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Monitored natural attenuation is an acceptable form of remediation for groundwater and soil.

Accelerated Site Closure Strategies

Remediation strategies for site closure have clearly undergone a series of significant transformations. Once the exclusive domain of energy intensive, mechanically driven methods, these core engineering processes have been actively replaced by or integrated with passive in-situ protocols.

Recently, yet another paradigm shift emerged as legitimate questions about site closure endpoints arose because of recalcitrant and asymptotic conditions that confounded clean-up goals. In response to this need, a number of validated advanced diagnostic methods have been employed to generate new lines of evidence ─ in support of expedited closure. This approach usually operates within the framework of monitored natural attenuation (MNA). When coupled with guaranteed fixed-price strategies, these outcomes are of particular relevance for better site management.

The objective of this blog post is to provide insights on a proven, comprehensive program that has generated real outcomes for cost management and expedited site closure.

A comprehensive program for cost management and expedited closure should include the use of a variety of environmental molecular diagnostics in concert with, where applicable, novel geotechnical techniques. The recent emergence of molecular biological tools (MBTs) and compound-specific stable isotope analysis (CSIA) as well as two subsets of geotechnical science ("enviro-tomography” and "flux assessment") are all rich in content and powerful in scope of application. One thrust of the use of these techniques is to set forth proper arguments that can justify MNA as the remedy of choice along the way to permanent site closure. Even absent this endpoint objective, the use of advanced diagnostics has value insofar as better site assessment and management protocols can emerge. Examples include:

  • the use of simple qPCR-based MBTs to clarify when a treatment train transition from chemical oxidation to bioremediation is most sensible,
  • the use of microarrays to determine when the total microbial community as represented in a metagenomic context is ready for more electron donor substrate, and
  • proving any of the variety of chemical and/or biological oxidation or reduction treatment options are actually degrading the compounds of concern via CSIA.

The impact on site exit strategies, essentially the most important ultimate objective, is just beginning to manifest. This blog will detail specific achievement via a series of guest practitioners that can discuss their specific accomplishments. Overall, the point is that:

  • a variety of advanced diagnostic strategies can be integrated into a framework that can be used in concert with any of the ubiquitous and varied remediation strategies and products being marketed and
  • there are a variety of vendors and academic services that [which] can be employed to facilitate said integration.

The ultimate lesson learned is that the industry now has a new opportunity for resolving many contaminated site issues. The ultimate result will be to reduce a burdensome national inventory of legacy and emergent problems with a heretofore unavailable greater scientific insight.

A metric to the growth of this “movement” is the considerable funding support and conference exposure offered by the Strategic Environmental Research and Development Program, which is a consortium of DOD, DOE, and EPA and other conference venues hosted by Battelle and AEHS. In terms of important long-term efforts, it must be noted that the Interstate Technology and Regulatory Council recently formed a Team for Environmental Molecular Diagnostics (EMD) that proposes to review and express sound guidance for the evolving use of molecular biological and stable isotope techniques (see: www.itrcweb.org/teampublic_EMD.asp).

About the image: When chlorinated solvents are spilled or leak into soil or groundwater, natural processes occur to destroy or alter the chemicals. This natural attenuation is recognized by EPA as a viable method of remediation.

Stephen Koenigsberg, Ph.D., is vice president of The Adventus Group.

Posted by Stephen S. Koenigsberg, Ph.D. on Jan 27, 2011 at 12:43 PM


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