Geostatistical Sample Location Selection in Expedited Hazardous Waste Site Characterization

A geostatistical sequential sample location selection method is developed for Expedited Site Characterization or accelerated site investigations. The method provides a measure of the uncertainty regarding contaminant concentrations at unsampled locations on the basis of the existing contaminant concentration data. Sample locations are selected within regions where the probability that contamination exceeds a specified threshold indicates a high level of uncertainty. Samples are spaced according to the range of influence determined from a variogram developed from measured contaminant concentrations. Sample collection ceases when the contaminant plume is bounded by a probability contour indicating low probability that a contaminant concentration will exceed the threshold at unsampled locations outside the bounded region. The method is demonstrated with trichloroethylene data collected during an Expedited Site Characterization project at the U.S. Department of Energy Savannah River Site in 1995.