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HWIR Frequent Questions
1. What is EPA finalizing under the 2001 Hazardous Waste Identification Rule (HWIR)?EPA is finalizing, with revisions, the retention of the hazardous waste mixture and derived-from rules. The mixture and derived-from rules are a key part of the Resource Conservation and Recovery Act (RCRA) rules that define when wastes are regulated as hazardous wastes.
- Under the mixture rule, a listed hazardous waste remains regulated
as a hazardous waste when it is mixed with a non-hazardous waste.
- Under the derived-from rule, waste generated from the treatment, storage, or disposal of a listed hazardous waste also remains regulated as a hazardous waste.
In addition, EPA is finalizing two new exemptions that narrow the scope of these rules, tailoring them to match the risks posed by particular wastes:
- an exemption for wastes listed solely for ignitability, corrosivity
and/or reactivity characteristics. Currently, mixtures of such wastes
that are decharacterized are eligible for exemption. The revised rule
extends this exemption to include all such wastes. These wastes are
still subject to any applicable land disposal restriction requirements.
- a conditional exemption for mixed wastes (that is, wastes that are both hazardous and radioactive) when they meet certain conditions and eligibility criteria.
2. How does the final rule compare to the 1999 HWIR proposal?
We are largely finalizing the revisions to the mixture and derived-from rules as they were proposed. In response to public comments, we have clarified that land disposal restrictions (LDRs) only affect the exempted waste where they are otherwise applicable under current regulation. (In other words, if a waste is not subject to LDRs under the current regulations, it would not be subject under the revised regulations). We have also moved the regulatory language for the conditional exemption for mixed waste to its own subsection (40 CFR 261.3(h)) in order to make it more clear.
3. What are EPA's plans for future work related to HWIR?
EPA plans to continue development of a concentration-based HWIR exemption based on results from the Multi-media, Multi-pathway and Multi-receptor risk assessment (3MRA) Model. We are currently reviewing the public comments and will decide if further revisions to the HWIR risk assessment (3MRA) model are necessary. We also are continuing independent testing and plan to submit the model to EPA's Science Advisory Board (SAB) for review. Before using the revised risk assessment to support a final rulemaking on the HWIR exemption, we will publish a proposal to allow public comment on a unified package.
In another effort to better calibrate risk and regulatory standards, EPA is also developing two targeted exemptions from the hazardous waste mixture and derived-from rules: one for certain solvents destined for wastewater treatment and discharge under the Clean Water Act, and another for slagged combustion residues from hazardous waste combustors. Other targeted exemptions are being assessed for later development. We also plan to continue on-going efforts to streamline the existing delisting process.