Hancox, G.T. 1976 Waikato power development, geological investigations for the proposed Arapuni B power project (stage 1 : May 1975-March 1976). Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 245 47 p.
Abstract: In this report the geology of the Arapuni area is described and the results of recent drilling investigations for the proposed Arapuni B Power Project are presented. The results indicate generally favourable foundation conditions for all of the major structures, the only likely problems being the depth of overburden at the proposed powerhouse site and on the penstock slope, and the necessity to ensure an essentially watertight headrace canal. The powerhouse will be founded on a uniform surface of sound, massive pumice breccia (Ongatiti Ignimbrite) which is at least 15 m thick at the proposed site. Spillway Alluvium will not be encountered in the foundations. Excavation at the site will necessitate the removal of the sand and gravel overburden from below the water table where sheet pile protection and well-pointing techniques may be required. Addition design stage drilling investigations and possibly early stripping of the penstock slope are recommended to provide further information on rock condition in the critical areas at the back of the powerhouse and at the penstock slope. (auth)
