Role of Trench Caps in the Shallow Land Burial of Low-Level Wastes

摘要

Experience dating back to the early 1940s clearly documents the importance of isolating waste disposed of by shallow land burial from the biosphere. While no significant threat to the health and safety of the public has occurred to date, poor facility siting and/or design has resulted in a number of sites failing to perform as predicted or in an acceptable manner. The trench cap may be the single most important component of the LLW disposal system. It must effectively isolate the waste from the biosphere by controlling infiltration, gaseous emissions, and biointrusions. At the same time, a number of other forces (i.e., erosion and subsidence) are acting to destroy its integrity. Results of experiments and operational experience to date indicate that while one design feature may be effective at controlling one problem (e.g., cobble-gravel effectively controls biointrusion), that same design feature may be ineffective or actually exacerbate another problem (e.g., cobble-gravel may allow increased infiltration rates). Therefore, trench cap design must evaluate the systems effects of the various options either using intuitive methods as is currently the case or by using mathematical models which are currently being developed and validated. 36 references. (ERA citation 09:025516)