Beetham, R.D.; Halliday, G.S. 1985 Kawarau River power investigations : engineering-geological feasibility investigations for the Waitiri Spur tunnel section KW28 to KW23. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 385 60 p.
Abstract: The Waitiri Spur tunnel section is a small part of a complex overall scheme involving canals and tunnels that has been proposed as one of five options to develop most of the available hydraulic head of the Kawarau River for hydro-electric power generation. This report describes the local and regional geology of the mid-Kawarau Gorge area in relation to the proposed dropshaft and tunnel which would be excavated through sheared and foliated schist having widely variable rock mass properties. Most known major defects pass across the tunnel line at moderate to high angles, but foliation shears folded within Waitiri Synform will persist for some distance along the tunnel and have a major influence on its construction. The 1.6 km long tunnel line section has been comprehensively investigated utilising 1.7 km of seismic refraction surveys, seven cored drillholes and field mapping. This used in conjunction with an extensive laboratory test data base of schist properties gives confidence that the probable range of tunnelling conditions and support requirements can be adequately anticipated