A great deal of dust was being created at the site where the extraction belts were dumping the tunnelling debris, in spite of the cowling, especially when the work face was going through waterless, limestone-heavy areas. The ground-up dry debris were falling from the belt onto waste heaps where they lay awaiting loading and shipping to the dump, and the falling debris were sending up a column of dust that could be seen from the road, although it did not affect the nearby population centre.

Construction of an enclosure covered by a sheet-metal roof, with sides that could be opened for lorry and loader access and kept closed when loading was not under way. Debris were dumped from a hopper outfitted with water sprinklers at the end of the belt, well inside the enclosure.

Optimum results were obtained. The dust cloud disappeared.