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COMPUTATION SHEET <br /> OJECT TITLE Safeway Stockton - 1111 Navy Drive PROJECT NO 22794-100 001 <br /> SCRIPTION Mass of Petroleum Hydrocarbons in Sod &Groundwater SHEET 1 OF 4 <br /> PREP BY DATE CHKD BY DATE <br /> Mass in Sod <br /> These calculations present the total mass of petroleum hydrocarbons as diesel in soil The data set <br /> includes analytical results for UST cavity soil samples and exploratory boring sod samples <br /> Isoconcentration plots of the analytical data were prepared for depths of 12 to 20 feet and 20 to 30 feet <br /> The area enclosed by the respective isoconcentration lines was determined using a planimeter <br /> Sod types encountered during drilling include sand (SP) and silt to clayey silt(ML) An average bulk density value <br /> types of 100 pcf were used in the calculations The average concentration enclosed within the isoconcentation <br /> contour was used <br /> Assumptions concentrations within isoconcentration line are assumed constant <br /> the concentration does not vary with depth <br /> average of detected concentrations are used in the calculations <br /> Planimeter Data <br /> Depth Interval Contour Line Area (ft2) Volume (ft3) Corr Vol (ft3) <br /> 12 to 20 ft TPHD 1,000 ppm 140 1120 1120 <br /> 100 ppm 575 4600 3480 <br /> 10 ppm 2400 19200 14600 <br /> 20 to 30 ft TPHD 1,000 ppm 1480 14800 <br /> 100 ppm 2850 28500 13700 <br /> r <br /> Equation ',-,Mass of TPHD volume of sod X soil density_X pounds TPHD/pound of soil <br /> Mass of benzene =volume of soil X sod density X pounds benzene/pound of sod <br /> corrected volume subtracts the area enclosed within the 1,000 ppm contour from the <br /> are enclosed within the 100 ppm contour, etc , to prevent estimating the mass twice <br /> H,/exceldat/arco/2076calc As <br />