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1 r cleologtoI TgAX&r/Ac. Page 4 Sinclair Trucking Project No.: 1030.2 November 1, 2005 After review of the May 19, 2004 SJCEHD letter, GTI met with Mr. and Mrs. Sinclair to determine the course of remediation for the site. The driving factor for Mr. and Mrs. Sinclair ' is time due to property issues with family members, making accelerated remediation at the site essential. It was decided during the meeting that excavation would be the remedial alternative that best fits the needs for the ST site. ' GTI prepared and submitted the Addendum to the Site c P P Conceptual Model, Feasibility Study and Corrective Action Plan on July 12, 2004. In a letter dated August 3, 2004, Ms Duncan ' requested some modifications to the proposed corrective action plan. GTI prepared and submitted the final Remedial Action Work Plan dated September 20, 2004. In a letter dated October 4, 2004, Ms Duncan approved the proposed remedial action plan with minor caveats. ' The State Water Resources Control Board SWRCB denied most of the { ) costs associated with the work in a letter dated November 8, 2004. In a phone conversation on December 16, 2004, Mr. Trommer (SWRCB) stated he felt it was a groundwater problem and not a soil contamination problem. Mr. Trommer stated that if there was obvious soil contamination a reasonable amount of soil could be removed, but he thought 1,500 cubic yards was excessive. Mr. Trommer placed a written 150 cubic yard and a verbal 300 cubic yard limitation on soil excavation. Details of the soil excavation and monitoring well installation activities are discussed in the GTI Remedial Action Report dated August 11, 2005. Ms Duncan directed a recalculation of the contaminant mass at the site, both before and after the remediation activities, and that all ' available site data be used in the calculations. The following revised remedial action report addresses the mass estimate calculations. 2.0 MASS ESTIMATE CALCULATIONS ' 2.1 Original Mass Estimate Calculations Original mass balance calculations, discussed in GTI's: Initial Site Conceptual Model dated ' June 18, 2003 indicated approximately 3,400 pounds of TPH-G was bound to the soil at the Sinclair site. The initial estimates were an interpolation of available data based on soil samples collected prior to November 2003. The interpolation was limited to only six data ' points above 10 feet bgs and two data points below 10 feet bgs. The limited number of data points made software generated contours less dependable. Ten GeoProbe borings and two soil borings were advanced during November 2003 and the results are discussed in the following section. Table 2 of Appendix A summarizes all soil sample results collected at the site. Table 3 summarizes the original soil mass estimate calculations. Figure 3 shows all subsurface soil sample locations collected to date.