Engineering geological investigations at the Scheme F Clyde damsite

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Thomson, R. 1978 Engineering geological investigations at the Scheme F Clyde damsite. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 316 18 p.

Abstract: Geological mapping and diamond drilling investigations to determine a satisfactory site for the Clyde Dam are nearly complete. The favoured site (Fig 3) is slightly upstream from several alternative sites originally reconnoitred for a low dam and later initially investigated for the Scheme F high dam. Persistent foundation discontinuities are expected to be widely spaced. A fault zone, trending along the left side of the river channel and dipping beneath the left bank, is the only major feature positively identified. Significant structural defects can be inferred in the vicinity of the right abutment but faults and crush zone located elsewhere appeared to be small. Joints are moderately to widely spaced and are probably tight at depth. The dominant set strikes approximately parallel to the valley and has a steep dip. Moderate weathering extends down to the water table and a zone of pervasive mineral alteration reduces the rock strength at and downstream from the spillway toe. Drilling in the vicinity of the proposed dam suggests that oxidation and alteration will not adversely affect the rock quality in the foundations, however. 

Note this report is not complete Figs 3, 5-7 missing