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1 - <br />' APPENDIX A <br /> • CALCULATED MASS OF MTBE M SOIL <br /> I Bogettz's Orchard Service Station <br /> 2393 East Highway 132, Vernalis, Cahfornaa <br />' E 1 ESTIMATED MASS OF MTBE REMAINING IN SOIL <br />' Calculation of the mass of MTBE remaining in soil is based on assumptions of average <br /> concentrations of analytical results for soil samples collected from underground storage tank(UST) <br /> hand samples and soil borings between 1999 and 2002 The estimated areas of MTBE-impacted soil <br /> are illustrated on Figure 5 The assumptions for the mass calculations are based on analytical data, <br /> result and findings of site investigation reports, and field observations <br />' Investigation findings indicate that the majority of MTBE-impact to soil is located in the area <br /> beneath the north end ofthe westernmost dispenser island at an interval of approximately 2 to 17 feet <br /> bsg,and in the area beneath the southern end of UST#2 and UST#3 at an interval of approximately <br /> 2 to 17 feet bsg (Figures 3 and 4) The calculation for mass as as follows <br /> Mass = (Area) x (Thickness) x (Concentration) <br /> I Estimated Mass of MTBE in D=enser Island Soil Plume <br /> Assumptions <br /> • Average area, thickness and concentration of MTBE inside the 1 0 mg/kg isoconcentration <br /> I contour line are 117 4 W, 5 0 feet and 1 85 mg/kg, respectively <br /> ' Sxf 5 'r � S -�� '3 <br /> • Average area, thickness and concentration of MTBE between the 10 mg/kg and 0 1 mg/kg <br /> asoconcentrahon contour lanes are 298 W, 10 feet and 0 5 mg/kg, respectively <br /> • Average area, thickness and concentration of MTBE between the 0 1 mg/kg and 0 01 mg/kg <br /> asoconcentration contour lines are 681 fl, 15 feet and 0 06 mg/kg, respectively <br /> e Average weight of soil 56 625 kg/fI.3 (per unit volume) <br /> Calculations <br /> 1) 117 4 ft2 x 5 ft x 185 mg/kg x 56 625 kg/ft X lkg/l OX 106 mg= 0 061 kg <br /> 2) [298-117 4] ft2 X 10 ft x 0 5 mg/kg x 56 625 kg/f13 x lkg/l Ox 106 mg = 0 051 kg <br /> 3) [681-298] ft2 X 15 ft x 0 06 mg/kg x 56 625 kg/ft3 X 1kg/1 Ox 106 Mg= 0 020 kg <br /> IEstimated mass of MTBE in the dispenser disp p g plume= 0 13 k or 0 29 lbs <br /> Advanced GeoEnvironmental,Inc <br /> I <br />