Gulliver, C.P. 1977 Rangipo headrace tunnel, progress report on engineering geology. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 290 12 p.
Abstract: Construction of the 8 km long, 4.5 m diameter, Rangipo headrace Tunnel commenced in March 1976. The headrace tunnel will comprise part of the Rangipo Power Project and will convey water diverted from the Tongariro River and the Rangipo underground powerhouse. This report summarises engineering geological aspects of the tunnel construction to the end of MWD Construction Period 155 (14 September 1977). The tunnel is being excavated using the conventional drill and blast method. Primary support is provided by steel sets and timber blocking. Since tunnel construction commenced rock conditions encountered have been recorded in detail, and surface geological mapping has been carried out along the tunnel route. In addition to describing progress on these aspects the report also comments on anticipated tunnelling conditions ahead of excavation. (auth)