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As represented by the graphic above, traditional site characterization begins with a site investigation, where investigators first examine historical records to find out what's gone on, who's been responsible, or how the material was disposed of.

A plan is then written which specifies where and how many samples will be taken. In most cases, samples must be sent off site to a laboratory using approved methods of analysis, requiring weeks to months for results to return.

Results may indicate a need to expand the scope of the work by collecting more samples or taking samples in a different location, and this requires returning to the site for a second phase of work. In addition, this requires writing a second work plan,which must again be approved by regulators and site owners. As the process cycles on and on, characterization can take years.

Like the traditional approach, ESC involves an initial investigation, stressing the importance of thoroughly investigating the history of the site by doing such things as interviewing former employees, researching past operations, and studying historical documents and photographs. The objective is to develop a coherent understanding of the probable character of the site so that contaminant locations can be more accurately predicted before the field work begins.

From this point on, the ESC approach differs from the traditional approach with the development of a dynamic work plan, which is designed to comprehensively address all aspects of the site characterization. As opposed to the traditional approach which is less comprehensive and more rigid and does not allow for daily data integration, ESC directs the application of environmental characterization technologies within a flexible decision-making framework. This aspect of the ESC approach is in many way similar to the Observational Method that has been applied in geotechnical engineering for the past several decades. (Peck, 1969, and Morgenstern, 1994).

ESC stresses three types of data aquisition: geophysical, qualitative analytical(screening) and quantitative analytical. ESC promotes a heavy reliance on geophysical characterization and qualitative contaminant analysis in the early phases, followed by on-site quantitative analysis. This differs from the traditional characterization approach which may or may not incorporate geophysical or screening data at this level.

Within the ESC approach, data is integrated on a daily basis and that new knowledge is used to modify the work plan, thus allowing the project manager to choose which technologies to use and where to use them to fill any apparent data gaps. This results in a more rapid use of resources up front, but in the end results in a more efficient process.

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Last Modified: 1 January 2002 by dave eckels
Expedited Site Characterization: etd/technologies/projects/esc/new.html