HARPER RIVER DIVERSION.

Press, Volume LVII, Issue 17206, 25 July 1921, Page 6

HARPER RIVER DIVERSION.

INSPECTION OF WORKS. VISIT OF PROGRESS LEAGUE OFFICIALS. On Saturday, July 16th, the worst thunderstorm experienced for a number of years burst over the Lake Coleridge district, and, n9 a result, the Harper river diversion works, by means of which the water from that stream was turned into, the lake, gave way, a fresh which turned into a flood proving altogether too much for them. Such a contingency was foreseen by the officials of tho Canterbury Progress League some months ago, when it wa9 suggested by the Government that the permanent diversion works, which, it nad been proposed; should not be proceeded wi th, owing to the financial stringency, and that the temporary works mentioned above should suffice. Having heard that these works had broken through, Messrs A. G. Henderson and P. R. Climie, president and organising secretary of the Canterbury Progress League respectively, accompanied by some Press representatives, made a visit to the site on Saturday, with a view to ascertaining how true the report was. They also visited the intake to the tunnel, through which the water enters to reach the power-, house, and the surge chamber. From a neighbouring hill the party was able to -see where the Harper h"ad broken through. This had occurred a short from the diversion works, the river going back to an old course at the far side of its bed, so that only a trickle was reachibg the intake to the lake. Perhaps the volume of water from this source would equal about 15 cusec'a (cubic feet per second). The ordinary. staff was four men, who had been left as a maintenance gang. They managed on Saturday about noon to make another temporary inlet toAhe diversion a little further up stream, and it was expected that, allowing for percolation from 100 to 130 cusecs would be flowing into the intake by midnight on Saturday. To-morrow a gang of twelve men is expected to arrive at the Harper to commence on the new temporary diversion works, just below the site of the origin- ■ ally proposed permanent works. This will involve the construction of ft groyne, and it is anticipated that the work will be completed in from a month to six weeks. If successful, the scheme should result in the water being thrown to the near (or Christchurch) side of the riverbed and entering the intake to the lake from the left, instead of the right side. The scheme, that is at present only contemplated, necessitates the building of a big dam across the riverbed at a ♦ point which would enable it to catch all the water, of the Harper, and abo of the Wilberforce, if the latter stream could be so diverted as to make it flow down a gully which woul' bring it into the Harper some distance higher up than the present confluence of the streams At present there are four units in use at the power house, each o'f a capacity of 1500 kilowatts, served by two pip* lines. The third' pipe-line was completed by the contractor about two weeks ago, and is now in the testing state. The new unit at the power house is drying off and should lbe in active commission by the end or August. This is the most powerful unit yet installed, 'having a capacity of 3000 kilowatts, or twice as much as each of the others. Tho fifth unit will bring the capacity of the power station to 90CO kilowatts. 'The two pipe-lines at present in commission take a maximum load of 200 ciisecs and the third pipe* line will take another 100. Allowing for the decrease in the demand for electricity at different times of the day, the average consumption of water through the two pipe lines is 150 cusecs. The third pipeline will probably consume about 70 cuseft, making a total consumption of 220 cusecs for the 24 hours, The contract for the fourth pipe line has been let to a Dunedin firm, which had the contract ,for the first two pipe-lines. The sixths unit of 8000 k.w. is now on order, and it is expected to be ready by the time the fourth line is com l pleted, which Bhould be in about 12 months' time. At present the preliminary survey work is being carried out in connexion with the duplication of tho power house, and including _ a second, tunnel and four additional pipe lines; the contract for the latter will be let one at a time. Since the beginning of March, when the Lake was at its lowest level, about ,8 feet below normal, it has risen to the extent of 8 feet 5 inches. So far. the added supply of water from the Harper has provided sufficient for the station, and as much again for storage. Prom January to June there is generally a steady increase in the levei of the lake, while from the latter month to September there is a tendency to fall; then, with the melting of the enow, there is usually an increase to December. This year, for the, first time in five years, instead of decreasing, the lake has increased, bo that the temporary works, have proved themselves a success. Had they not been carried out when they were, the power station would no doubt have been out of commission by last month* At the time the water was first turned in, there was only two or three months supply on hand. In discussing the "matter with a 'Tress*' reporter, Mr Henderson said that the break through had shown that the League was justified in the position it took up with regard i to the Public Works Department "gambling on the works holding until those of a permanent nature were constructs. Had the break occurred in March, the position would have been very serious for the people of Christchurch.