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' DRAFT <br /> 1 <br /> 1 nT = Total soil porosity (cm3)/cm3 soil), ASTM E 1739-95 <br /> Dair X n3.33 Dwat x n3.33 <br /> Def( = as + ws \ 5) <br /> DS nT H X nT 1- <br /> where: <br /> D 5f = Effective diffusion coefficient in soil based on vapor phase <br /> concentration (cm2/sec) <br /> Dair = Diffusivity in air (CM2/sec), chemical-specific <br /> n,, = Volumetric air content in vadose zone soil (cm3 air)/cm3 soil), <br /> ASTM E 1739-95 <br /> Dwat = Diffusivity in water(cm2/sec), chemical-specific <br /> nws = Volumetric water content in vadose zone soil (cm3 water)/cm3 <br /> soil), ASTM E 1739-95 <br /> H = Henry's Law constant, (cm3-H20/cm3-air), chemical-specific <br /> nT - Total soil porosity (cm3)/cm3 soil), ASTM E 1739-95 <br /> The values for each of the equation terms used for each modeling case are presented in <br /> Table 10. The chemical-specific volatilization factors for soil and groundwater are <br /> presented in Tables 11 and 12,respectively. In addition to the specific assumptions <br /> presented in Table 10, the volatilization factors are also based on the following <br /> ' conservative generic assumptions: <br /> 1 SOMA 99-2218 9 12/10/99 <br />