ARAPUNI WORKS.

Otago Daily Times, Issue 21267, 23 February 1931, Page 8

ARAPUNI WORKS.

EFFECTING REPAIRS. FOURTH UNIT INSTALLED. POWER AVAILABLE IN IS MONTHS. (Special to Daily Times.) AUCKLAND, February 21. Steady progress is being made with remedial works at Arapuni. Four hundred odd men are engaged upon various tasks. Excavation is preceding apace, mostly at the falls and along the headrace. Hundreds of thousands of tons of earth have been shifted from the headrace by means of electric engines and dumped over the bank into the original riverbed between the dam and the entrance to the diversion tunnel. The channel has been cleaned out and the crack which appeared for nearly 1000 ft along the bed from the spillway has been explored and got ready for grouting with the concrete. The drain suggested by Professor Hornell to go in the bed of the headrace, beneath the concrete lining, to receive any seepage that may occur is now almost completed. A very important and large undertaking which was not contemplated in Professor HornelTs report is the narrowing and confining of the headrace channel. Hitherto the banks were undulating, enabling the water to spread out over an extensive area. On both sides the banks are now being built in by a grading process and the dumping of many thonsands of tons of earth from the higher land beyond. The idea is to form a channel of fairly even width, with gently battered banks. This will effect great economy in the concrete, besides giving a definite form to the channel, and will confine the waters within strict limits. At the falls preparations are being made for concreting. A large number of men are busy stepping the falls down, and with the aid of huge cranes and a Blondin ropeway they are cleaning out the bottom. Drilling is in progress along the foot of and on the upstream side of the dam, where the rock is being cut out to enable grouting with concrete. It is hoped by this means completely to seal the foot and stop the seepage which formerly occurred at the power house. Preparations are being made for the installation of a fourth unit to provide an additional 15,000 kilowatts. The machinery is uow_ a Putaruru, and when erected the capacity of Arapui will be brought to 60,000 kilowatts. The completed scheme provides, of course, for eight units, generating a total of 120,000 kilowatts. And when will Arapuni be in operation again? The question cannot at present be answered. There are so many problems to be overcome arid the possibility of unforeseen difficulties is so great that even the engineers in charge can give only a rough estimate, which they fix at 18 months.