Preliminary geological report on the Pukaki high dam site, covering geotechnical investigations since 1964 and geology exposed during excavations to early August 1972

SKU:
EG_139-pdf
$15.00
(Inc. GST)
$13.04
(Ex. GST)
Write a Review

Read, S.A.L. 1972 Preliminary geological report on the Pukaki high dam site, covering geotechnical investigations since 1964 and geology exposed during excavations to early August 1972. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 139 46 p.

Abstract: The Pukaki High Dam will be founded entirely on glacially derived materials. The site is very slightly upstream of the end of the Tekapo terminal moraine loop at the southern end of Lake Pukaki (S100). Correlation of the results between different methods of subsurface investigation that have been used in the past is very difficult. A broad geological history of the area is known, however the stratigraphic relationship of some of the units under the dam is not known. The major potion of the dam will be founded on proglacial lake deposits with the wings on Tekapo till and Mt John outwash gravel. The proglacial lake deposits are divided into three geological units. The contorted sediments gravel which is the oldest unit and exists predominantly below invert level. The contorted sediments member which consists of heavily contorted sand and silt. The fancy sands member, which has the Pukaki ''pug'' as a sub unit. The dam foundations are dry, although small perched water tables exist. A pernament water table probably exists under the dam between R.L. 1400' and 1450'. The recharge conditions of this water table are unknown. The different responses of gravel and the contorted sediments member to loading are not known. The thickness of very low pereability materials upstream of the dam is also unknown and outwash gravels may provide a leakage path when the lake is raised. (auth)