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r.. Report:Groundwater-quality Monitoring—October 27,2004, 7500 West Eleventh Street, Tracy,CA- Page 19 7.0 RECOMMENDATIONS SJC recommends that to initiate a program designed to bring the site to "closure," the program of activities described below should be initiated, subject to the approval of the SJCEHD. The recommendations are consistent with the recommendations made at the time we prepared our report for the July 2004 groundwater-quality monitoring round (The San Joaquin Company Inc. 2004a) and the applicable sections of the Work Plan for Refined Plume Definition and Management of Floating Product at Former Fueling Station, 7500 West Eleventh Street, Tracy, California, (The San Joaquin Company 2003a)that were previously approved by the SJCEHD. 7.1 Evaluation of Natural Attenuation of Plumes of Affected Groundwater To evaluate whether the hydrogeologic and geochemical conditions necessary to sustain the intrinsic, natural attenuation and remediation, including bioremediation, of the components of fuel hydrocarbons present in the plumes of affected groundwater are as active as they appear to be currently at the site, a round of groundwater-quality monitoring should be conducted that is designed to measure the pertinent groundwater parameters as well as the remaining concentration of fuel hydrocarbons. The details of the groundwater-quality monitoring should be based on the applicable elements of the ,., recommendations made in Section 14 of SJC's December 2003 Work Plan, previously approved by the SJCEHD. ..+� Depending upon the details of a final analysis plan, samples would be recovered from the groundwater beneath the site and would be analyzed for: alkalinity, total organic carbon, general minerals, ferrous iron(field filtered), manganese,nitrate, sulfate, methane, carbon dioxide and biochemical oxygen demand. For the purposes of this specific groundwater- quality monitoring round, samples would be recovered from all wells screened in the shallow aquifers beneath the site. That includes the wells that were previously used only �- for the purpose of detecting any LNAPL that may have been present. The proposed groundwater-quality monitoring round should be conducted in February w. 2005, at which time the depth to groundwater beneath the site will be close to its annual minimum and oxygen in groundwater due to the infiltration of imported irrigation water will also be at a minimum. That arrangement will provide for conservative estimate of the rate of intrinsic remediation at the site. 7.2 Closure of Groundwater-quality Monitoring Wells After the round of groundwater-quality monitoring proposed for February 2005 has been conducted, Monitoring Wells MW-3A, MW-3B and MW-12A should be `i closed under the permit and oversight of the SJCEHD. SJC