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

   1. 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)

   

   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.

2. 2) The dilution factor can be determined by the following equation:

   1. 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)

   2. 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.

   3. 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

   

   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)

(Source: Amended at 32 Ill. Reg. 1308, effective January 21, 2008)