SSL Soil Equations

Section 742 Section 742.710  SSL Soil Equations a)         This Section sets forth the equations and parameters used to develop Tier 2 soil remediation objectives for the three exposure routes using the SSL approach. b)         Soil Ingestion Exposure Route 1)         Equations S1 through S3 form the basis for calculating Tier 2 remediation objectives for the soil ingestion exposure route using the SSL approach.  Equation S1 is used to calculate soil remediation objectives for noncarcinogenic contaminants.  Equations S2 and S3 are used to calculate soil remediation objectives for carcinogenic contaminants for residential populations and industrial/commercial and construction worker populations, respectively. 2)         For Equations S1 through S3, the SSL default values cannot be modified with site-specific information. c)         Outdoor Inhalation Exposure Route 1)         Equations S4 through S16, S26 and S27 are used to calculate Tier 2 soil remediation objectives for the outdoor inhalation exposure route using the SSL approach.  To address this exposure route, organic contaminants and mercury must be evaluated separately from fugitive dust using their own equations set forth in subsections (c)(2) and (c)(3), respectively. 2)         Organic Contaminants A)        Equations S4 through S10 are used to calculate Tier 2 soil remediation objectives for organic contaminants and mercury based on the outdoor inhalation exposure route. Equation S4 is used to calculate soil remediation objectives for noncarcinogenic organic contaminants in soil for residential and industrial/commercial populations.  Equation S5 is used to calculate soil remediation objectives for noncarcinogenic organic contaminants and mercury in soil for construction worker populations.  Equation S6 is used to calculate soil remediation objectives for carcinogenic organic contaminants in soil for residential and industrial/commercial populations.  Equation S7 is used to calculate soil remediation objectives for carcinogenic organic contaminants in soil for construction worker populations.  Equations S8 through S10, S27 and S28 are used for calculating numerical values for some of the parameters in Equations S4 through S7. B)        For Equation S4, a numerical value for the Volatilization Factor (VF) can be calculated in accordance with subsection (c)(2)(F).  The remaining parameters in Equation S4 have either SSL default values listed in Appendix C, Table B or toxicological-specific information (i.e., RfC), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. C)        For Equation S5, a numerical value for the Volatilization Factor adjusted for Agitation (VF') can be calculated in accordance with subsection (c)(2)(G).  The remaining parameters in Equation S5 have either SSL default values listed in Appendix C, Table B or toxicological-specific information (i.e., RfC), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. D)        For Equation S6, a numerical value for VF can be calculated in accordance with subsection (c)(2)(F).  The remaining parameters in Equation S6 have either default values listed in Appendix C, Table B or toxicological-specific information (i.e., URF), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. E)        For Equation S7, a numerical value for VF' can be calculated in accordance with subsection (c)(2)(G).  The remaining parameters in Equation S7 have either default values listed in Appendix C, Table B or toxicological-specific information (i.e., URF), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. F)         The VF can be calculated for residential and industrial/commercial populations using one of the following equations based on the information known about the contaminant source and receptor population: i)          Equation S8, in conjunction with Equation S10, is used to calculate VF assuming an infinite source of contamination; or ii)         If the area and depth of the contaminant source are known or can be estimated reliably, mass limit considerations may be used to calculate VF using Equation S26. G)        The VF' can be calculated for the construction worker populations using one of the following equations based on the information known about the contaminant source: i)          Equation S9 is used to calculate VF' assuming an infinite source of contamination; or ii)         If the area and depth of the contaminant source are known or can be estimated reliably, mass limit considerations may be used to calculate VF' using Equation S27. 3)         Fugitive Dust A)        Equations S11 through S16 are used to calculate Tier 2 soil remediation objectives using the SSL fugitive dust model for the outdoor inhalation exposure route. Equation S11 is used to calculate soil remediation objectives for noncarcinogenic contaminants in fugitive dust for residential and industrial/commercial populations.  Equation S12 is used to calculate soil remediation objectives for noncarcinogenic contaminants in fugitive dust for construction worker populations.  Equation S13 is used to calculate soil remediation objectives for carcinogenic contaminants in fugitive dust for residential and industrial/commercial populations.  Equation S14 is used to calculate soil remediation objectives for carcinogenic contaminants in fugitive dust for construction worker populations.  Equations S15 and S16 are used for calculating numerical quantities for some of the parameters in Equations S11 through S14. B)        For Equation S11, a numerical value can be calculated for the Particulate Emission Factor (PEF) using Equation S15.  This equation relies on various input parameters from a variety of sources.  The remaining parameters in Equation S11 have either SSL default values listed in Appendix C, Table B or toxicological-specific information (i.e., RfC), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. C)        For Equation S12, a numerical value for the Particulate Emission Factor for Construction Worker (PEF') can be calculated using Equation S16.  The remaining parameters in Equation S12 have either SSL default values listed in Appendix C, Table B or toxicological-specific information (i.e., RfC), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. D)        For Equation S13, a numerical value for PEF can be calculated using Equation S15.  The remaining parameters in Equation S13 have either default values listed in Appendix C, Table B or toxicological-specific information (i.e., URF), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. E)        For Equation S14, a numerical value for PEF' can be calculated using Equation S16.  The remaining parameters in Equation S14 have either default values listed in Appendix C, Table B or toxicological-specific information (i.e., URF), which can be obtained by following the guidelines in OSWER Directive 9285.7-53, as incorporated by reference in Section 742.210 or requested from the program under which the remediation is being performed. d)         Soil Component of the Groundwater Ingestion Exposure Route The Tier 2 remediation objective for the soil component of the groundwater ingestion exposure route can be calculated using one of the following equations based on the information known about the contaminant source and receptor population: 1)         Equation S17 is used to calculate the remediation objective assuming an infinite source of contamination. A)        The numerical quantities for four parameters in Equation S17, the Target Soil Leachate Concentration (C w ), Soil-Water Partition Coefficient (K d ) for non-ionizing organics , Water-Filled Soil Porosity Thetaw  (θ w ) and Air-Filled Soil Porosity Thetaa (θ a ), are calculated using Equations S18, S19, S20 and S21, respectively.  Equations S22, S23, S24 and S25 are also needed to calculate numerical values for Equations S18 and S21.  The pH-dependent K d values for ionizing organics can be calculated using Equation S19 and the pH-dependent K oc values in Appendix C, Table I. B)        The remaining parameters in Equation S17 are Henry's Law Constant (H'), a chemical specific value listed in Appendix C, Table E and Dry Soil Bulk Density (ρ b ), a site-specific based value listed in Appendix C, Table B. C)        The default value for GW obj is the Tier 1 groundwater objective.  For chemicals for which there is no Tier 1 groundwater remediation objective, the value for GW obj shall be the concentration determined according to the procedures specified in 35 Ill. Adm. Code 620, Subpart F.  As an alternative to using Tier 1 groundwater remediation objectives or concentrations determined according to the procedures specified in 35 Ill. Adm. Code 620, Subpart F, GW obj may be developed using Equations R25 and R26, if approved institutional controls are in place as required in Subpart J. 2)         If the area and depth of the contaminant source are known or can be estimated reliably, mass limit considerations may be used to calculate the remediation objective for this exposure route using Equation S28.  The parameters in Equation S28 have default values listed in Appendix C, Table B.