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An Approach for Evaluating the Progress of Natural Attenuation in Groundwater (Web Conference)
Citation:
Wilson, J. An Approach for Evaluating the Progress of Natural Attenuation in Groundwater (Web Conference). Presented at Groundwater Resources Association of California GRACast Web Conference, August 30, 2012.
Impact/Purpose:
Presentation for the Groundwater Resources Association of California GRACast Web Conference on Thursday, August 30, 2012 from 12:00 pm to 1:30 pm Pacific Daylight Time.
Description:
Monitored Natural Attenuation (MNA) is widely applied to ground water contamination at hazardous waste sites. Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), MNA is considered to be a remedy like any other remedy. When MNA has been selected as a remedy, concentrations of contaminants in the groundwater are expected to achieve a clean-up goal at the site within a reasonable time frame. At many CERCLA sites, the time by which the goals are to be obtained is specified in the Record of Decision (ROD). At CERCLA sites, the performance of the remedy or combination of remedies that were selected under the ROD is reviewed every five years. At present, there is no generally accepted approach to evaluate long term monitoring data and establish a time by which clean-up goals should be attained. At present, there is no generally accepted approach that can be used to determine whether the extent of attenuation within a particular five year review period is adequate to allow the site to attain the clean-up goal at the site within a specified time frame. U.S. EPA recently released a report that addressed these issues [An Approach for Evaluating the Progress of Natural Attenuation in Groundwater EPA 600/R-11/204 www.epa.gov/ada]. The report presents a simple, statistically based approach for evaluating the progress of natural attenuation from the data collected during site characterization and long term monitoring. The report provides an approach to establish the time that should be required to attain the clean-up goals, and an approach to evaluate attenuation within a review cycle to determine whether attenuation within that period of time is adequate to allow the site to attain the ultimate clean-up goal by a specified time. This presentation will review the key aspects of the approach to evaluate MNA as presented in the report, and will illustrate the application of the approach by applying the associated computer applications to examp