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Section 3: Site investigation techniques |
1 Chevron Research and Technology Company, Room 10-3650, PO Box 1627, Richmond, California 94802-0627, USA
2 Fugro Geosciences, Inc., 6105 Rookin, Houston, Texas 77074, USA
Before we can hope to successfully conduct a risk assessment, or select the proper technology for remediation at a contaminated site, we must first have a thorough understanding of the nature of the impacts at that site. This paper will present an overview of a field-proven, in situ site assessment technique based on laser induced UV fluorescence, that provides continuous, real time information on the distribution of hydrocarbons in the subsurface. The system can detect hydrocarbons regardless of whether they are located above or below the water table, and it gathers the data without generating any cuttings that could require costly disposal. This technology can also provide a qualitative ‘fingerprint’ of the hydrocarbons present at the site. Since the data are available in real time, adjustments to the site assessment programme can be made in the field. Examples of applications of this technology include using it as a screening tool to delineate both the horizontal and vertical extent of hydrocarbon contamination; estimating the volume of contaminated soil that may have to be addressed; or helping to select locations for more expensive confirmatory soil samples or permanent monitoring wells. Actual data from a number of sites will be presented to illustrate some of these applications.
