IDEM R2 Walkthrough - Indiana Risk-based Closure Guide (WASTE-0046-R2)
Practical walkthrough of IDEM's R2 closure guide for all Indiana cleanup programs. Covers published levels, characterization, risk evaluation, and closure.
Overview
The Risk-based Closure Guide, formally IDEM Nonrule Policy Document WASTE-0046-R2, is the central technical guidance document for environmental site closures in Indiana. Published July 8, 2022 by IDEM’s Office of Land Quality, it replaced the previous Remediation Closure Guide and is commonly referred to as “the R2.”
The R2 applies uniformly across all five IDEM cleanup programs: the Voluntary Remediation Program (VRP), the State Cleanup Program (SCP), petroleum remediation (LUST), RCRA Subtitle C programs (including corrective action), and the Indiana Brownfields Program (IBP).
If you do remediation work in Indiana, you will use this document. Every investigation work plan, risk evaluation, and closure request must follow the R2 framework. Unlike Ohio’s VAP (which has its own self-contained standards in OAC 3745-300), Indiana’s approach funnels all cleanup programs through a single technical guidance document.
The statutory basis for the R2 is IC 13-12-3-2 (remediation and closure goals) and IC 13-25-5-8.5 (voluntary remediation work plan objectives). The R2 is a nonrule policy document - it is guidance, not a rule - but IDEM applies it consistently. Responsible parties may propose alternate approaches, and IDEM will evaluate them on their merits.
Structure of the R2
The R2 is organized into three major sections containing nine tasks total. If no remedy is needed, only seven tasks apply (Tasks 8 and 9 are skipped).
Section 2: Characterization (Tasks 1-3)
The goal of characterization is to determine the source, nature, and extents of release-related chemicals. IC 13-25-5-8.5(c) requires adequate characterization as a prerequisite to determining whether action is necessary to protect human health and the environment.
The R2 emphasizes that characterization must support a conceptual site model (CSM) - a comprehensive understanding of the release, its setting, and the relationships between sources, affected media, and potential receptors. The CSM is not a standalone task or a single document. It is an iterative, living representation of the site that develops throughout the project and is never considered complete until final closure.
Task 1: Identify release source(s). Determine the type of activity or facility associated with the release and, to the extent possible, the physical location of the source point or source area. The R2 Table 2-A lists chemicals of concern for various product and waste types by media. For release types not listed, contact the IDEM Closure Coordinator.
Task 2: Identify and quantify release-related chemicals. Develop appropriate data quality objectives (DQOs) and determine the chemicals and breakdown products likely associated with the release and their concentrations in affected media. This task covers sample planning, sampling methods for soil, groundwater, and vapor, sample handling and analysis, data reporting, and data evaluation. This is the core analytical investigation phase.
Task 3: Determine the extents of release-related chemicals. Determine the present horizontal and vertical extents of release-related chemicals in all affected media, measured against unconditional remediation objectives. Estimate likely future extents against the same objectives. This is the delineation phase - define the boundaries of contamination in soil, groundwater, and vapor until concentrations are below the applicable Published Levels or you have established the plume limits.
Section 3: Risk Evaluation (Tasks 4-7)
Once characterization is complete, the R2 requires a risk evaluation to determine whether the release poses unacceptable risk and, if so, what the remediation targets should be.
Task 4: Specify decision unit(s) and their use(s). Specify the extents and likely future uses of locations where remedy decisions are necessary. A decision unit is the area for which a remedy decision will be made - it defines both the spatial boundaries and the land use assumptions (residential, commercial/industrial) that drive the risk evaluation.
Task 5: Determine representative concentrations. Develop estimates of release-related chemical concentrations within each decision unit. This is a statistical exercise - it requires determining what concentrations best represent exposure within the decision unit, not just reporting maximum detections.
Task 6: Specify remediation objectives. Specify the risk-based concentrations or risk levels that the site must meet for closure. Remediation objectives can be based on several approaches: naturally occurring background concentrations, IDEM’s Published Levels (the default screening values), site-specific levels derived from project-specific risk assessments, or risk levels as allowed under IC 13-25-5-8.5(c).
Indiana uses a target cancer risk of 1E-05 (one in 100,000) for deriving Published Levels, which is 10 times less conservative than EPA’s default 1E-06. This means Indiana’s screening levels are generally higher (less stringent) than EPA RSLs for carcinogens. For non-carcinogens, Indiana uses a target hazard quotient of 1.0, consistent with EPA.
Task 7: Determine whether a remedy is necessary. Determine whether representative concentrations in decision units exceed unconditional remediation objectives and evaluate applicable lines of evidence when deciding whether a remedy is necessary. This task has detailed subsections covering remedy necessity for soil exposure, leaching potential, groundwater exposure, vapor exposure, and other media. Risk characterization integrates findings across all pathways.
If representative concentrations do not exceed unconditional remediation objectives in any decision unit, the site may proceed directly to closure without Tasks 8 and 9.
Section 4: Remedies (Tasks 8-9)
If the risk evaluation confirms a remedy is necessary, the R2 requires remedy selection and implementation.
Task 8: Select an adequate remedy. Choose a remedy that is likely to adequately control risk, considering the present and likely future extents of release-related chemicals, their concentrations, overlap with potential receptors, land-use-specific remediation objectives, and proposed controls. Remedy categories include active remediation (excavation, treatment systems, monitored natural attenuation), engineered exposure controls (caps, barriers, subslab depressurization), and institutional controls (land use restrictions via ERCs or EROs). Long-term stewardship and financial assurance requirements are also addressed.
Task 9: Implement remedy and confirm adequacy. Implement the proposed remedy and demonstrate, using sampling data and other evidence, that it adequately controls risk. The demonstration must show that the remedy is likely to be effective for as long as release-related chemicals remain above residential remediation objectives, that restricted activities are being complied with, and that future obligations related to ongoing operation and maintenance are adequately specified, documented, and financially supported.
Types of Closure
Unconditional Closure
Unconditional closure means no ongoing remedy is required and the property is suitable for unrestricted use. This is achieved when release-related chemical concentrations are below unconditional remediation objectives - typically IDEM’s residential Published Levels or naturally occurring background levels. IDEM does not anticipate requiring additional action at a property that closes unconditionally.
Conditional Closure
Conditional closure means an ongoing remedy is necessary to reduce exposure risk to an acceptable level. This could include physical barriers, active remediation systems (such as subslab depressurization for vapor intrusion), or land use controls (such as residential use prohibitions or groundwater extraction restrictions). Releases may need more than one remedy to adequately control risk.
Conditional closure requires an Environmental Restrictive Covenant (ERC) recorded on the property deed describing the identity, quantity, and location of remaining contamination and the restrictions that apply.
The R2 notes that responsible parties should weigh the short-term advantages of conditional closure against the potential costs of maintaining remedies for as long as necessary. For persistent chemicals, controls may need to remain in place in perpetuity. Removal or treatment of release-related chemicals will usually reduce the number, scale, and duration of ongoing controls.
Financial assurance may be required for conditional closures (Appendix G).
How the R2 Applies Across Programs
| Program | R2 applies? | Additional program-specific guidance |
|---|---|---|
| Voluntary Remediation Program (VRP) | Yes - full R2 | VRP forms and VRP-specific procedures (IC 13-25-5) |
| State Cleanup Program (SCP) | Yes - full R2 | NCP-modeled process; IDEM may direct investigation scope |
| Petroleum Remediation (LUST) | Yes - R2 plus WASTE-0082 supplement | Petroleum Remediation Program Guide supplements the R2 for petroleum-specific issues |
| RCRA Subtitle C (Corrective Action) | Yes - R2 plus WASTE-0015-R1 | RCRA Closure and Corrective Action Guide applies to RCRA-regulated units |
| Indiana Brownfields Program (IBP) | Yes - full R2 | Administered by Indiana Finance Authority (IFA), not IDEM |
The R2 is the base document for all five programs. Program-specific supplements add requirements unique to that program, but the core characterization-risk-remedy framework is the same.
Key Differences from Ohio
| Indiana (R2) | Ohio (VAP/OAC 3745-300) | |
|---|---|---|
| Guidance document | Single R2 applies across all programs | VAP has its own standards; BUSTR and DERR have separate guidance |
| Cancer risk level | 1E-05 | 1E-06 |
| Screening values | Published Levels (from IDEM tables) | Generic standards (from CIDARS) |
| Soil migration to groundwater | Evaluated site-specifically through R2 | LBSVs (leach-based soil values) published as default screening levels |
| Closure mechanism | Closure letter from IDEM; ERC for conditional | NFA letter; Covenant Not to Sue for restricted |
| Soil gas | Published Levels for soil gas (subslab, deep exterior, shallow exterior) | No published soil gas standards; uses EPA VISL |
| Process structure | 9 tasks across 3 sections (7 if no remedy needed) | Phase I, Phase II, standards comparison, NFA application |
The most significant practical difference is the cancer risk level. Indiana’s 1E-05 means that for carcinogens, Indiana’s Published Levels are roughly 10 times higher than Ohio’s generic standards. Benzene, for example, has no residential or commercial soil Published Level in Indiana - only an excavation value of 2,000 mg/kg - while Ohio publishes residential and commercial soil standards through CIDARS.
Practical Tips
Start with the Published Level comparison. Before planning any investigation, check whether your chemicals of concern have Published Levels in the applicable media and land use. If your site is commercial/industrial and all detected concentrations are below commercial Published Levels, you may be able to move through risk evaluation quickly.
The CSM drives everything. IDEM reviewers evaluate work plans and closure documents against the conceptual site model. If your CSM has gaps - uncharacterized media, incomplete receptor identification, unexplained detections - expect comments. Build a strong CSM from the start and update it as new data comes in.
Soil gas matters in Indiana. Unlike Ohio, Indiana publishes soil gas screening levels for 154 chemicals across three sample types (subslab, deep exterior, shallow exterior) and three land uses. Vapor intrusion evaluation in Indiana starts with these Published Levels rather than requiring you to run the EPA VISL calculator.
Decision units are central to the R2. The concept of decision units in Task 4 drives how you evaluate risk. Define them carefully - they determine both the spatial scope of your analysis and the land use assumptions that select which Published Levels apply.
Financial assurance for conditional closures. If your remedy involves long-term monitoring, engineering controls, or institutional controls, IDEM may require financial assurance. Budget for this early. Appendix G describes how IDEM evaluates financial assurance proposals.
The R2 is guidance, not a rule. Deviations are possible with strong technical justification. If you have a site-specific reason to deviate from the default approach, document your rationale clearly and discuss it with the IDEM project manager before submitting your work plan.
Key Forms and Documents
Risk-based Closure Guide (WASTE-0046-R2): Available on the IDEM Effective Nonrule Policies page. Petroleum Remediation Program Guide (WASTE-0082): Supplement to the R2 for petroleum sites. RCRA Closure and Corrective Action Guide (WASTE-0015-R1): Supplement for RCRA sites. VRP Application Form: Available on the IDEM Agency Forms page. Environmental Restrictive Covenant Template: Available on the IDEM VRP Resources page.
Source
IDEM Nonrule Policy Document WASTE-0046-R2: Risk-based Closure Guide, July 8, 2022. IC 13-12-3-2: Remediation and closure goals, objectives, and standards. IC 13-25-5-8.5: Voluntary remediation work plan objectives. IDEM Technical Guidance for Cleanups page (in.gov/idem/cleanups/resources/technical-guidance-for-cleanups/).