Most of the less complex sites, where contamination is limited to above the water table, have been cleaned up. The most difficult sites where groundwater has been impacted by chlorinated solvents or emerging contaminants represent the greatest challenge. While there is still a need to implement large remedial systems to extract and treat groundwater, remove contaminants, and prevent plume expansion to achieve containment, there has been a dramatic shift to in situ technologies and other natural attenuation processes. It must also be recognized that inconsistencies in the original conceptual site model may have led to mischaracterization of site and assumptions made during the planning stages that may have set unrealistic remedial end points based on current technology. A revitalized conceptual site model that is based on high resolution site characterization, Environmental Sequence Stratigraphy, and increased use of formal, numerical modeling techniques is a critical step toward a sustainable site exit strategy. Using adaptive management principles, we emphasize to stakeholders the cost/benefit tradeoffs of investment, timeframes, risk reduction, and long-term liability to develop a clear optimized remedial strategy for the site.
EA worked diligently and thoroughly to maintain the construction schedules, ensure that the remedial action system worked when the project came on line, and that EPA and the State of Texas met the scheduled commitment for Fiscal Year 2009. The treatment system at the remedial action is a major milestone in the Agency’s green remediation program and was recognized by senior management as a significant accomplishment.—Rena McClurg, EPA Project Officer.