging should also be evaluated prior to implementing a ground water pump-and-treat remediation system If applicable, ozone sparging ' could be a more efficient remediation technology as compared with ground water pump-and-treat Prior to implementation of an alternative ground water remediation system, one additional ground water monitoring well should be installed off-site and east-northeast of well MW-4, the well should be designed to assess the downgradient and vertical migration of the petroleum-impact Ideally,the well should be placed approximately 50 feet off-site towards the northeast, and located In the small parking area owned by the adjacent apartment complex (Figure 2) If a monitoring well access agreement cannot be reached with the apartment complex property owners, then the well could be moved westward and onto the adjacent alley (City of Stockton right-of-way) Installation of this additional well will be used to evaluate whether or not an off-site remediation well is necessary Advanced GeoEnvironmental,Inc