PETONE'S DIFFICULTIES

Evening Post, Volume CIV, Issue 22, 26 July 1927, Page 11

PETONE'S DIFFICULTIES

THREE SOURCES POSSIBLE

AKATARAWA FOR THE

FUTURE

Last night Mr. H. Vickerman was present at tho Petone Borough Council meeting, when the following report on the Petone water supply by Messrs. Vickerman and Lancaster was considered:— The matters brought under our notice for investigation, stated the report, were broadly the need for (a) increased supply and pressure to meet the needs of a growing population; (b) improved supply and pressure for fire-fighting purposes, especially in the side streets; (c) a water supply for the Koro Koro settlement. PRESENT CONDITIONS. At present water is obtained partly by a gravitation supply from the Koro Koro Stream, and partly by .artesian water pumped into the same mains from wells near tho Hutt River. Tho supply is available over the flat, but does not extend up the hills to the Koro Koro settlement. At the Koro Koro intake a dam has been built at an elevation of 220 fcei above the town, and having a capacity of 8,000,000 gallons, drawn from a catchment area of 2000 acres. Nine-inch cast-iron pipes connect the supply with the town reticulation, at a point three and a quarter miles from the dam. i The Wellington Woollen Mills Company has a prior right to 1,000,000 galions per day, at its dam one and a quarter miles below the borough dam, and the borough is obliged to make up any deficiency by allowing an overflow from its dam. The average amount drawn from the borough area by the Woollen Mills is 200,000 gallons, and the average amount available for borough supply is 600,000 gallons per day. The artesian supply comprises seven 3-inch pipe wells capablo of supplying 720,000 gallons per day. Details' of the reticulation system are given and it is pointed out that, owing to an incrustation, the nine-inch main is now hardly equal to a seveninch pipe, and for the same reason the six-inch pipes in the borough, apart from added friction, have now only a four and a half-inch waterway. ] PRESSURE AND CONSUMPTION. When the supply was first installed in 1902, there was at night a hydrostatic pressure ot', 971b per square inch,, but this hns now dropped to not more than Golb. Tho pressure in the day timo us recorded by the meter in tho council chambers is as indicated below:— July. Feb., 102« 1027. Lowest pressure n0!l> 301b Highest pressure 651b 501b Average during tho daytime, 551b 4f.lb At the power-house, observation showed 301b pressure with the pumps stopped, and from 60 to 631b when working. l Rolativo to consumption the following data was obtained from tlio A^enturi meter on the Koro Koro mains:— July, Fob.. io:ti. 102". Miixlinmn consumption (sallons per lionr) J 11,000 iO.TOO Minimum consumption (gallons per hour) 10,000 12,000 Total dally average consumption (gallons) .. 523.000 .'{70,000 Average, consumption hourly (gallons) 13,500 13,500 Tho quantity pumped is not motored but is estimated to be 180,000 gallons per day for the six months including winter, and a greater amount in summer, up to 400,000 gallons per day in February. The total average consumption is 505,000 gallons per day in tlio winter, and 770,000 gallons "per day in the summer, the averages per head being 50 and 77 gallons respectively. In addition to this, for fire-fighting purposes the mains should be capable of delivering at least 1000 gallons per minute without materially decreasing the prossure. Therefore, any new supply should bo capable of delivering 2000 gallons per minute, and at such a pressure that tho lobscs in tho reticulation system will not reduce the pressure to .much, if anything, below liOlb per square inch. SOURCES TOE 3UPPLY. The sources which may lie considered for providing an increased supply are: (a) The Koro Koro Stream; (b) artesian wells, (c) tho Akatarawa River. • Koro Koro Stream.—The dam on this stream would, with its present capacity, be barely capable of meeting the present demand. To satisfy the increased demand it is estimated that the flam would have to bo built some 30ft higher. The existing nine-inch main would be incapablo of meeting the borough requirements of 2000 gallons per minute, and would need to be replaced by an cighteen-inch, or preferably a twenty-inch pipe, and this should extend past the railway station nnd then turn through the heart.of the borough to the pumping station, and from it feeders should branch to supply tho reticulation system. The cost of raising tho dam aiul providing the now main would be approximately £30,----000. The annual expenses for interest, depreciation, and sorvicc would bo 10 per cent., making tho cost of tho water 7d per 1000 gallons for the extra water supplied. To make this comparable with other pumping proposals, tho cose oi! reticulation mains must bo added, wlion the cost of water will become lOd per 1000 gallons. Tho borough ownn only half tho catchment area, and the farms on the remainder not only render tho water liable to impurification, but: also- by clearing off tho bush decrease tho dry weather run-off. Artesian Wells.—An amplo supply could bo obtained from this source, but in order to ■.. -«t the pressure requirements the \\-aUv would have to be pumped. To take advantage of the cheaper rates for cuivrnt used at night, it wor.id be necessary to build a reservoir on the western hillside, which could be connected by a main with tho pumpm.T station and filled at night. The cost of the new artesian systom would bo abc.it £25,000, and the pumped water cwld be provided at o cost of | about 6d per 1000 gallons. • Akatarawa Eivor.—lt appears to bo inovitablo that Petono must oventually becomo party to tho scheme for a goncral water supply from tho Akatarawa, and consequently Petone should not make a largo outlay on works which may bocomo superfluous at a later date. A scheme to use the present supply in conjunction with the Akatarawa would be unworkable owing to tho difference in the respective pressures. . IMPROVEMENTS FOR FIREFIGHTING. The pressure for fire-fighting purposes is inadequate, not only in tho sidestreets, Which are served by encrusted pipes varying in diameter from throv niches down to ono inch, but also in the main stroets served by six-inch pipes. Tho best method of' overcoming the trouble is to provide a system ot arterial reticulation mains, to feed at intervals into tho existing six-inch reticulation mains and thus reduce the loss oe pressuro along them. SUPPLY FOR KORO KORO. Koro Koro will have to bo supplied by pumping, and it will depend on tho j

oxtrnt of the area to be supplied whether the water be pumped from tlu: Kuro Koro reservoir, from the present pumping station, or from the settling tank on the hillside above the mouth of the Koro Koro Stream. In auy case a water supply must be dear per house. In conclusion the report recommendLS "a general extension to the pumping station, economies to be effected by tho use of automatic gear, and an increase of working pressure sufficient to enable the Koro Koro settling tank to be filled at night, thus making available, the lower nightly power rate. For tho future it will be best to iook to the Akatarawa River." QUESTIONS ANSWERED. In reply to questions by councillors, Mr. Vickermcn stated that it would not be advisable to increase the pressure in the pipes by utilising the pumps, because that would mean lessening the flow from the Koro Koro, and increasing the pumping costs. It would not be economical to iscrap completely the present reticulation system. The encrusted four-inch cast iron pipes should be replaced by four-inch steel xiipcs, which did not become encrusted, and which were cheaper. The costs of reticulation mentioned did not include compensation for private property, as it was assumed that the main would be laid entirely ou the borough property. A source of unlimited supply was available to the borough, but it would be a very expensive undertaking.