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• A <br /> COMPUTATION SHEET <br /> � <br /> OJECT TITLE ARCO Service Station 6100 PROJECT NO 20805-152 008 <br /> 'SCRIPTION Mass of Petroleum Hydrocarbons in Soil SHEET 1 OF _ <br /> PREP BY MC DATE Jul 17 98 CHKD BY DATE <br /> These calculations present the total mass of TPHG in soil The data set contains <br /> analytical results for UST cavity and piping trench soil samples and exploratory boring soil samples <br /> Isoconcentration plots of the analytical data were prepared for depths of 10 to 25 feet bgs, <br /> 26 to 45 feet bgs, 46 to 65 feet bgs, 66 to 85 feet bgs, and 85 to 115 feet bgs <br /> The area enclosed by the respective isoconcentration lines was determined using a planimeter <br /> Soil types encountered during drilling include fine grained sand (SP) silty sand (SM), salt (ML), and clay (CL) <br /> An average bulk density value for the soil types encountered of 110 pcf was used in the calculations <br /> Assumptions concentrations within isoconcentrat+on lane are assumed constant <br /> the average of detected concentrations within the interval was used <br /> the concentration does not vary with depth <br /> Planimeter Data <br /> Depth Interval Contour Line Area (ft2) Volume (ft3) Corr Vol (ft3) <br /> TPHG - 10 to 25 ft 1000 2628 39420 <br /> 100 7375 110625 71205 <br /> 10 11922 178830 68205 <br /> 1 15117 226755 47925 <br /> TPHG - 26 to 45 ft 10000 822 16440 <br /> 1000 4607 92140 75700 <br /> 100 7806 156120 63980 <br /> 10 12390 247800 91680 <br /> 1 16300 326000 78200 <br /> TPHG - 46 to 65 ft 10000 590 11800 <br /> 1000 4800 96000 84200 <br /> 100 7019 140380 44380 <br /> 10 10635 212700 72320 <br /> 1 17329 346580 133880 <br /> TPHG - 66 to 85 ft 1000 1255 25100 <br /> 100 2290 45800 20700 <br /> 10 3734 74680 28880 <br /> 1 4766 95320 20640 <br /> TPHG - 86 to 115 1 208 6240 <br /> Equation Mass of hydrocarbon = volume of soil X soil density X pounds hydrocarbon/pound of soil (a, ) <br /> corrected volume subtracts the area enclosed within the 100 ppm contour from the —x--Q X <br /> are enclosed within the 10 ppm contour, etc , to prevent estimating the mass twice <br /> K/exceldat/arco/6100calc As <br />