The Triad builds on experiences gained from prior efforts to improve the CERCLA and RCRA corrective action processes begun in the 1980s. The Triad is a natural technical practice progression in response to advances in science and technology. This progression has been in concert with policy development driven by economics and a maturing regulatory environment. The Triad embraces techniques and concepts used by the Observational Approach and Expedited Site Characterization to manage environmental decision-making in the presence of uncertainty. The Triad reflects EPA’s efforts to organize past successful modifications to the standard CERCLA and RCRA corrective action process into a coherent, replicable, technically defensible approach for managing the uncertainty associated with hazardous waste site decision-making.

In the past decade there have been significant technological and methodological advancements in analytical methods and measurement systems, as well as in supporting technologies such as Global Positioning Systems and direct-push sampling techniques. Some of these advancements have found their way into SW-846 guidance and day-to-day field practices and are here to stay. Their availability is what makes the approach advocated by the Triad possible. There are already ample case studies that demonstrate the potential benefits of weaving real-time measurement systems into the characterization and remediation process. The expectation is that as practitioners, regulators, technology providers, and project managers become comfortable with a Triad approach, the use of Triad components (e.g., systematic planning, dynamic work strategies, and real-time measurement systems) will become standard practice.