Welcome! This website is the repository for the products of a Savannah River National Laboratory led applied research and development effort that developed processes and tools to support the use of Monitored Natural Attenuation and Enhanced Attenuation at chlorinated solvent contaminated sites. The project used as its cornerstone the 1998 EPA Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Groundwater and the 1999 Office of Solid Waste and Emergency Response Directive Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites, Final. A team of nationallly respected scientists and engineers led this effort, several being key contributors to the EPA's 1998 technical protocol.

Recent Information - Natural Attenuation of Chlorinated Solvents: Recent Developments and Practical Tools - May 2008 (PDF 9Mbytes)

This project was initiated in 2003 based on technical needs identified by several of the large Department of Energy sites that were considering the use of MNA as part of the remedial actions for their large chlorinated solvent sites. A challenge being faced at these sites, besides the size of the chlorinated solvent plumes, was that these sites were situated in aerobic groundwater. The EPA documents while allowing the use of a multitude of attenuation mechanisms, provided guidance that was specific to anaerobic reductive dechlorination. Thus, additional guidance was needed. To support the needs of the sites, the Department of Energy's Office of Environmental Management funded this project to address the identified challenges and develop tools and guidance that site owners and responsible parties in the federal, public, and private sectors could incorporate into their remediation efforts.

Three key areas associated with attenuation based remedies were investigated. These are:
Mass Balance - process for evaluating both the stability and sustainability of a contaminant plume
Enhanced Attenuation - class of actions that are divided into those that decrease loading to the contaminant plume and those that increase attenuation rate and are designed with sustainability as a central objective.
Four phased approach to characterization and monitoring - an approach to characterization that supports collecting data that targets the most robust attenuation mechnisms and generates input to the mass balance and an approach to monitoring that results in use of indicator parameters in place of traditional well sampling for long-term monitoring.

An invaluable collaboration was formed with the Interstate Technology and Regulatory Council (ITRC) in 2003 with the formation of a new ITRC team, Enhanced Attenuation: Chlorinated Organics.