THE JOYS AND PERILS OF ALTERNATE COMPLIANCE STRATEGIES -- MIXING ZONES, NATURAL REMEDIATION, LONG TERM MONITORING, AND THE LIKE

During the last decade, various alternate compliance strategies - groundwater mixing zones, natural attenuation, long-term monitoring schemes, etc. - have become increasingly important tools in achieving cost effective and technically defensible solutions for environmental contamination. These and similar alternate compliance plans have been described erroneously as the "do nothing" approach. In fact, a better description would be the "understand everything" approach, for the successful implementation of any alternate compliance strategy depends on a complete understanding of a host of technical, programmatic, regulatory, and site specific factors.

At the Department of Energy's Savannah River Site, alternate compliance strategies have been implemented successfully as stand-alone solutions (at sites where the contaminant source is exhausted, for example) and as elements of more complex remedial strategies (for example, in tandem with engineered measures or removal actions to control the contaminant source). In each of these cases, the prerequisite for implementing and maintaining an alternate compliance approach was a thorough understanding of the pertinent geology, hydrostratigraphy, biological and geochemical conditions, contaminant distribution and transport, proximity of potential human and ecological receptors, regulatory framework, and cost and schedule limitations.

Selecting and implementing the most appropriate alternate compliance strategy may require more up-front effort and site specific data than relying on more traditional remediation approaches. However, in many cases, the alternate compliance strategy achieves the same results as the traditional approach, costs less over the life of the project, and may pose less collateral damage to the environment. Hence, mixing zones, monitored natural attenuation, long-term monitoring schemes, and other alternate compliance ideas yet to be discovered will continue to be important elements in the cost effective remediation of the Savannah River Site.