This document identifies and evaluates several key technical challenges for groundwater remediation at highly complex sites. As part of the mitigation measures for project risks associated with those technical challenges, the document also describes several long-term management designations and approaches used at complex sites to maintain protectiveness of human health and the environment over long time frames. These long-term management designations and approaches are typically one part of an overall site-specific remedial strategy that complies with existing regulations. Examples include the use of technical impracticability waivers, greater risk waivers, state designations for
groundwater management zones, and site management using phased approach. The use of these
designations at other highly complex sites is demonstrated through case studies.