ARAPUNI TUNNEL.

Taranaki Daily News, 10 June 1932, Page 2

ARAPUNI TUNNEL.

SECOND SLUICE-GATE,

ARRIVAL OF FIRST SECTIONS.

Portions of what will be probably the most heavily-loaded’ bluice-gate in the world, constructed or ■ projected, .the; Np. 2 gate for the Arapuni hydro-electric works, are aboard the Karamea, which is due at Auckland from Ljverpool. The gate has been shipped in sections, including 10 five-ton lifts and one 10-ton

lift. ’ x The installation of a second gate in the diversion tunnel at Arapuni has been undertaken on the recommendation of Professor Hornell, the Swedish expert who was engaged to advice the Government on' the repairs which should be undertaken at the works. .'A description of the gate was given in a' recent edition of the Trade, and Engineering Supplement of the Times, which said:. ■ r “Professor Hornell stated that, in his view the rupture in the headrace was primarily due to the entrance' qL.jvater into the rock through capillary Action, which caused it to swell and exert an enormous bursting force. Accordingly, he recommended that an. impervious, lining should be given to the whole of the headrace to prevent the water from coming into contact with the absorbent rocks, and also that a further gate or gates should be installed in the diversion. tunnel to act as guard sluices for those already in existence, in view of Jhe importance of always maintaining the tunnel prepared for use in the event of the necessity arising to expose the headrace for inspection or repairs to the lining. ■•••/.’. * “Soon after this report was made the New Zealand Public Works Department requested Messrs. Glenfield and Kennedy, Kilmarnock, to design suitable equipment. After study of the problem they decided to recommend a single free-rollar tunnel sluice-gate in preference: to two, in order to weaken the country in. the region of the shafts as little as possible. The dimensions selected for the gate were 24ft span by 20ft height.’ It.will | operate under a head of 158 ft, and the Water pressure on the face will' amount to over 2000 tons, making it probably the most heavily loaded sluice-gate in the world, constructed or projected. , “The gate, which is of . the milkers latest design for installation, in a dry well, has self-releasing side s taunching arrangements on the upstream side, which can be adjusted into close contact with their respective faces on the built-in frame while the gate is. closed and under pressure, and relieved from contact when the gate begin? to. lift, the lintel staunching, also being adjustable under pressure. Operation is. by means of hydraulic power,. one central I cylinder, situated at ground level, ing connected to the gate . by. two ..lifting rods and compensating . arrange-; meuts.

“Four tie-bolts pass' completely, through the gate to the bottom member,, the upper ends terminating ,jh two; articulated beams connected to the lifting rods. The gate itself weighs oyer 80 tons, and its total weignt' with, .its; attendant equipment exceeds 300 tons. ->■ “The gate was erected in the shops of ! the makers at Kilmarnock, but,-it was; to he dismantled and despatched to,New Zealand.”