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i <br /> The saturated zone is assumed to,be homogeneous and.isotropic in terms of its physical <br /> properties (Porosi , bulk density, etc.). Time-varying ringmass rates for the four organic <br /> � <br /> chemicals simulated to be released at the site were used. The time-varying mass rates <br /> were calculated using Jury the Ju unsaturated zone model. <br /> > Data requirements for AT123D are presented in Table 4-3. If site specific data were not <br /> available, then input values were used that would tend to overpredict chemical transport <br /> times. For example the hydraulic conductivity and porosityi were selected for a <br /> permeable silt media instead of clay. Physical chemical properties of the chemicals of <br /> concern used in the fate and transport modeling are presented in Table 4-4. No <br /> naturally occurring degradation of the organic chemicals was assumed to occur in the <br /> unsaturated or saturated zone modeling. <br /> Modeling results for AT123D and Jury Behavior Assessment model are presented in <br /> Appendix A. <br /> 4.4.3.2 VOC Concentrations in Air During Showering <br /> T Potential exposure to hypothetical future residents to volatile chemicals in air, as a result <br /> of volatilization from groundwater during showering was evaluated. Daily inhalation <br /> I <br /> during showering is computed as a function of the concentration of volatiles in the <br /> shower air, the inhalation rate, and the duration of the shower: <br /> -k <br /> DI = Cah IH ET Rah /BW <br /> where: <br /> DI = daily absorbed dose from inhalation while showering (mg/kg-d) <br /> Cah = concentration of chemical in shower air (mg/m3) <br /> IH = inhalation rate during showering ('m3/hr) <br /> BW = body weight (kg) <br /> Rah = chemical specific bioavailability for inhalation <br /> I <br /> i <br /> S:\LDC\YELLO.Rn May 4, 1995 4-10 <br /> y <br />