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r rNotes for Table 2 . --= Parameter was not available r Average Groundwater Temperature--The soil/groundwater temperature is used to correct the Henry's law constant to the specified temperature Shallow groundwater temperatures can be used to approximate subsurface soil temperatures greater than one to two meters below the r ground surface Depth Below Grade to Bottom of Enclosed Space Floor—Enter the depth to the bottom of the floor in contact with the soil The default value for slab-on-grade construction is 15 cm r Depth Below Grade to Water Table—Enter the depth to the top of the water table(i e ,where the pressure head is equal to zero and the pressure is atmospheric) Note The thickness of the capillary zone is calculated based on the SCS sod textural classification above the top of r the water table The depth below grade to the top of the water table minus the thickness of the capillary zone must be greater than the depth below grade to the bottom of the enclosed space floor This means that the top of the capillary zone is always below the floor Vadose Zone SCS Soil Type—The screening-level model accommodates only one soil stratum r above the top of contamination The SCS sod type is used to estimate soil vapor permeability for soil stratum The default SCS sod type is loam (L) The SCS sod types are listed below C= Clay r CL=Clay loam L= Loam LS = Loamy sand r S = Sand SC= Sandy clay SCL= Sandy clay loam SI = Silt r • SIC = Silty clay SICL= Silty clay loam SIL=Silt loam r SL=Sandy loam SCS Soil Type Directly Above Water Table—The SCS sod type directly above the water table is used to estimate the rise(thickness)of the capillary zone The default SCS sod type is silty clay (SIC) r The SCS soil types are listed above Vadose Zone Soil Dry Bulk Density—The screening-level model accommodates only one sod stratum above the top of contamination Enter the depth-averaged soil dry bulk density The default value is 15 g/cm3 is consistent with U S EPA (1996a, 1996b)for subsurface soils r Vadose Zone Soil Total Porosity The screening-level model accommodates only one soil stratum above the top of contamination The default value is 0 43 is consistent with U S EPA(1996a, 1996b)for subsurface soils r Vadose Zone Soil Water-Filled Porosity—The screening-level model accommodates only one soil stratum above the top of contamination The default value is 0 30 is consistent with U S EPA (1996a 1996b)for subsurface soils Averaging Time for Carcinogens—Enter the averaging time for carcinogens in units of years The default value of 70 years is consistent with standard EPA(1996a, 1996b) human health exposure factors Averaging Time for Noncarcinogens—Enter the averaging time for noncarcinogens in units of years I The default value of 25 years is consistent with standard EPA(1996a, 1996b) human health exposure factors Exposure Duration—Enter the exposure duration in units of years The default value of 25 years is consistent with standard EPA(1996a, 1996b) human health exposure factors Exposure Frequency—Enter the exposure frequency in units of daystyr The default value of 250 days/year is consistent with standard EPA(1996a, 1996b) human health exposure factors Unit Risk Factor—Enter the carcinogenic inhalation unit risk factor for benzene in units of(uglm3)`' The default value of 7 5E-06 is consistent with standard EPA(1996a, 1996b) human health exposure factors Reference Concentration—Enter the noncarcinogenic inhalation reference concentration for benzene in units of ug/m3 There was no default value from EPA for benzene for this parameter