New Tunnel Line Determined

Press, Volume CVIII, Issue 31755, 12 August 1968, Page 22

New Tunnel Line Determined

(N.Z. Press Association) ROTORUA, Aug. 11. Two major tunnel falls in the last few months have forced a slight deviation from the original line in the Tawhitikuri - Whakapapa tunnel on the Tongariro power development scheme.

The Ministry of Works, in releasing the decision, also said that special precautions were being taken to avert further falls.

The tunnel is part of 10 miles of tunnelling on the western diversions project, which will divert the headwaters of the Wanganui River and tributaries into Lake Rotoaira where it will go through another tunnel to feed the Tokaanu powerhouse. The first of the major falls occurred on May 17, bringing down about 2000 cubic yards of debris and burying more than $lOO,OOO worth of equipment. Another fall at the same face occurred on July 16. Debris has been removed from the tunnel to within 150 ft of the old face and it is at this point that the tunnel now deviates from the original line. Work has started on the deviation. It will take a gradual Sbend for about 150 ft before entering a straight course to rejoin the planned line. The special precautions

which are being taken include investigation drilling ahead of the face. The drilling would intercept ground water and also give accurate indications of the conditions which can be expected.