Corrosive water: a case history of two underground powerhouses

Water infiltration into powerhouse cavern of La Grande-2-A dam proved to have a relatively strong flow and was moderately acidic and corrosive in nature. The problem was encountered where the rock mass was affected by a system of faults. The remedial measures undertaken to repair and protect under corrosion were described. The study indicated that the acidity was due to the decay of pyrite, which is present in the fault zones. The damage could be controlled with proper protection of the exposed metallic parts. Since the acidic water was getting mixed and diluted with normal infiltration water from other part of the powerhouse complex, there was no concern for damage to the pumping equipment. The net pH of the pumped out water was such that there were no environmental implications. 2 tabs., 7 figs