[en] The scope of this work includes an evaluation of certain trench cap designs, trench construction methods and trench loading utilizing structural and hydraulic monitoring methods under the stress conditions of an artificially created void space in the trenches representing decomposed waste. During the period of this report monitoring was continued on three (3) trenches at Mount Lemmon, Arizona and, in addition, a new trench was constructed with a wick design similar to those being tested in another USNRC project at Sheffield, Illinois. The new trench (Trench No. 5) also contains an improved soil beam design. Conclusions to date indicate that trench caps relying on either a single layer of fabric reinforcement or a non-reinforced soil beam will result in some eventual cap failure. The soil beam or soil arch are, alone, insufficient designs to prevent cap failure. There is insufficient data, as yet, to evaluate the soil cement reinforced beam. On the positive side, the experiment has demonstrated the value and use of tracers in understanding water movement in and around the trenches. Further monitoring will provide a better understanding of the cap failure mechanisms. 18 references, 17 figures, 13 tables