CHAPTER I: DEPARTMENT OF AGRICULTURE
SUBCHAPTER i: PESTICIDE CONTROL
PART 259 AGRICHEMICAL FACILITY RESPONSE ACTION PROGRAM
SECTION 259.350 EQUATIONS FOR CALCULATING SITE-SPECIFIC SOIL CLEANUP OBJECTIVES
Section 259.350 Equations for Calculating Site-Specific Soil Cleanup Objectives
a) Site-specific soil cleanup objectives for pesticides are determined by the following equation:
Where:
|
SCO |
= |
soil cleanup objective (mg/kg) |
|
Cw |
= |
target soil leachate concentration (mg/L) |
|
Koc |
= |
organic carbon partition coefficient (L/kg) |
|
foc |
= |
organic carbon content of soil (kg/kg) |
|
Θw |
= |
water-filled soil porosity (Lwater/Lsoil) |
|
Θa |
= |
air-filled soil porosity (Lair/Lsoil) |
|
H' |
= |
Henry's law constant (dimensionless) |
|
Ρb |
= |
dry soil bulk density (kg/L) |
References:
"Soil Screening Guidance: User's Guide", p. 29, eq. 10.
"Soil Screening Guidance: Technical Background Document", p. 37, eq. 24.
1) The target soil leachate concentration can be determined by the following equation:
Where:
|
Cw |
= |
target soil leachate concentration (mg/L) |
|
DF |
= |
groundwater dilution factor (dimensionless) |
|
GWobj |
= |
groundwater cleanup objective (mg/L) |
2) The dilution factor can be determined by the following equation:
Where:
|
DF |
= |
groundwater dilution factor (unitless) |
|
K |
= |
aquifer hydraulic conductivity (m/yr) |
|
i |
= |
hydraulic gradient (m/m) |
|
d |
= |
mixing zone depth (m) |
|
R |
= |
groundwater recharge rate (m/yr) |
|
L |
= |
length of contaminated soil parallel to groundwater flow (m) |
|
W |
= |
width of contaminated soil perpendicular to groundwater flow (m) |
b) Site-specific soil cleanup objectives for nitrate as nitrogen can be determined by the following equation:
Where:
|
L |
= |
Liter |
|
Cw |
= |
Target soil leachate concentration (mg/L) |
c) Site-specific soil cleanup objectives for ammonium can be determined by the following empirical equation:
Where:
|
CEC |
= |
cation exchange capacity (meq/100g) |
Reference:
Potential Soil Cleanup Objectives for Nitrogen-Containing Fertilizers at Agrichemical Facilities, Soil and Sediment Contamination.
d) The default values for the equations in subsections (a) and (b) of this Section are:
|
Parameter |
|
Description |
|
Default Value |
|
DF |
|
Groundwater dilution factor |
|
30 (dimensionless) |
|
foc |
|
Organic carbon content of soil |
|
0.008 kg/kg (0.8%) surface or 0.002 kg/kg (0.2%) subsurface |
|
Θa |
|
Air-filled soil porosity |
|
0.2 (20%) Lair/Lsoil |
|
Θw |
|
Water-filled soil porosity |
|
0.2 (20%) Lwater/Lsoil |
|
Ρb |
|
Dry soil bulk density |
|
1.6 kg/L |
|
H' |
|
Henry's law constant |
|
see Appendix E |
|
Koc |
|
Organic carbon partition coefficient |
|
see Appendix E |
|
GWobj |
|
Groundwater cleanup objective |
|
see Appendix D |
|
|
|
|
|
|
|
CEC |
|
Cation exchange capacity |
|
see Appendix F |
(Source: Amended at 32 Ill. Reg. 1308, effective January 21, 2008)