The performance of every engineering and environmental company conducting operations at a hazardous waste site is directly dependent on their ability to provide accurate and correct information regarding the type and concentrations of hazardous wastes encountered on the site, yet their choice of geochemical analytical techniques, both in the laboratory and on-site are often relegated to a fairly low priority to save on cost, particularly for real-time screening devices.

In addition, EPA methods are often used even if inappropriate for analysis of the specific components. For example, the PID detector is most often the instrument of choice for onsite screening in spite of the fact that it more often than not yields erroneous information. Gas chromatographic, derivative spectrometers, UV fluorescence, and infared TPH techniques are compared and contrasted for applications involving volatile hydrocarbons, chlorinated solvents, and older, less volatile components such as aged diesel or fuel oil.

Plume maps constructed from soil gas data measured on specific, selected components offer a far more accurate and cost-effective method for defining the horizontal extent of most subsurface contaminants than are the limited number of boreholes usually deployed. Boreholes should be screened continuously and used primarily to determine the vertical extent of the contaminants encountered. Solvent extractions followed by high-resolution capillary GC methods are recommended to aid in the identification of the specific contaminants found and to determine relative ages and mixing of different products. This type of information is of particular importance during remediation. Numerous case studies will be used to demonstrate these concepts.

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