Ill. Admin. Code tit. 8, § 259.350 - Equations for Calculating Site-Specific Soil Cleanup Objectives

a) Site-specific soil cleanup objectives for pesticides are determined by the following equation:

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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)
[THETA]w	=	water-filled soil porosity (Lwater/Lsoil)
[THETA]a	=	air-filled soil porosity (Lair/Lsoil)
H'	=	Henry's law constant (dimensionless)
[RHO]b	=	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:

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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:

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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:

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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:

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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
[THETA]a	Air-filled soil porosity	0.2 (20%) Lair/Lsoil
[THETA]w	Water-filled soil porosity	0.2 (20%) Lwater/Lsoil
[RHO]b	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

Notes

Ill. Admin. Code tit. 8, § 259.350

Amended at 32 Ill. Reg. 1308, effective January 21, 2008