Big Dam at Arapuni

Sun (Auckland), Volume 1, Issue 38, 7 May 1927, Page 4

Big Dam at Arapuni

Flood Danger Overcome Power-House Remains a Problem

“We have now got to a stage where the dam is practically safe even if we do have a flood. In another week or so one of our biggest fears will be removed.” This statement was made to a special SUN representative, travelling with the Water Supply Commission party, by one of the engineers engaged on the Arapuni dam construction, at Arapuni yesterday.

Once, the gorge through which the Waikato River flows at Arapuni was inspiring because of the grandeur of the sight, but in the actual portion of the gorge that is being dammed this native grandeur is now replaced by the impressive work of man. The river which once rushed and thundered along a rocky bed- has been pushed aside through a huge tunnel, as a thing of no immediate consequence—so long as it does not floc-d, and the spectator now looks down the side of a precipice at men appearing to be as big as flies, working on the final section of foundation some two hundred and twenty feet below the bank level and many feet below the original level of the

Two huge cliffs of concrete are now stretching up from the depths on either side of the gorge to within a few feet of the final level of the dam, and, between these, another mass of concrete has been built up to 50ft. above the lowest level of the foundations, which have been sunk low in the river bed. “ALL TROUELES OVER, EXCEPT—”

It is above these that the final foundations are being sunk even lower into the bed of the river, and when the concrete has been let into the foundation now prepared, the engineers will have little cause to fear any threat from the river ,the new dam now being higher than the old dam used to divert the water into the underground tunnel. “Another week, and practically all our troubles will be over,” remarked the engineer, adding as an after-thought: “Except the powerhouse trouble/'

The actual dam has been moving ahead very rapidly lately, and between five and seven thousand cubic yards of concrete per month have been put in. It is expected that this rate of progress will be considerably improved after the next few days, when the foundation work has been completed. Members of the party were told that the dam would be completed or practically so in between five months and the end of the year. POWER-HOUSE DELAY

When the power-house will be completed is quite another question. It was learned that definite decision as to whether the power-house will be built on the site excavated or removed to another site, is expected to be made within the next month. As far as the question of- site is concerned the general impression among those connected with the work was that the difficulty in connection with the foundations on the present site would be overcome, and it would not be necessary to repeat the expense of excavating the great bay in the cliffs to accommodate the power-house. NOT TILL LATE 1928 Another impression however and one which gives rise to less hopeful antici-

pation. is that if the power-house is built on the site excavated at present the building- of the power-house will have to await the shutting off of the water by the main dam. Until the site earn be freed from water the soft spot cannot be dealt with.

The soft country has now been explored to over 120 feet below the river level without any foundation being secured.

As the building of the power-house is expected to take a year and the dam will not be finished until the end of this year, the expectations of power from Arapuni appear to be directed more to the end of 1928, than was provided for when the contract was let.

In the meantime the second dam to hold the water above the power-house is progressing very rapidly, and one of the spillways below the dam to prevent the overflow washing away the ground and endangering the dam foun-' dations, is nearing completion, while the boring of the Penstock intake tunnels is being finished off, and concreting and putting in of the steel pipes 12ft. in diameter is going forward.

HORA HORA POWER

MAY FAIL ANY MINUTE PLANT UNDER HEAVY OVERLOAD The power house at Hora I-lora Is constructed to produce a limit of 10.300 kilowatts. At present it is producing 12,500 kilowatts, an over-load of 2,200 kilowatts, or nearly 22 per cent, above capacity. It is carrying this load for 1G hours daily. “The next thing that will happen will be the busting of the whole plant," was the cryptical manner in which one authority expressed himself to a SUN reporter yesterday. Put in somewhat less technical terms this means that there is a possibility of a blow-out in the main feeder cables from the generating station at any moment, and such an event would mean that Hora Hora would be "closed for repairs” for a week or 10 days. “It' is imperative that something should be clone to restrict the load,” the informant continued. "The consumers are allowed an indiscriminate use of power, and we can’t go on supplying at the present rate.”

Everything possible has been done to keep up the highest possible supply, and the latest addition at the works is a traffic plate to direct the water round an awkward angle, in the dam, which had prevented a sufficient supply of water power to the No. 1 dynamo.