WATER SUPPLY

Southland Times, Issue 19170, 14 February 1924, Page 5

WATER SUPPLY

THE DUNSDALE SCHEME A TOUR OF INSPECTION BY INNVERCARGILL PARTY. A large party comprising the Mayor (Mr A. Bain I, the Town Engineer (Mr T. 0. Fox), Councillors A. Glass, P. Meek, J. Miller, H. J. Farrant, E. Sheehan. C. Broad and M. 11. Boyes, Messrs McPherson and Smith, of 1 the Forest Service, Messrs L. S. Graham and Simpson, representing the Fire Board, besides several private citizens, left the Town Hall in cars yesterday morning at 10 o’clock for Dunsdale, where the Council owns an extensive tract of land set aside as a possible site for a gravitation water supply for Invercargill. The day was beautifully fine and the trip out most enjoyable, and passed without incident, except for the fact that one councillor, in his little two seater, came to grief at, the Dunsdale ford, and had to be towed out of the water. After a light lunch at 11 o’clock the party walked up the creek for about four miles. The weather was extremely hot, and the residents of the district were not a little startled at the unusual spectacle of the City Fathers, perspiring but determined, filing across the hills behind His Worship, the Mayor. For those who were hot preoccupied with the sterner work of estimating the natural resources of- the place, the walk was a most pleasant one, as the wooded valley of the Dunsdale is already a great favourite with picnickers. At about 3 o’clock in the afternoon the party returned to the cars, where and plans were produced, and a weighty discussion held over the merits of the scheme. Unfortunately a heavy thunderstorm came on, putting an end to further deliberation, and a start was made oh the return journey. THE RESERVE. The Dunsdale reserve comprises in all 7,700 acres, granted to the Council by the Government some years ago. It comprises a strip of land about two miles wide, which follows the bed of the Dunsdale for about 7 miles, embracing practically the whole catchment area of this stream. The land is for the most part covered with bush and manuka scrub, which is an advantage as far as a water supply goes, as it retards the "run off” of the rainfall. The water in the stream is excellent for domestic purposes, and not "hard” as is the case with the present supply. Most of those who vlited the place were greatly impressed with its potentialiites, and the opinion was generally expressed that some substitute for the present pumping system was highly desirable. "It is only a matter of time,” said the Mayor, "and we must take this scheme up.” TOWN ENGINEER’S VIEWS. In conversation with a Times reporter Mr T. O. Fox, Town Engineer, said he was most favourably impressed with the natural advantages of the locality for the purposes of a gravitation water system. Doubt had been expressed as to whether there was a sufficient supply of water available, but he had taken 4 guagings at different places and at different crosssections of the stream, and bad found that 3,274,000 gallons were coming down per day, which was ample for the requirements. As the rainfall since October had been considerably below average, this was probably a low estimate. He did not think that the rain on the previous night had made much difference, as he had noticed that several tributary streams, which in time of heavy rain were evidently fair sized torrents, were now almost dry. In any case, the present rate oF discharge was sufficient to supply a population of 80,000 people. There was a natura basin there which would form an ideal reservoir, as it terminated at the lower end in a narrow outlet, which could very easily be dammed. At the bottom it was about 25 feet across and at the top 120 feet. The abutments were also of solid rock. A fifteen foot dam across this would impound at the very least fifty or sixty millions of gallons. This would be ample for the present population of 20,000, which at the present rate of increase should double in 20 years. When this occurred the supply could be made effective for probably another ten years by merely adding a few feet to the top of the dam. The reservoir would be about 330 feet above Invercargill, a height sufficient to give nearly double the present pressure of the present supply. The proposed pipe line would follow the line of the formed road, traversing in all about 25 miles of country. In two or three cases, where it would be necessary to make a detour to avoid hills on the road, the pipe line would have to go across private property, but this should not present any difficulty, as owing to the wide powers possessed by the Council under the Public Works Act, property owners generally find it advisable to come to an amicable agreement. Besides the gentle nature of the fall, the country Is peculiarly well adapted for a pipe line, as is is not subject to either earthquakes or floods. Mr Fox was not willing to say much concerning the cost of the scheme, as he will shortly be putting a comprehensive report on the whole matter before the Council. He remarked, however, that even if the cost were £100,090, the interest on the amount would amount to not less than £lOOO a year under the cost of the present pumping system. THE PRESENT SYSTEM. It is interesting to note that the present system of pumping water from artesian wells was started in ISB6, the plant being installed by Mr William Sharpe, who was then Town Engineer. Since then the system has been considerably altered and improved. The cost of operating and maintaining the plant has proved considerably greater than was at first anticipated. In 1911, when a poll was taken as to the advisability of going ahead with the Dunsdale scheme it was estimated that from 1921 to 1926 the cost of operating and maintaining the present system would be £3650 a year. The actual cost was about double this. In the last balance sheet, published two years ago, the total cost was given as £1,900, made up roughly as follows: — Fuel £1,500 Electric Power £3,340 Wages £1,500 Since that time the cost has increased still further. In the event of the Dunsdale scheme being carried into operation it has been suggested that this plant could be retained as an emergency one in the event of a break down on the main pipe line.