This regulatory impact analysis (RIA) estimates the costs, economic impacts, and benefits of the supplemental proposed rule applying Phase IV Land Disposal Restrictions (LDRs) to newly identified hazardous mineral processing wastes. This proposal modifies potential waste management requirements that were originally proposed on January 25, 1996 (61 FR 2338). EPA is proposing standards for mineral processing wastes no longer exempt from Subtitle C requirements under the Bevill exemption. Under the provisions of the proposal, previously exempt Bevill mineral processing wastes destined for disposal would need to be treated to meet RCRA Universal Treatment Standards (UTS) before management or disposal in a land-based unit. At the same time, however, operators could reclaim hazardous mineral processing residues and store them in non-land based units prior to reclamation without complying with full Subtitle C requirements, under certain specified conditions.