Low-level nuclear waste shallow land burial trench isolation. Annual report, October 1981-October 1982

The scope of this work covers an evaluation of trench cap designs, trench construction and trench loading by artificially speeding up the creation of void space in the trenches and monitoring structural and hydraulic effects under these conditions. Eight trenches were constructed and instrumented, four in a semi-arid region and four in a more humid mountainous region. The two main concepts being tested are the soil arch and the soil beam. Additionally, it is expected that methods will be developed for optimization of monitoring of sites as well as improved predictions of the relative long term stability of the tested designs. The results to date indicate that the soil beam and spoil arch are viable concepts that can be utilized in the design of shallow-land burial renches. The presence of geotextiles reinforcement does diminish the deleterious effects of moisture infiltration into the waste area. However, there are some contraints that may limit these applications to full scale, commercial operations. These constraints are: (a) need for moisture and soil match between trench sidewalls and backfill; (b) the maximum depth to width ratio of the backfill cap is dependent upon soil properties along the trench wall-cap interface; and (c) the soil beam should be sufficiently rigid not to slide off its end supports