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Corrective Action Plan Page 43 even when the preponderance of the contaminant load has been removed by excavating contaminated soil For planning purposes, it has been assumed that groundwater-quality monitoring will have to be continued for ten years following completion of soil remediation Based on the considerations outlined above, it is estimated that active remediation of the site will be complete within eight months from the time funding for the remediation program becomes available and that it will be possible to obtain closure of the property as the site of an unauthorized release of fuel hydrocarbons within ten years of completion of the active phases of remediation However, the actual time required before formal closure can be obtained will depend on the rates at which the concentration of contaminants in the groundwater are reduced to less than those of regulatory concern SITE CLOSURE As groundwater-quality data are accumulated, the distribution and concentrations of components of fuel hydrocarbons in the affected area and their rate of change will be periodically reviewed If analyses of samples from four consecutive, quarterly sampling rounds consistently demonstrate that the groundwater is free of detectable concentrations of the analytes of concern, application will be made to the SJCPHS and the CRWQCB for closure of the property as a site of an unauthorized release of fuel hydrocarbons If, after an extended period of monitoring, the concentration of contaminants have fallen to very low levels but some detectable traces remain, the threat that any residual components of fuel hydrocarbons pose to the beneficial uses (if any) of the shallow groundwater beneath the site will be evaluated in the context of the CRWQCB's Basin Plan criteria If the results show that the residual concentrations are less than those judged to be significant, an application will be made the Board for closure of the property based on site-specific criteria COST ESTIMATES An engineer's estimate was developed for the complete cost of the remediation program proposed when the original Corrective Action Plan (Ref 14) for the subject site was prepared That estimate (Ref 15) included the estimated cost of site preparation, installation and operation of groundwater recovery wells and a semi-permanent treatment system that would operate for an estimated four years with an associated program of groundwater-quality monitoring of the same duration Similarly, an engineer's cost estimate (Ref 18) has been prepared for the remediation program described in this amended corrective action plan This estimate includes the cost of demolition and site preparation, excavation of an estimated 1,100 in-situ cubic yard of contaminated soil, treatment and discharge of some 300,000 gallons of contaminated groundwater pumped from the remedial excavation, back filling of the remedial