CITY WATER SUPPLY
WORK AT WAINUI-O-MATA
VISIT OF INSPECTION TO ORONGORONGO TUNNEL. INTERESTING OPERATIONS.
The progress being made with the tunnel boring contract at Wainui-o-mata, by means of which the city’s water supply is to be augmented and assured through the drier months of the year, was inspected yesterday by a party of city fathers.
The councillors were the guests of Mr Robert Semple and the gang of co-operative labourers to whom the contract for the construction of the tunnel was let by the corporation; two-thirds of the party, which included the Mayor (Mr R. A. Wright, M.P.) and several of the corporation officers, availed themselves of the invitation, and all derived much useful information from having witnessed the progress being made. All were likewise convinced with the sincere manner in which the contractors are proceeding with the stupendous task ahead of them, and were brought to realisation of the hardships with which the men are faced.
THE SCHEME OUTLINED.
A few words of explanation are necessary for the comprehension of the scheme. At present the city’s water supply is in the main derived from the Morton Dam, in the Wainui Valley, whence the water is brought by big mains to the town and suburbs. The growing needs of the city, however, demand that the reservoirs be connected up with a source of supply which will provide an adequate service to amply supply the consumption all the year round.
The scheme of boring through the great ridge which separates the Wainui Valley from the Orongorongo stream, in order to augment the supply in the present reservoirs from the latter river, was therefore conceived, and raising of money for the big contract was sanctioned by the ratepayers at a poll in December last. It is estimated that the scheme, when complete, will permanently ensure the city’s requirements.
GOOD PROGRESS.
Operations were commenced about a year ago, and considering the difficulties that the men have had to contend with, excellent progress has been made. Boring was commenced at a point about a mile above the Morton Dam, and a camp was pitched some hundreds of yards below the mouth of the tunnel, where the men—at present about fifteen in number—have their headquarters. The camp consists of a number of neatly and comfortably built cottages surrounding an adequate kitchen and dining room, all constructed with the best materials.
The initial work in connection with the piercing of the tunnel presented little difficulty, the face of the hill being found to consist of clay, which was comparatively easily worked. Latterly, however, rock was encountered, presenting such an iron-like barrier as to make further progress with the boring operations practically out of the question. Hand-drills were used until the hill had been entered to a distance of 225 feet, when it was decided to turn attention to incidental work pending the arrival of power-driven plant. For the past three months, therefore, the driving of the tunnel has been abandoned. The entrance has been heavily timbered up to prevent the collapse of the roof and walls, but the main tunnel will require no reinforcing.
“HARDEST IN NEW ZEALAND.”
The rock, in the opinion of Mr Semple and his comrades, who are all picked men and experienced miners, is the hardest in New Zealand, and resists the stoutest blow from a heavy hammer without the slightest impression being made. In the process of breaking it rings like steel. To penetrate a distance of one foot, forty drills are necessary before the charges may be inserted.
It takes two good hammermen eight hours to bore three feet into such resisting material with the ordinary man-power tools—hammer and crowbar. Much of the drilled rock is being used upon the roads around the camp; it resembles lignite, being of a blackish colour, and is described by the experts as a mixture of grey sandstone and a kind of “mongrel” granite.
“I only hope the city finances are as sound by the time the job is finished,” one of the councillors was heard to remark as he witnessed the effect of a steel hammer applied to the rock face.
THE MACHINERY.
The machinery for the generation of the power for the working of the drills is now being assembled upon a site a few yards below the big dam, where a turbine, to be driven from the overflow from the reservoir, and a steam plant will be erected. The turbine will be an 80 h.p. engine, and will create compressed air to feed the drills and also ventilate the tunnel, which is to be about two miles in length. The water power will be available for about seven months during the year, and in the dry season the steam plant will be requisitioned.
The engineer in charge of works (Mr Barranci) anticipates that the machinery will be in motion in from two to three months’ time.
TRACK CONSTRUCTION.
The men are at present engaged upon the construction of a track over the mountains preliminary to the commencing of boring operations from the Orongorongo side. This work is fraught with difficulty. The hillside is densely covered with heavy bush, and the track on the eastern side, which zigzags to the summit, a height of 2500 feet above sea level and 2000 feet above the present camp, has an average grade of 1 in 4.
Two months should see the completion of this rough road, which is now far down on the other side of the range. When finished another camp will be pitched in the Orongorongo valley for the men working at the western mouth of the tunnel. Stores and materials are being daily trekked over the hill by horses. Not the least arduous part of the day’s work at present consists in toiling muddily over the hill through the bush to the scene of operations.
STRENUOUS WORK.
The men set out at about 6 o’clock in the morning, trudge the long journey to the workings, put in an eight-hour day, and return to camp by the same devious route. Only the strongest and hardiest could survive such a life, and several members of the party who walked half the way to the summit were forced to admit, one and all, that none but athletes could, day after day, complete the journey. The track had been rendered none the easier by an inch of rain and snow which fell in the valley on Tuesday last.
Dinner and afternoon tea were handsomely provided for the visitors at the camp by the miners’ wives; all were impressed with the quality of the viands, vegetables and milk, which are mostly supplied to the camp by surrounding farmers.
At the conclusion of afternoon tea the Mayor rose to express thanks on behalf of the party for the hospitality extended, and to congratulate Mr Semple and his partners upon the great work they were performing. Mr Wright went on to refer to the satisfactory progress being made with the contract. His remarks in this connection are reported elsewhere.
