PNNL

Abstract

This paper describes results from intermediate-scale, two-dimensional testing of foam injection into sedimentary materials collected from the U.S. Department of Energy (DOE) Hanford Site area. The testing was performed to evaluate the transport of new, more robust, foam generation formulas developed by PNNL on field applicability. The mechanisms of transport , foam stability, delivery pressure, foam migration and the ability of foam to deliver remedial amendments for stabilization of uranium contamination were evaluated. Testing was accomplished in a test bed that is designed to focus on two-dimensional flow, in the form of two, thin rectangular boxes. Each of the boxes holds approximately 135 liters (255 kilograms) of sediment. A total of six sets of tests have been conducted, the last two of which will be described here. During the fifth and sixth tests, foam, generated by means of mechanical blending, was injected into the central screened segment of the left side of each box while air was extracted from multiple screened segments along the right side of each box. During these two tests both of the boxes were loaded to contain a rectangular zones of fine material and a rectangular zone of coarse material . Portions of the sediment were augmented with uranium-rich calcite to produce known concentrations of uranium. The foam generating formulas used in both tests contained sodium phosphate and sodium tripolyphosphate as a remedial amendment. Subsequent to each of the two tests, the test beds were disassembled, and samples of the sediments were taken and analyzed for a number of parameters, depending on the specific test. The data indicated that uranium contamination may be successfully immobilized and that that directional movement of the injected foam can be controlled.