Monitored natural attenuation forum: The case for abiotic MNA

The environmental fate and transport of chlorinated volatile organic compounds (VOCs) is controlled by the physical and chemical properties of the compound and the nature of the subsurface media through which the compound is migrating. Several processes (advection, dispersion, diffusion, biodegradation, and abiotic degradation, to name a few) result in a reduction in concentration and/or mass of contaminants in groundwater. Of these processes, biodegradation is often considered the dominant destructive attenuation mechanism for chlorinated VOCs. However, chlorinated VOCs can also degrade through abiotic processes and, in some cases, may be the primary or only destructive process occurring. © 2007 Wiley Periodicals, Inc.     

Monitored natural attenuation forum: State of the practice—Highlights from a breakfast discussion

The Monitored Natural Attenuation (MNA) Forum is published as a column in each issue of Remediation. The format typically includes one or two questions related to MNA with responses from several MNA Panel members. This column highlights MNA topics discussed at a breakfast held in support of the MNA Forum. It includes thoughts from various MNA Panel members and other environmental professionals who attended the breakfast on the “state of the practice.” © 2005 Wiley Periodicals, Inc.     

Accelerating environmental cleanup at DOE sites: Monitored natural attenuation/enhanced attenuation—A basis for a new paradigm

The U.S. Department of Energy is conducting a project to accelerate remediation through the use of monitored natural attenuation and enhanced attenuation for chlorinated ethenes in soils and groundwater. Better monitoring practices, improved scientific understanding, and an advanced regulatory framework are being sought through a team effort that engages technology developers from academia, private industry, and government laboratories; site cleanup managers; stakeholders; and federal and state regulators. The team works collaboratively toward the common goals of reducing risk, accelerating cleanup, reducing cost, and minimizing environmental disruption. Cutting‐edge scientific advances are being combined with experience and sound environmental engineering in a broadly integrated and comprehensive approach that exemplifies socalled “third‐generation R&D.” The project is potentially a model for other cleanup activities. © 2004 Wiley Periodicals, Inc.     

Application of source removal and natural attenuation remediation strategies at MGP sites in Wisconsin

This article presents site closure strategies of source material removal and dissolved‐phase groundwater natural attenuation that were applied at two manufactured gas plant (MGP) sites in Wisconsin. The source removal actions were implemented in 1999 and 2000 with groundwater monitoring activities preceding and following those actions. Both of these sites have unique geological and hydrogeological conditions. The article briefly presents site background information and source removal activities at both of these sites and focuses on groundwater analytical testing data that demonstrate remediation of dissolved‐phase MGP‐related groundwater impacts by natural attenuation. A statistical evaluation of the data supports a stable or declining MGP parameter concentration trend at each of the sites. A comparison of the site natural attenuation evaluation is made to compare with the requirements for site closure under the Wisconsin Department of Natural Resources regulations and guidance. © 2003 Wiley Periodicals, Inc.     

Historical analysis of monitored natural attenuation: A survey of 191 chlorinated solvent sites and 45 solvent plumes

A survey of experts in the application of natural attenuation was conducted to better understand how monitored natural attenuation (MNA) is being applied at chlorinated solvent sites. Thirty‐four remediation professionals provided general information for 191 sites where MNA was evaluated, and site‐specific data for 45 chlorinated solvent plumes being remediated by MNA. Respondents indicated that MNA was precluded as a remedy at only 23 percent of all sites where evaluated as a remedial option. Leading factors excluding MNA as a remedial approach were the presence of an expanding plume and an unreasonably long estimated remediation time frame. MNA is being used as the sole remedy at about 30 percent of the sites, and 33 percent are implementing MNA in conjunction with source zone remediation. The remaining sites are implementing MNA with plume remediation (13 percent), source containment (9 percent), or some other strategy (16 percent). © 2004 Wiley Periodicals, Inc.