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RISC Manual Version 4 0 <br /> 71 = fraction of foundation that is cracks [cm2/cm2} <br /> The effective diffusion coefficient in each zone is calculated using the Millington- <br /> Quirk relationship(Millington and Quirk, 1961) <br /> 0 333 D 333 <br /> D = D of �, water Owl (E-4) <br /> e,, .,, Q 2 K Z <br /> T/ H Tr <br /> where <br /> Deft, = effective gaseous diffusion coefficient in zone i [cm2/s} <br /> Ba, = air-filled porosity in zone i [cm3 of air/cm3 total soil <br /> volume] <br /> Bw, = water-filled porosity in zone i [cm3 of water/cm3 total soil <br /> volume] <br /> $T = total porosity in zone i [cm3 pores/cm3 total soil volume] <br /> Da„ = gaseous diffusion coefficient [cm2/s] <br /> • Dwarer, = liquid diffusion coefficient [cm2/s] <br /> KH = Henry's Law constant[(mg/1)/(mg/l)] <br /> E.4.2 Moisture Content - <br /> The moisture content in the four zones (capillary fnnge, vadose zone, lens and <br /> building foundation) are explicitly specified for this model (unlike the Vadose Zone <br /> model, Appendix A) It is assumed that the region of the vadose zone under a <br /> building has no infiltration rate, therefore the moisture content cannot be calculated <br /> using the van Genuchten approach (discussed in Appendix A) The soil beneath the <br /> building is expected to have some moisture content that depends on the soil type and <br /> moisture content of adjacent soil <br /> E.4 3`,Concentration in the Building - ti <br /> The total mass flux of contaminant entering the building is estimated from <br /> E = F A (E-5) <br /> E-6 <br />