Field sampling for monitoring migration and defining the areal extent of chemical contamination

Initial research on compositing, field designs, and site mapping oriented toward detecting spills and migration at commercial low-level radioactive or chemical waste sites is summarized. Results indicate that the significance test developed to detect samples containing high levels of contamination when they are mixed with several other samples below detectable limits (composites), will be highly effective with large sample sizes when contaminant levels frequently or greatly exceed a maximum acceptable level. These conditions of frequent and high contaminant levels are most likely to occur in regions of a commercial waste site where the priors (previous knowledge) about a spill or migration are highest. Conversely, initial investigations of Bayes sampling strategies suggest that field sampling efforts should be inversely proportional to the priors (expressed as probabilities) for the occurrence of contamination