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Dear Ms . Page 5 of 7 <br /> 40 <br /> • Since July 1995 and up to present time, extensive effort has been invested <br /> in the assessment of contamination plumes in the soil and groundwater. <br /> There are currently 27 groundwater monitoring wells: 25 on site and 2 <br /> across the street east of the property. <br /> • Groundwater-dissolve MTBE has migrated west beyond the western <br /> property line. SJCEHD is concerned about migration of MTBE in the <br /> direction of domestic water wells in the neighborhood. <br /> • To date, over $800,000 has been expended by FTI on the corrective <br /> action. Claims were presented to California UST Cleanup Fund; <br /> $626,829 has been reimbursed and balance is awaiting resolution of the <br /> cash flow at USTCF. FTI retained AA&A to manage the corrective <br /> action to closure in the quickest, most cost effective route. <br /> DECISIONS: <br /> In agreement with SJCEHD: <br /> 1. Site Conceptual Model (SCM) is a pre-requisite for effective design of all <br /> corrective action; however, there has been no SCM done for the site yet. <br /> AA&A will proceed immediately in the formulation of an SCM. <br /> 2. For SCM, AA&A must review all records of actions taken. SJCEHD <br /> maintains electronic records of all case files and will provide same to <br /> AA&A upon request. <br /> 3. Exposure Pathway Analysis is critical for the establishment of SCM. The <br /> Analysis requires geological and contaminant data foot by foot in the <br /> capillary fringe and saturated smear zones. This data is gained through <br /> continuous core sampling. AA&A will formulate a workplan for <br /> Exposure Pathway Analysis. <br /> 4. Corrective Action strategy for the site will implement the Zone <br /> Remediation Concept where the plume is viewed as composed of <br /> components in three zones: <br /> • Zone 1: Source, where most (90%) of the contaminant mass <br /> resides: in the unsaturated and saturated soil phases. This zone <br /> requires the most aggressive and quickest correction. <br /> • Zone 2: Residual, where most of the remainder mass (10%) <br /> resides: in the saturated and capillary zones surrounding the <br /> source zone. This zone is usually treated by vapor extraction, <br /> multi-phase extraction and various in-situ oxidation techniques <br /> down to target cleanup levels established on the basis of risk. <br /> • Zone 3: Farther, downgradient from source, frequently off-site, <br /> across streets, under neighborhoods. This zone is left for <br /> natural attenuation. <br /> 12/14/2009 <br />