Soil-bentonite slurry trench cutoff walls have long been used to control ground water flow and contaminant transport. Previous studies have shown that hydraulic conductivity of the soil-bentonite backfill is stress dependent. Furthermore, the stresses are dependent upon the load transfer generated by the formation sidewalls and the backfill consolidation and creep. The rate of consolidation is controlled by the flow out of the backfill into the formation, which is also stress dependent. These coupled phenomena are further complicated by the lateral deformation of the formation sidewalls during the various stages of slurry trench construction including excavation, backfilling, backfill consolidation, and backfill creep. The coupled mechanical phenomena are simultaneously occurring as the ground temperature changes. To fully evaluate the interactions between the various phenomena, a full-scale soil-bentonite slurry trench cutoff wall was constructed to a length of 660 m, a width of 0.9 m, and a depth of 6.2 to 7.1 m. Relevant to the phenomena discussed in this paper, the construction was instrumented with four pairs of inclinometers, four settlement plates, and four sets of earth pressure cells to measure total stresses in the backfill in three dimensions (i.e., vertical, horizontal longitudinal, and horizontal transverse) at four different locations within the wall. Each set of earth pressure cells was mounted on a cage with an accompanying pressure transducer and thermistor for pore pressure and temperature measurements, as well as sensors for roll and pitch. The study showed that the primary consolidation was complete approximately two weeks after wall construction. However, coupled phenomena consisting of lateral deformation, backfill creep and resulting settlement, pore pressure dissipation, temperature change, and load transfer were still occurring four months after wall construction. Effective stresses remain far below geostatic. The maximum stresses are those transverse to the axis of the trench from the impact of lateral deformations evident in the inclinometer data. The lowest stresses are the vertical stresses, reflecting the impact of arching or side wall friction as the soft backfill moves downward within the trench. Longitudinal horizontal stresses are intermediate between the transverse horizontal stresses and vertical stresses