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A WORKABLE DEFINITION OF SUCCESS
Citation:
Wilson*, J T. A WORKABLE DEFINITION OF SUCCESS. Presented at 2003 AFCEE (Air Force Center for Environmental Excellence) Technology Transfer Workshop, San Antonio, TX, February 25, 2003.
Impact/Purpose:
To inform the public.
Description:
The most desirable definition of success from the point of view of environmental stewardship is to treat the entire plume to MCLs. Technically, has proven impossible to attain at many sites. A less desirable definition of success is to contain the source of contamination and treat the plume outside the "hotspot" to MCLs. There are O&M costs associated with maintaining containment, and liability associated with the continued presence of the hazard. However, this definition of success is the definition that has been most commonly attained at Superfund enforcement actions. An alternate definition of success is often attained in the underground storage tank program. After remediation, the plume is confined to the NAPL source area by natural processes. There are no additional O&M costs associated with maintaining containment. Definitions of success based on plume behavior, such as a stabilized or receding plume, depend on a statistical evaluation of plume behavior. It is often difficult to make a convincing case. Because the job is not done, these definitions are often unacceptable from point of view of stewardship.
As a general perception, technologies that achieve less than 50% reduction in contaminant concentration are considered failures, technologies that achieve more than 70% reduction are considered promising but require more development, technologies that achieve 90% reduction are considered to be successful, and technologies that achieve more than 99% reduction are considered substantial successes. Only 20% of chlorinated solvent sites can be brought to closure with 99% removal, half the site require 99.9% removal or more, and at least 15% of sites require at least 99.99% removal. Many innovative, cutting-edge, state-of-the-art approaches to site remediation can produce disappointing results. The site is cleaner after remediation, but not clean, and the immediate product of remedial activity is a need for more remediation. The definition of success for a remedial technology should be driven by the need to achieve closure at a site, not by the need to develop information about the performance of the technology.
A workable definition of success usually invokes a combination of active source control or source remediation, with plume remediation or monitored natural attenuation.
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