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APPENDIX E <br /> MTBE & TPH-g-IMPACTED GROUND WATER <br /> VOLUME ASSUMPTIONS AND CALCULATIONS <br /> CALIFORNIA STOP - 2224 Manthey Road, Stockton, California <br /> Assumptions: <br /> The distribution of the average dissolved methyl tertiary butyl ether (MTBE) and total <br /> petroleum hydrocarbons quantified as gasoline (TPH-g) concentrations in the water <br /> table beneath the site can be approximated by the shapes depicted in Figures 8 and <br /> 9; <br /> The effective porosity of soil at the site is estimated to be 35%; <br /> The average and high concentrations from most recent ground water samples <br /> collected from site ground water monitoring wells (Table 3) were used to develop <br /> average and high MTBE and TPH-g mass/volume calculations; <br /> The height of the ground water plumes was determined by averaging the four most <br /> recent ground water monitoring event depth to water data sets (approximately 20 <br /> feet below surface grade [bsg]) and the bottom of the impacted well screens (30 feet <br /> bsg)-- providing for a height of 10 feet (Table 2); <br /> The area of each shape was determined utilizing IntelliCADT`". IntelliCADTm has a <br /> specific function to calculate the area of a selected object. <br /> The volume of the shapes can be calculated by the formula: <br /> V = AREA-H, where "area" is determined through IntelliCadTm and "H" is the <br /> maximum height of the dissolved contamination. Volume calculations are shown on <br /> Figures 8 and 9. <br /> Conversion factors: <br /> 1 ft3 of water = 7.48 gallons <br /> 1 gallon of water = 8.337 lbs/gal <br /> 1 microgram per liter (pg/1) = 0.000000001 grams(g)/milliliter(ml) <br /> *A ml is very nearly equivalent to a cubic centimeter of water, which by <br /> definition equals one gram, this concentration is nearly a unitless number. <br /> 1 gallon of MTBE = 6.19 pounds; 1 gallon of TPH-g = 6.25 pounds <br /> Advanced GeoCnvironmental,Inc. <br />