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Site characterization to support risk assessment of contaminated ground-water- some case studies
Citation:
WILSON, J. T. Site characterization to support risk assessment of contaminated ground-water- some case studies. Presented at Academic Exchange Center, China University of Geosciences, Beijing, CHINA, October 11 - 17, 2008.
Impact/Purpose:
Identifying important causes of uncertainty and error in estimating the impact of contamination on drinking water wells.
Description:
In the USA, “risk assessment" generally refers to an evaluation of the impact of a known concentration of a hazardous material in ground water on human health or environmental quality. This presentation is different. It deals with the impact of a spill or release of hazardous material on the water produced by a drinking water well. The emphasis is on an accurate definition of the location and behavior of a plume of contaminated ground water, to prevent future contamination of drinking water wells. There are three important causes of uncertainty and error in estimating the impact of contamination on drinking water wells: (1) inadequate characterization of the primary directions of ground water flow in the vertical plane (plume diving), (2) inadequate characterization of the primary directions of ground water flow in the horizontal plane (3) Inadequate characterization of the vertical co-distribution of non aqueous phase liquids (NAPL), the contaminants in ground water, and the electron acceptors in ground water that support natural attenuation of the contaminants. In the presentation, a case study illustrates the use of electrical conductivity probes to evaluate and predict plumes diving, case studies illustrate the use of the software application OWL to estimate and characterize changes in the direction of ground water flow, and a case study illustrates the vertical distribution of hydraulic conductivity, and vertical distribution of residual NAPL contamination on the formation and natural biodegradation of a plume in ground water.