The objective of this project is to foster broader understanding and acceptance of the Enhanced Monitored Natural Recovery (EMNR) remedy through demonstration and validation of performance and cost-effectiveness at Department of Defense (DoD) contaminated sediment sites. The effort will focus on two key technical performance issues, specifically (1) How effective is the EMNR remedy? and (2) How well do available monitoring tools gauge the effectiveness of the EMNR remedy?
EMNR technology relies on a combination of enhanced natural recovery via placing a thin (6-12 in or 15-30 cm) layer of clean sediment over contaminated sediment and an effective characterization and monitoring program to project and verify recovery. The thin layer cap (TLC) is not intended to provide a complete seal over the contaminated sediment as in a conventional isolation capping operation. Instead, the TLC provides a surface layer of cleaner sediment, resulting in an immediate reduction in surface contaminant concentrations that facilitates the re-establishment of benthic organisms, minimizes short term disruption of the benthic community, and effectively accelerates the process of physical isolation continued over time by natural sediment deposition. Depending on the rates of natural sedimentation and erosion, bioturbation mixes TLC material with underlying contaminated sediments (encouraging natural recovery processes such as transformation), or natural sedimentation further physically isolates contaminated sediment and lower layers of TLC beyond the biologically active surface depths, resulting in disruption of exposure pathways to benthic organisms.
DoD faces increasing demands to address contaminated sediment sites, requiring improved understanding of potential remedial options and methods to assess their performance. Broader use of EMNR benefits DoD through reduced material costs compared to conventional isolation capping or dredging, reduced long-term monitoring costs compared to MNR, elimination of removal and disposal costs associated with dredging, and elimination or reduction of impacts to benthic communities compared to conventional isolation capping and dredging approaches. DoD sediment cleanup costs are estimated to exceed $1 billion using traditional capping and dredging; EMNR could save DoD hundreds of millions of dollars. (Anticipated Project Completion - 2013)