Illinois Code § 58.5

§ 58.5.

Risk-based remediation objectives. (a) Determination of remediation objectives. This Section establishes the procedures for determining risk-based remediation objectives. (b) Background area remediation objectives. (1) Except as provided in subdivisions (b)(2) or (b)(3) of this Section, remediation objectives established under this Section shall not require remediation of regulated substances to levels that are less than area background levels. (2) In the event that the concentration of a regulated substance of concern on the site exceeds a remediation objective adopted by the Board for residential land use, the property may not be converted to residential use unless such remediation objective or an alternate risk-based remediation objective for that regulated substance of concern is first achieved. (3) In the event that the Agency has determined in writing that the background level for a regulated substance poses an acute threat to human health or the environment at the site when considering the post-remedial action land use, the RA shall develop appropriate risk-based remediation objectives in accordance with this Section. (c) Regulations establishing remediation objectives and methodologies for deriving remediation objectives for individual or classes of regulated substances shall be adopted by the Board in accordance with this Section and Section 58.11. (1) The regulations shall provide for the adoption of a three-tiered process for an RA to establish remediation objectives protective of human health and the environment based on identified risks and specific site characteristics at and around the site. (2) The regulations shall provide procedures for using alternative tiers in developing remediation objectives for multiple regulated substances. (3) The regulations shall provide procedures for determining area background contaminant levels. (4) The methodologies adopted under this Section shall ensure that the following factors are taken into account in determining remediation objectives: (A) potential risks posed by carcinogens and noncarcinogens; and (B) the presence of multiple substances of concern and multiple exposure pathways. (d) In developing remediation objectives under subsection (c) of this Section, the methodology proposed and adopted shall establish tiers addressing manmade and natural pathways of exposure, including, but not limited to, human ingestion, human inhalation, and groundwater protection. For carcinogens, soil and groundwater remediation objectives shall be established at exposures that represent an excess upper-bound lifetime risk of between 1 in 10,000 and 1 in 1,000,000 as appropriate for the post-remedial action use, except that remediation objectives protecting residential use shall be based on exposures that represent an excess upper-bound lifetime risk of 1 in 1,000,000. No groundwater remediation objective adopted pursuant to this Section shall be more restrictive than the applicable Class I or Class III Groundwater Quality Standard adopted by the Board. At a minimum, the objectives shall include the following: (1) Tier I remediation objectives expressed as a table of numeric values for soil and groundwater. Such objectives may be of different values dependent on potential pathways at the site and different land uses, including residential and nonresidential uses. (2) Tier II remediation objectives shall include the formulae and equations used to derive the Tier II objectives and input variables for use in the formulae. The RA may alter the input variables when it is demonstrated that the specific circumstances at and around the site including land uses warrant such alternate variables. (3) Tier III remediation objectives shall include methodologies to allow for the development of site-specific risk-based remediation objectives for soil or groundwater, or both, for regulated substances. Such methodology shall allow for different remediation objectives for residential and various categories of non-residential land uses. The Board's future adoption of a methodology pursuant to this Section shall in no way preclude the use of a nationally recognized methodology to be used for the development of site-specific risk-based objectives for regulated substances under this Section. In determining Tier III remediation objectives under this subsection, all of the following factors shall be considered: (A) The use of specific site characteristic data. (B) The use of appropriate exposure factors for the current and currently planned future land use of the site and adjacent property and the effectiveness of engineering, institutional, or legal controls placed on the current or future use of the site. (C) The use of appropriate statistical methodologies to establish statistically valid remediation objectives. (D) The actual and potential impact of regulated substances to receptors. (4) For regulated substances that have a groundwater quality standard established pursuant to the Illinois Groundwater Protection Act and rules promulgated thereunder, site specific groundwater remediation objectives may be proposed under the methodology established in subdivision (d)(3) of this Section at values greater than the groundwater quality standards. (A) The RA proposing any site specific groundwater remediation objective at a value greater than the applicable groundwater quality standard shall demonstrate: (i) To the extent practical, the exceedance of the groundwater quality standard has been minimized and beneficial use appropriate to the groundwater that was impacted has been returned; and (ii) Any threat to human health or the environment has been minimized. (B) The rules proposed by the Agency and adopted by the Board under this Section shall include criteria required for the demonstration of the suitability of groundwater objectives proposed under subdivision (b) (4) (A) of this Section. (e) The rules proposed by the Agency and adopted by the Board under this Section shall include conditions for the establishment and duration of groundwater management zones by rule, as appropriate, at sites undergoing remedial action under this Title. (f) Until such time as the Board adopts remediation objectives under this Section, the remediation objectives adopted by the Board under Title XVI of this Act shall apply to all environmental assessments and soil or groundwater remedial action conducted under this Title. (Source: P.A. 103-605, eff. 7-1-24.)