PROTECTION OF ARAPUNI.

Horowhenua Chronicle, 9 September 1929, Page 5

PROTECTION OF ARAPUNI.

ENGINEERS CARRY OUT PRELIMINARY TESTS. XO SERIOUS EROSION RECENTLY. (By Telegraph—Press Association.) HAAIILTON, This Day. Important tests have been made at the Arapuni hydro-electric works, the gates of diversion tunnel being raised three feet, releasing a considerable flow of water from the lake. The flow was so powerful that some bolts in the steel plates recently placed below the tunnel were loosened. The plates will be fixed more firmly. The engineers are confident that it will then be possible to release sufficient water to take away the flow from the spillway, to enable protective works to be carried out below the spillway, where erosion recently caused serious damage, undermining the spillway. It is reported that no serious erosion has occurred since August 21st. PROTECTION WORK WELL IN HAND. (By Telegraph —Press Association.) DANNEYIBKB, This Day. Respecting: the statement by Mr Holdsworth, chairman of the Auckland Electric Power Board, concerning the Arapuni erosion, the Hon. E. A. Ransom, Minister of Public Works, said it was exactly what he had known for the past six months. Remedial measures had boon taken in hand since his Ministerial visit, when he had realised that the waterfall scour was becoming a serious menace. At the then rate of progress it was calculated that it would take nine years for the falls to reach the spillway. Every succeeding fall at the mouth of the waterfall came down at a greater speed on reaching the spillway. The heaviest fall took place .about a month ago, and it was then realised that there was a possibility of having to de-water the lake to enable the Public Works Department to carry out the present work at the waterfall with the idea of reducing the water going over the waterfall. The Department had for some months shifts of men at work day and night driving penstock tunnels at the power-house so as to divert as much water a s possible through these tunnels. There were eight penstock tunnels to be driven when the scheme was recently completed, but it was only proposed to put through four of these for power purposes, which it was thought would meet the existing position. At present tunnels Nos. 7 and 8 were being pushed on, with a view of diverting as much water as possible. The by-pass tunnel at the dam was also being re-con-ditioned, so that as much water as possible might bo diverted from the lake down the old Waikato River course. The last fall at the waterfall was of a different nature to the previous, one, although very much greater, and did not reach the bottom of the fall, being more in the nature of \a eataract than a direct fall. It was hoped that, with the driving of the penstock tunnels and the partial opening of the bypass tunnel, that it might not be necessary to de-water the lake. Every precaution was being taken to divert the water if this was found to be necessary, and, should the by-pass tunnel have to be used, then it was likely that the lake would mL be allowed to be re-filled until the uc.lc at the waterfall had been placed i.i fi safe condition. It had not yet been finally decided what further work would be carried out, but probably the waterfall would be connected down tu the bottom of the fall.