Symbol

Parameter

Units

Source

Parameter Value(s)

AT

Averaging Time for Noncarcinogens in Ingestion Equation

yr

Residential = 6

Industrial/Commercial = 25

Construction Worker = 0.115

AT

Averaging Time for Noncarcinogens in Inhalation Equation

yr

Residential = 30

Industrial/Commercial = 25

Construction Worker = 0.115

AT_c

Averaging Time for Carcinogens

yr

SSL

70

BW

Body Weight

kg

Residential = 15, noncarcinogens

70, carcinogens

Industrial/Commercial = 70

Construction Worker = 70

C_sat

Soil Saturation Concentration

mg/kg

Appendix A, Table A or Equation S29 in Appendix C, Table A

Chemical-Specific or Calculated Value

C_w

Target Soil Leachate Concentration

mg/L

Equation S18 in Appendix C, Table A

Groundwater Standard, Health Advisory concentration, or Calculated Value

d

Mixing Zone Depth

m

SSL or Equation S25 in Appendix C, Table A

2 m or Calculated Value

d_a

Aquifer Thickness

m

Field Measurement

Site-Specific

d_s

Depth of Source

(Vertical thickness of contamination)

m

Field Measurement or Estimation

Site-Specific

Symbol

Parameter

Units

Source

Parameter Value(s)

D_A

Apparent Diffusivity

cm²/s

Equation S10 in Appendix C, Table A

Calculated Value

D_i

Diffusivity in Air

cm²/s

Appendix C, Table E

Chemical-Specific

D_w

Diffusivity in Water

cm²/s

Appendix C, Table E

Chemical-Specific

DF

Dilution Factor

unitless

Equation S22 in Appendix C, Table A

20 or Calculated Value

ED

Exposure Duration for Ingestion of Carcinogens

yr

Industrial/Commercial = 25

Construction Worker = 1

ED

Exposure Duration for Inhalation of Carcinogens

yr

Residential = 30

Industrial/Commercial = 25

Construction Worker = 1

ED

Exposure Duration for Ingestion of Noncarcinogens

yr

Residential = 6

Industrial/Commercial = 25

Construction Worker = 1

ED

Exposure Duration for Inhalation of Noncarcinogens

yr

Residential = 30

Industrial/Commercial = 25

Construction Worker = 1

ED

Exposure Duration for the Direct Ingestion of Groundwater

yr

Residential = 30

Industrial/Commercial = 25

Construction Worker = 1

ED_M-L

Exposure Duration for Migration to Groundwater Mass-Limit Equation S28

yr

SSL

70

EF

Exposure Frequency

d/yr

Residential = 350

Industrial/Commercial = 250

Construction Worker = 30

F(x)

Function dependent on U_m/U_t

unitless

SSL

0.194

f_oc

Organic Carbon Content of Soil

g/g

SSL or Field Measurement (See Appendix C, Table F)

Surface Soil = 0.006

Subsurface soil = 0.002, or Site-Specific

GW_obj

Groundwater Remediation Remediation Objective

mg/L

Appendix B, Table E, 35 IAC 620.Subpart F, or Equation S23 in Appendix C, Table A

Chemical-Specific or Calculated

H'

Henry's Law Constant

unitless

Appendix C, Table E

Chemical-Specific

i

Hydraulic Gradient

m/m

Field Measurement (See Appendix C, Table F)

Site-Specific

I

Infiltration Rate

m/yr

SSL

0.3

I_M-L

Infiltration Rate for Migration to Groundwater Mass-Limit Equation S28

m/yr

SSL

0.18

IF_soil-adj (residential)

Age Adjusted Soil Ingestion Factor for Carcinogens

(mg-yr)/ (kg-d)

SSL

114

IR_soil

Soil Ingestion Rate

mg/d

Residential = 200

Industrial/Commercial = 50

Construction Worker = 480

IR_W

Daily Water Ingestion Rate

L/d

Residential = 2

Industrial/Commercial = 1

K

Aquifer Hydraulic Conductivity

m/yr

Field Measurement (See Appendix C, Table F)

Site-Specific

K_d (Non-ionizing organics)

Soil-Water Partition Coefficient

cm³/g or L/kg

Equation S19 in Appendix C, Table A

Calculated Value

K_d (Ionizing organics)

Soil-Water Partition Coefficient

cm³/g or L/kg

Equation S19 in Appendix C, Table A

Chemical and pH-Specific (see Appendix C, Table I)

K_d (In-organics)

Soil-Water Partition Coefficient

cm³/g or L/kg

Appendix C, Table J

Chemical and pH-Specific

K_oc

Organic Carbon Partition Coefficient

cm³/g or L/kg

Appendix C, Table E or Appendix C, Table I

Chemical-Specific

K_s

Saturated Hydraulic Conductivity

m/yr

Appendix C, Table K

Appendix C, Illustration C

Site-Specific

L

Source Length Parallel to Groundwater Flow

m

Field Measurement

Site-Specific

PEF

Particulate Emission Factor

m³/kg

SSL or Equation S15 in Appendix C, Table A

Residential = 1.32 • 10⁹ or Site-Specific

Industrial/Commercial = 1.24 • 10⁹ or Site-Specific

PEF′

Particulate Emission Factor adjusted for Agitation (construction worker)

m³/kg

Equation S16 in Appendix C, Table A using PEF (industrial/commercial)

1.24 • 10⁸ or Site-Specific

Q/C (used in VF equations)

Inverse of the mean concentration at the center of a square source

(g/m²-s)/ (kg/m³)

Appendix C, Table H

Residential = 68.81

Industrial/Commercial = 85.81

Construction Worker = 85.81

Q/C (used in PEF equations)

Inverse of the mean concentration at the center of a square source

(g/m²-s)/ (kg/m³)

SSL or Appendix C, Table H

Residential = 90.80

Industrial/Commercial = 85.81

Construction Worker = 85.81

RfC

Inhalation Reference Concentration

mg/m³

Illinois EPA:  http://www.epa.state.il.us/land/taco/toxicity-values.xls

Toxicological-Specific (Note: for Construction Workers use subchronic reference concentrations)

RfD_o

Oral Reference Dose

mg/(kg-d)

Illinois EPA:  http://www.epa.state.il.us/land/taco/toxicity-values.xls

Toxicological-Specific (Note: for Construction Workers use subchronic reference doses)

RO_soil

Soil remediation objective

mg/kg

Equation S30 in Appendix C, Table A

Calculated value

RO_{soil gas}

Soil gas remediation objective

mg/m³

Equation S30 in Appendix C, Table A

Calculated value

S

Solubility in Water

mg/L

Appendix C, Table E

Chemical-Specific

SF_o

Oral Slope Factor

(mg/kg-d)^-1

Illinois EPA:  http://www.epa.state.il.us/land/taco/toxicity-values.xls

Toxicological-Specific

T

Exposure Interval

s

Residential = 9.5 • 10⁸

Industrial/Commercial = 7.9 • 10⁸

Construction Worker = 3.6 • 10⁶

T_M-L

Exposure Interval for Mass-Limit Volatilization Factor Equation S26

yr

SSL

30

THQ

Target Hazard Quotient

unitless

SSL

1

TR

Target Cancer Risk

unitless

Residential = 10^-6 at the point of human exposure

Industrial/Commercial = 10^-6 at the point of human exposure

Construction Worker = 10^-6 at the point of human exposure

U_m

Mean Annual Windspeed

m/s

SSL

4.69

URF

Inhalation Unit Risk Factor

(μg/m³)^-1

Illinois EPA:  http://www.epa.state.il.us/land/taco/toxicity-values.xls

Toxicological-Specific

U_t

Equivalent Threshold Value of Windspeed at 7 m

m/s

SSL

11.32

V

Fraction of Vegetative Cover

unitless

SSL or Field Measurement

0.5 of Site-Specific

VF

Volatilization Factor

m³/kg

Equation S8 in Appendix C, Table A

Calculated Value

VF′

Volatilization Factor adjusted for Agitation

m³/kg

Equation S9 in Appendix C, Table A

Calculated Value

VF_M-L

Mass-Limit Volatilization Factor

m³/kg

Equation S26 in Appendix C, Table A

Calculated Value

VF′_M-L

Mass-Limit Volatilization Factor adjusted for Agitation

m³/kg

Equation S27 in Appendix C, Table A

Calculated Value

η

Total Soil Porosity

L_pore/L_soil

SSL or Equation S24 in Appendix C, Table A

0.43, or

Gravel = 0.25

Sand = 0.32

Silt = 0.40

Clay = 0.36, or

Calculated Value

θ_a

Air-Filled Soil Porosity

L_air/L_soil

SSL or Equation S21 in Appendix C, Table A

Surface Soil (top 1 meter) = 0.28 Subsurface Soil (below 1 meter) = 0.13, or

Gravel = 0.05

Sand = 0.14

Silt = 0.24

Clay = 0.19, or

Calculated Value

θ_w

Water-Filled Soil Porosity

L_water/L_soil

SSL or Equation S20 in Appendix C, Table A

Surface Soil (top 1 meter) = 0.15

Subsurface Soil (below 1 meter) = 0.30, or

Gravel = 0.20

Sand = 0.18

Silt = 0.16

Clay = 0.17, or

Calculated Value

ρ_b

Dry Soil Bulk Density

kg/L or g/cm³

SSL or Field Measurement (See Appendix C, Table F)

1.5, or

Gravel = 2.0

Sand = 1.8

Silt = 1.6

Clay = 1.7, or

Site-Specific

ρ_s

Soil Particle Density

g/cm³

SSL or Field Measurement (See Appendix C, Table F)

2.65, or

Site-Specific

ρ_w

Water Density

g/cm³

SSL

1

1/(2b+3)

Exponential in Equation S20

unitless

Appendix C, Table K

Appendix C, Illustration C

Site-Specific