Evaluation of Leachability of Radium Contaminated Soil

Composite samples of radium contaminated soil were batch extracted at pH 5 and pH 3 in a modification of ASTM Test Method for Shake Extraction of Solid Waste with Water (D 3987-81) to evaluate the relative leachability of radium-226 from soil which had been blended with a non-contaminated soil, in order to achieve approximate background concentrations of radium in the soil mix. Comparisons were made between contaminated soil, diluent soil and the resulting amended mix. Analysis for radium was conducted by de-emanation of radon-222. Data from the extractions were used to evaluate a bench-scale demonstration of soil blending, which was judged to be a technically feasible disposition alternative for soil contaminated with relatively low levels of radium. Comparison of the contaminated soil extraction values of radium with the radium concentrations detected in monitoring wells placed within the area of contaminated soil, indicated a tendency for the extraction tests to overestimate the concentration of radium actually seen in groundwater associated with the soil being evaluated. Extraction values were then used in a simple analytical groundwater model, incorporating only transport and dispersion, which predicted a maximum radium value well below all concentration limits deemed acceptable by present regulatory standards.