This document provides guidance to RCRA facility permit applicants and writers concerning the establishment of site-specific Alternate Concentration Limits (ACLs). To obtain an ACL, a permit applicant must demonstrate that the hazardous constituents detected in the groundwater will not pose a substantial present or potential hazard to human health or the environment at the ACL levels.

• Alternate Concentration Limit Guidance (Part 1): ACL Policy and Information Requirements (PDF)(128 pp, 4 MB, July 1987)
  A guidance document to help regional and state personnel to exercise discretion in their application evaluations for ACLs submitted to ensure that they meet regulatory standards.