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Fig. 11. (A) During wet conditions, such as spring snowmelt or prolonged precipitation events, residual RDX is flushed through the vadose zone and alluvial system. RDX is stored in fine-grained sediments in the canyon bottom and in the tuff matrix, surge beds, and fractures. More flow paths are active during wet periods, and some of these flow paths may bypass the alluvial groundwater and enter the stream channel directly. Barite will remain insoluble while witherite can dissolve following influx of fresh water. (B) Under dry conditions RDX is isolated in unsaturated fine-grained sediments and the vadose zone. As the alluvium dries, witherite and barite precipitate.
