Ill. Admin. Code tit. 35, pt. 742, subpt. L, app C, tbl. M
Symbol | Parameter | Units | Source | Tier 1 or Calculated Value |
AB | Surface area of enclosed space at or below grade | cm2 | Equation J&E 12a or 12b, Appendix C, Table L | Residential = 1 x 106 Industrial/Commercial = 4.0 x 106 |
Acrack | Area of total cracks | cm2 | Equation J&E 14, Appendix C, Table L | Calculated Value |
ATc | Averaging time for carcinogens | year | SSL, May 1996 | 70 |
ATnc | Averaging time for noncarcinogens | year | ATnc = ED | Residential = 30 Industrial/Commercial = 25 |
Cvsat | Soil vapor saturation limit | mg/m3-air | Equation J&E 5, Appendix C, Table L | Chemical-Specific or Calculated Value |
Dcrackeff | Effective diffusion coefficient through the cracks | cm2/s | Equation J&E 15, Appendix C, Table L | Calculated Value |
Di | Diffusivity in air | cm2/s | Appendix C, Table E | Chemical-Specific |
Dieff | Effective diffusion coefficient for each soil layer | cm2/s | Equation J&E 11, Appendix C, Table L | Calculated Value |
Dsource | Distance from ground surface to top of contamination | cm | Field Measurement | Soil Gas Contamination = 152.4 Groundwater Contamination = 304.8 Site-Specific |
DTeff | Total overall effective diffusion coefficient | cm2/s | Equation J&E 9a, Appendix C, Table L | Calculated Value |
Dw | Diffusivity in water | cm2/s | Appendix C, Table E | Chemical-Specific |
ED | Exposure duration | year | Residential: SSL, May 1996 Industrial/Commercial: SSL 2002 | Residential = 30 Industrial/Commercial = 25 |
EF | Exposure frequency | day/year | Residential: SSL, May 1996 Industrial/Commercial: SSL 2002 | Residential = 350 Industrial/ Commercial = 250 |
ER | Air exchange rate | exchanges per hour | Illinois EPA | Residential = 0.53 Industrial/ Commercial = 0.93 |
foc | Fraction organic carbon content | g/g | SSL, May 1996, or Field Measurement Appendix C, Table F | 0.002 or Site-Specific |
HB | Height of building | cm | Illinois EPA | Slab-on-Grade Residential = 244 Industrial/ Commercial = 305 or Site-Specific in Tier 3 Basement Residential = 427 Industrial/ Commercial = 488 or Site-Specific in Tier 3 |
H'TS | Dimensionless Henry's law constant at the system (soil) temperature 13C | unitless | Appendix C, Table E | Chemical-Specific |
LB | Length of building | cm | Illinois EPA | Residential = 1000 Industrial/Commercial = 2000 or Site-Specific in Tier 3 |
Lcrack | Slab thickness | cm | USEPA, Users Guide, 2004 | 10 |
LF | Distance from ground surface to bottom of slab | cm | USEPA, Users Guide, 2004 | 10 (slab on grade) 200 (basement) |
Li | Thickness of soil layer i | cm | Field Measurement for Capillary Fringe, USEPA, 2004 | Site-Specific For Capillary Fringe, 37.5 cm |
LT | Distance from bottom of slab to top of contamination | cm | Field Measurement or Equation J&E 10, Appendix C, Table L | 142.4 or Site-Specific |
MW | Molecular weight | g/mole | Illinois EPA | Chemical-Specific |
n | Total number of layers of different types of soil vapors migrate through from source to building (if source is groundwater, include a capillary fringe layer of 37.5 cm as one of the layers) | unitless | Field Measurement | Site-Specific |
P | Vapor Pressure | atm | Appendix C, Table E | Chemical-Specific |
Qbldg | Building ventilation rate | cm3/s | Equation J&E 13, Appendix C, Table L | Slab-on-Grade Residential = 3.59 x 104 Industrial/ Commercial = 3.15 x 105 or Site-Specific in Tier 3 Basement Residential = 6.28 x 104 Industrial/Commercial = 5.04 x 105 or Site-Specific in Tier 3 |
Qsoil | Volumetric flow rate of soil gas into the enclosed space | cm3/s | USEPA, Users Guide for Evaluating Subsurface Vapor Intrusion into Buildings, 2004 | If LT is less than 5 feet (152 cm), Qsoil equals 83.33. If LT is 5 feet (152 cm) or greater, Qsoil equals zero. An input value of zero requires an institutional control. See Section 742.505(b) and (c). |
R | Ideal gas constant | atm-L/mol-K | USEPA, Users Guide, 2004 | 0.08206 |
RfC | Reference concentration | µg/m3 | Illinois EPA: http://www.epa.state.il.us/land/taco/toxicity-values.xl | Toxicological-Specific |
ROgw | Groundwater remediation objective | mg/L | Appendix B, Table E, or Equation J&E 6, Appendix C, Table L | Chemical-Specific or Calculated Value |
ROindoor-air | Indoor air remediation objective | mg/m3 | Equations J&E 1 and 2, Appendix C, Table L | Calculated Value |
ROsoilgas | Soil gas remediation objective | mg/m3 | Equation J&E 4, Appendix C, Table L | Calculated Value |
S | Solubility in water | mg/L | Appendix C, Table E | Chemical-Specific |
T | Temperature | °K | USEPA, Users Guide, 2004 | 286 (converted from 13oC) |
THQ | Target hazard quotient for a chemical | unitless | SSL, May 1996 | 1 |
TR | Target risk or the increased chance of developing cancer over a lifetime due to exposure to a chemical | unitless | SSL, May 1996 | Residential = 10-6 at the point of human exposure Industrial/Commercial = 10-6 at the point of human exposure |
URF | Unit risk factor | (µg/m3)-1 | Illinois EPA: http://www.epa.state.il.us/land/taco/toxicity-values.xl | Toxicological- Specific |
w | Floor-wall seam gap | cm | USEPA, Users Guide, 2004 | 0.1 |
W | Moisture content | g of water/g of soil | Field Measurement, Appendix C, Table F | Site-Specific |
WB | Width of building | cm | Illinois EPA | Residential = 1000 Industrial/ Commercial = 2000 or Site-Specific in Tier 3 |
[ALPHA] | Attenuation factor | unitless | Equations J&E 7 or 8, Appendix C, Table L | Site-Specific |
[THETA]a | Air-filled soil porosity | cm3/cm3 | SSL, May 1996 or Equation J&E 18, Appendix C, Table L | 0.28 or Calculated Value |
[THETA]a,crack | Air-filled porosity for soil in cracks | cm3/cm3 | SSL, May 1996 or Equation J&E 18, Appendix C, Table L | 0.13 |
[THETA]a,i | Air-filled porosity of soil layer i | cm3/cm3 | SSL, May 1996 or Equation J&E 18, Appendix C, Table L | 0.13 or Calculated Value For capillary fringe, [THETA]a,i = 0.1 [THETA]T,i |
[THETA]T,crack | Total porosity for soil in cracks | cm3/cm3 | SSL, May 1996 or Equation J&E 16, Appendix C, Table L | 0.43 |
[THETA]T,i | Total porosity of soil layer i | cm3/cm3 | SSL, May 1996 or Equation J&E 16, Appendix C, Table L | 0.43 or Calculated Value |
[THETA]w | Water-filled soil porosity | cm3/cm3 | SSL, May 1996 or Equation J&E 17, Appendix C, Table L | 0.15 or Calculated Value |
[THETA]w,crack | Water-filled porosity for soil in cracks | cm3/cm3 | SSL, May 1996 or Equation J&E 17, Appendix C, Table L | 0.15 |
[THETA]w,i | Water-filled porosity of soil layer i | cm3/cm3 | SSL, May 1996 or Equation J&E 17, Appendix C, Table L For capillary fringe, US EPA, Users Guide 2004 | 0.15 or Calculated Value For capillary fringe = 0.375 or 0.9 qT,i |
[THETA]b | Dry soil bulk density | g/cm3 | SSL, May 1996 or Field Measurement, Appendix C, Table F | 1.5 or Calculated Value |
[THETA]s,i | Soil particle density | g/cm3 | SSL, May 1996 or Field Measurement, Appendix C, Table F | 2.65 or Calculated Value |
[THETA]w | Density of water | g/cm3 | Illinois EPA | 1 |
Ill. Admin. Code tit. 35, pt. 742, subpt. L, app C, tbl. M