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Vadose Zone Model <br /> v= 9 (A-29) <br /> aN <br /> where <br /> v = seepage velocity(actual water flowrate through vadose <br /> zone) [cm/d] <br /> — <br /> q infiltration rate(recharge rate to groundwater) [cm/d] <br /> aw = volumetric water content or water-filled porosity (cm3 <br /> ' water/cm3 soil] <br /> ' The seepage velocity, u, is the average rate of flow that the model uses for the water <br /> percolating through the vadose zone <br /> The water content for the lens may differ from the vadose zone and is also calculated <br /> from the same equations as presented above using the lens properties The values of <br /> the estimated moisture contents are presented in the RISC model output The <br /> moisture content is not calculated by the volatilization models (Appendices D, E, J <br /> and K) since it is assumed that for soils under a house or building, the infiltration rate <br /> lie is close to zero In these models the user is requested to specify the average moisture <br /> content in the vadose zone If the vadose zone is subject to infiltration, the above <br /> ' algorithm may be run using the vadose zone model to estimate likely ranges of <br /> moisture content The moisture content can then be entered in the air models <br /> Equations A-5 through A-7 are used to calculate the dissolved phase concentrations in <br /> the unsaturated zone from the bottom of the source zone to the groundwater aquifer <br /> A 6.1 Mass Loading To Groundwater <br /> The mass flux of contaminant at the water table is calculated using Equation A-5 <br /> solved at the water table multiplied by the infiltration rate <br /> A-17 <br />