FAIRLIE WATER SUPPLY

Timaru Herald, Volume CXLIV, Issue 21053, 3 June 1938, Page 3

FAIRLIE WATER SUPPLY

Best Source at Three Springs LOW ANNUAL CHARGES WORK FOR 50 MEN Important facts in a full report prepared on the Fairlie water supply and sewerage scheme by the consulting engineer, Mr H. G. Royds, are that the best source of supply is undoubtedly Three Springs, that the annual charge would only be £2OO a year more than is at present being paid for sanitation and water races, and that employment would be provided for at least 50 men for 30 weeks. The report has been prepared for presentation to the a monthly meeting of the Mackenzie County Council to-day. “The best supply is undoubtedly Three Springs,” the report states. Attempts to find an underground supply had been unsuccessful; one shaft had been put down more than 50 feet and another about 27 feet. Both had been in positions where available evidence and water diviners indicated that there should be water. The attempts were abandoned, and attention was directed to the present water race. Estimates had been prepared for filtering, chlorinating and pumping to a reservoir south of the show grounds. The Health Department had finally reported against the use of the water. In addition, it was understood that there was a good deal of popular prejudice against the use of the race. Three Springs would supply one of the best sources of supply known in New Zealand. Three Springs water had been analysed by the Public Works Department as a possible source for the downlands supply, and it had been found to be of excellent quality as well as being very soft. It was free from contamination, did not become muddy or discoloured in times of flood and its quantity was constant at nine cusecs. Under the circumstances, the Three Springs supply, piped to Fairlie. had been adopted as the most satisfactory proposal. Quantity of Water Required In dealing with the quantity of water required, the report assumes that in addition to supplying the town of Fairlie. sufficient water should be provided to supply the Eversley settlement. Kimbell. and the houses near the route of the pipe line along the main road. The population of Fairlie is put at 700 and the outside population at 160. and the supply has been designed for a 50 per cent increase in population, or for 1300 people; on the basts of 50 gallons a head a day, the average demand for water would not exceed 45 gallons a minute, and the maximum demand would be 135 gallons a minute. The question of fire protection had been considered. Good authorities recommended two fire streams of about 200 gallons a minute each for a town of 1000 people, but owing to the long supply main, that standard would be too costly in the case of Fairlie. One fire stream of 250 gallons a minute (or two small streams) had been allowed. Il would be obvious that the size of the supply main would not be governed by domestic demand but by fire fighting needs. The distance from Three Springs to the centre of Fairlie was 61 miles, and the total fall in that distance was 368 feet. A relatively small pipe delivering a constant flow to a service reservoir at a point 150 feet above the town was recommended. The main would be designed to give only sufficient pressure for domestic supply for the houses along its route, and at the same lime to deliver about 45 gallons a minute to the service reservoir. The overflow from the pipe would be con trolled by a float valve. Capacity of Service Reservoir The service reservoir would hold about 30,000 gallons, which, coupled with the constant flow of 45 gallons a minute, would give an emergency supply to the town of 250 gallons a minute for more than two hours. To provide for a maximum demand, and especially for fire fighting purposes, the pipe from the reservoir to the town would have to be much larger than the one above the reservoir, and an eight-inch pipe, which gave a reasonable loss of head when delivering 250 gallons a minute, was proposed. The length and therefore the cost of the lower main was governed by the pressure required at Fairlie. The scheme as designed would • provide 661 b per square inch static pressure, or about 501 b to the square inch at times of maximum draw-off. That was not a high pressure, but it was considered sufficient for fire fighting needs, especially as it was not likely that there would be tall buildings in Fairlie. Most of the pipes would be laid 15 feet from the street boundaries, and 2ft 6in below the ground surface. They would be of sufficient size to provide an efficient fire-fighting service in all parts of the town. Fire plugs would be 200 feet apart in closely populated and business areas, and 300 feet apart where houses are scattered. Service pipes to property boundaries are included in the estimates, it being usual to include that work in loan expenditure. About 12 miles of piping would be involved in the scheme, and it was evident that the cost would depend largely on the type of pipe used. The estimates were based on the use of asbestos cement pipes, which were the cheapest at the present time, for small sizes. Final proposals would require competitive tenders. Asbestos cement pipes had many features to recommend them, and had already been used largely in New Zealand, the largest user probably being the Auckland City Council. There would shortly be two sources of supply in New Zealand lor the pipes.

Sewerage Scheme •*’* may be said that the configurat.of the ground at Fairlie is almost ideal for sewerage,” the report states with reference to that part of the scheme. Self-cleansing gradients can be obtained in all sewers, except for one short length near the library, and at that point I have provided for an automatic flushing tank.” Provision had been made for earthenware pipes bedded and haunched in concrete. Wherever possible, sewers would be laid at the back of houses. In small towns, that system presented many advantages over the usual system of laying sewers in streets. There was little difference between the estimates for the cost of a convential septic tank and an Inhoff tank, and as the septic tank generally used in New Zealand was out of date overseas, he would recommend that the Inhoff tank, which had several technical advantages, should be adopted for Fairlie. The effluent from the tank would percolate through field pipes into the gravel of the old riverbed, and would ultimately find its way to the river. No nuisance would be caused by the effluent at the place of discharge or to water users lower down the river. Cost of Scheme After the unemployment subsidy is deducted, the cost of the scheme is put down at £17,000. The total cost would be in the vicinity of £21,000, made up of the following estimates:— £ Main water supply from Three Springs 6660 Fairlie reticulation 4980 Sewerage 8080 Clerk of works 225 Engineering at £7/10,'- a week.. 1047 Total cost of scheme .. .. £20.992 The estimate of labour costs is made up as follows: Main water supply £l2OO. water reticulation £lOOO, sewerage £4600, making a total of £6BOO. In those estimates, a fair contingency was included for rising labour costs. As far as the unemployment subsidy is concerned. Mr Royds states that he had experience with regard to that matter in connection with the Methven scheme. The total cost of the work had been £9OOO, and the subsidy could have been £lBOO. On the Fairlie scheme, at least 50 men would be employed for 30 weeks, and assuming 40 unemployed men were engaged, the subsidy at £2/10/- a week would be £3OOO. at £3 a week £3600, and at £4 a week £4BOO. “Your Council no doubt already has some idea what rate of subsidy could be expected. I have heard of one case recently where £4 a week has definitely been offered,” Mr Royds adds. “I will not go closely into financial considerations, as I understand your engineer-clerk (Mr D. Jeune) will prepare a report on that aspect. I understand, however, that the present cost of nightsoil disposal and the maintenance of street water races, which take away bath and sink waler, is £641 per annum. Assuming a loan of say £17.000 with interest and sinking fund totalling five per cent, the annual capital charge would only be £B5O, or £2OO a year more than you arc al present paying. No increase in your staff would be needed to maintain either the water supply or sewerage. it is evident that for a small increased annual cost, Fairlie can be provided with modern water supply and sewerage facilities to replace the present inconvenient and insanitary arrangements.”