Design and construction of a low-level waste shallow land burial experimental facility

Abstract

The Environmental Sciences Division (ESD) of the Oak Ridge National Laboratory (ORNL) has been investigating improved shallow land burial (SLB) practices for disposing of low-level radioactive wastes in humid environments. Two improvements currently being studied are the use of a cement-bentonite grout applied to waste trenches before they are covered and the use of an impermeable Hypalon fabric liner, which completely surrounds the waste in a trench. A field-scale demonstration site, known as the Engineered Test Facility (ETF), has been established for these studies in the complex geologic setting typical of the Oak Ridge area. Design of the ETF was initiated in 1980 for purposes of (1) evaluating the ability of the grouted and lined trench treatments to minimize water contact and concurrent waste leaching, (2) evaluating selected waste disposal site characterization criteria, (3) integrating site characterization data into model development, and (4) validating the ETF site model and using it to predict long-term site performance. A total of nine trenches (six treated and three control) were excavated at the site in June of 1981. Bales of ORNL compacted waste were used to fill the 3m x 3m x 3m trenches, and, after treatment, all trenches were closed (backfilled andmore » covered) according to current practice. Evaluation of the trench treatments is in progress using a series of inorganic and organic tracer tests designed to monitor water movement in three regions of interest: the trenches, the unsaturated zone around the trenches, and the saturated zone below the site. A successful demonstration of reduced waste leaching resulting from either of these two trench modifications described in this design and construction report will have immediate application to larger disposal sites having similar water-related problems. 9 references, 14 figures, 3 tables.« less