GORE WATER SUPPLY

Southland Times, Issue 22510, 19 February 1935, Page 4

GORE WATER SUPPLY

ENGINEER’S REPORT.

SCHEME FOR SUBSIDIARY SUPPLY.

An interesting report on the proposed supplementary water supply scheme for the borough of Gore pending a decision to adopt an adequate permanent scheme was submitted to the Borough Council last evening by the engineer (Mr E. G. Wilson). The report was the outcome of a decision of the council to investigate the possibilities of securing a supplementary supply, and the engineer discussed the merits of a gravitation scheme compared with a pumping system and touched on the possibilities of securing artesian water. The report was as follows: . An important point to be considered is whether the Health Department will be prepared to allow the water to be used without chlorination or not. This can only be ascertained after' an analysis of the water from the well has been made. If chlorination is insisted upon, then the area from which a supplementary supply can be 1 drawn will be restricted to the proximity of the present pumping station. The most suitable site in this case would be at the intersection of Oldham and Gorton streets in the corner of the Caledonian Ground. If a well were put down there, it could be controlled by the pump attendant with little difficulty. The water-bearing strata in this locality is a loose alluvial deposit lying on an under rock structure, the dip and direction of which is south-east. The feeding source of the well would thus be from the north-west. A certain amount of water that may normally come to the new well would be intercepted by the drawing power of the existing main well, but I do not think this would be sufficient to impoverish the new well to any great extent. Another site that has been mentioned is section 8, block 17, in Avon street. This would only be available provided chlorination were not required. As this site is situated close to a thickly settled area with considerable danger of sewerage contamination, I think it quite improbable that the Health Department would approve of it, and I have not considered it necessary to investigate it. I think the whole issue revolves around the policy to be adopted by the council in providing a supply for the town during many years to come. If a gravitation supply is likely to be provided within a few years, a supplementary pumping supply need only be looked on as a temporary measure. If the proposal to provide a gravitation supply is to be abandoned and pumping adopted permanently as a standard for the town supply, then something better than a temporary subsidiary supply can be adopted. Personally I believe that no mechanical system of handling water can ever compare in any one respect with the natural process of handling by gravitation. The initial cost may be much higher, but the wear and tear on tire machinery, and the constant incrustation and eventual renewal of mains, sooner or later throws every mechanical system out of court. However, if mechanical handling must be continued at Gore, the best method would be to set aside a certain section of the town and to provide it with a separate pumping unit. A great relief would then be given to the present pumping unit. The most suitable area for this would be West Gore, and if considered advisable, Devon, William and, say, Albany streets could be included. A suitable site for a well and pumping plant could be obtained and a small service reservoir provided capable of holding 100,000 gallons. It would be unlikely that chlorination would be required for this area, as the whole of the sewerage system in West Gore was constructed to a much higher standard than in the rest of the town. In addition tire mains are in a much cleaner state than in the rest of the town. Many of the older mains are seriously encrusted, and the fractional resistance is very great. This is the main cause of the low efficiency of the pumps. A separate pumping unit would eliminate much long distance pumping and frictional resistance. In addition the larger part of West Gore lies from 10 to 15 feet above the level of the present pumping plant. This lift, equivalent to from 4Jlb to 6Jlb per square inch internal pressure, could be eliminated from the pumps. As this is only a suggestion at the present stage, I have not elaborated it or given an estimate of the cost, but I will supply this if the proposal is likely to be considered. It has been suggested that deep boring may reveal a very adequate source of supply. It is always possible that something of the kind may be struck, but it is not very probable. The rock structure lying underneath the alluvial deposit belongs to a very old series of the earth’s crust, and in addition it is severely canted from the horizontal. Any boring operations would have to penetrate several layers lying at an angle, and it would be a matter of luck if a strata were struck carrying any appreciable quantity of water. The term “artesian” has been loosely used, but it is unlikely that any artesian water would be located except at extreme depth. The geological conditions for an artesian supply are quite different from those underlying Gore and the vicinity. A point of supreme importance is the greatly increased cost of lifting from a depth of, say, 250 feet compared with 25 feet. Divining for an underground stream has also been suggested, but I recommend that no action of this sort be taken, as in all its forms it is a system of pure quackery and will not stand the slightest scientific test. The Water Committee reported that it had decided to submit the report to the council with the recommendation that as a temporary measure, the engineer be instructed to carry out a scheme on block A at his estimated cosh The matter of bringing in a gravttation supply had been left for the council to consider. The recommendation of the Works Committee was adopted.