Projects & Programs
Geostatistical Mapping of Contaminated Groundwater at the Hanford Site, Southeast Washington
Objectives: To use geostatistical methods to map the concentration of tritium, radioactive iodine, technetium-99, and uranium in contaminated groundwater, and to provide estimates of the uncertainty attached to those maps. To assist in the design of a groundwater monitoring plan for the site that will ensure proper tracking of the contaminated groundwater plumes.
Approach: Employed variogram analysis of concentration data to provide quantitative models for the spatial distribution of the contaminated groundwater plumes. Sequential Gaussian and indicator simulations of the contaminant concentrations were then used in a Monte Carlo approach to provide refined geostatistical estimates of the contamination at the Site, and the uncertainty associated with those estimates throughout the mapped area.
Results: Maps were produced for the client that provided estimates of the concentration of contaminants in the groundwater for each grid block in the map area. Maps showing confidence intervals for the concentrations in each grid block were produced, as well as maps that showed the probability that the concentrations would exceed the drinking water standards for each contaminant. The probabilistic maps were used to evaluate all monitoring locations in the region to determine which would be most suitable for continued monitoring, as well as identifying new locations that would most reduce the uncertainty in mapping the edges of the contaminated groundwater plumes. The redesigned network allowed the client to identify the locations that provided the most valuable monitoring information at the lowest cost.