WATER SCHEMES

Gisborne Herald, Volume LXVI, Issue 20101, 22 November 1939, Page 4

WATER SCHEMES

NEW CALCULATIONS WAINGAKE V. WAIPAOA MR. N. H. BULL’S CLAIMS ANALYSIS OF REPORTS A claim that in the calculations of comparative costs of gravitation and filtration schemes for Gisborne’s wafer supply certain .important factors had been overlooked, and that as a result of this oversight the comparison appeared to favour filtration unduly, was advanced at a meeting of citizens held iast evening. The meeting appointed a committee to check the figures presented by the principal speaker, Mi. N. 11. Bull, and to investigate the arguments lie advanced, with a view to calling a. further meeting and acquainting the public of its findings. Having, while a member of the Gisborne Borough Council, criticised the proposals for establishing a filtration plant at the Waipaoa River, and having contended that on the basis ol' the consulting engineer’s report it would be cheaper to supply a population of 20,000 people by a gravitation scheme from Waingake than by filtration, Mr. Bull was asked to address the meeting and enlarge upon his earlier statements. After reviewing the position as he saw it, he pointed out that it was clear from the Vickerman report that the needs of 20,000 people could be supplied either by gravitation or by filtration. Consulting Engineer’s Report He dealt with the merits and demerits of both schemes, and contended that one of the main considerations influencing the Borough Council in installing an experimental filtration plant at the Waipaoa River was the calculation contained in the Vickerman report that the cost of water derived from this source, by means of pumps and filters, would be sjd per 1000 gallons per annum, as against 7d per 1000 gallons per annum involved in developing the gravitation scheme from Waingake, including the erection of a 60,000,000 gallons impounding dam at a cost of £40,000, and duplicating 11J miles of the existing pipeline. The speaker claimed that an essential item in the cost of the filtration scheme had been overlooked in computing the figure of 5.1 d per 1000 gallons. He further stated that the averages on which the consulting engineer had arrived at his comparative costs did not clearly place the full facts before the public. Mr. Bull said that to obtain a true conception of the costs of both schemes, as reported upon, it was necessary to deal with the costs as disclosed in the report for a supply of water up to 500,000,000 gallons per annum, which volume the consulting engineer considered would reasonably meet the needs of a population of 20,000. He discussed the figures in detail, and claimed that it was evident from the report that the filtration scheme would cost approximately per 1000 gallons per annum, whereas the cost of a gravitation scheme such as the report suggested would be 7d per 1000 gallons. Claim for Gravitation Scheme If his contention was correct, then from the figures given in the report, with the adjustments which he claimed should be made, it would cost £12,300. approximately, to supply 500,000,000 gallons by the gravitation scheme from Waingake, and approximately £16,900 to obtain the same supply from the Waipaoa River. Further, while the present pipeline was used without duplication, the saving in favour of the gravitation scheme would be about £7500 per annum, as compared with the cost of the filtration project. 'Mr. Bull referred to the urgent need of obtaining additional water to meet drought shortages, and pointed out that the consulting engineer admitted the possibility of meeting these shortages, so far as a population of 20,000 people was concerned, by expanding the gravitation scheme to include the impounding dam and the duplication of the pipeline. The speaker also pointed to the continuing costs of filtration, which, he said, would go on for ever once the old pipeline was discarded. In the case of the gravitation scheme, the provision of sinking funds could wipe out the initial outlay in, say, 33 years, .and posterity would enjoy the free use of the pipeline facilities for the remaining lifetime of the pipes, which could be safely estimated at from 50 to 60 years, and might well be much more. Heavy Capital Sum Mr. Bull also referred to the cost ol pumping and treating water from the Waipaoa River, which the consulting engineer had estimated at 2\d per 1000 gallons per annum. This would mean an annual cost ol £6844, to deliver 2,000,000 gallons per day to the public. Capitalised at 4 per cent, this was equivalent to a sum of £172,000. The amount would more than counterbalance the capital charges on a new pipeline if and when that became necessary. Moreover, once the impounding dam and pipeline duplication has been provided for, the costs to the borough would remain practically static, whereas the cost ol pumping and treating water from the Waipaoa River would rise in an increasing ratio with the rise in the requirements of the public. He produced figures which lie claimed to show that once the impounding dam was erected, 500,000,000 gallons per annum would cost no more than 365.000,000 gallons, on the gravitation principle; whereas with tin filtration scheme assuming the cost to be £14,000 per annum for 365,000,000 gallons, it would rise to £17,000 per annum for 500,000,000 gallons, and over £21,000 to deliver 750.000,000 gallons. Mr. 'Bull said that he made these calculations on the basis of the figures used in the consulting engineer’s report, though he had made certain adjustments which he claimed must be made. The meeting, which was presided over by Mr. Archie Kirk in the absence of Mi;. J. J. Macdonald, convener of the gathering, gave Mr. Bull an attentive hearing, and later appointed a committee to investigate his calculations, with a view to placing further information before tire public.