WATER SUPPLY

Wanganui Chronicle, Volume 83, Issue 55, 7 March 1939, Page 10

WATER SUPPLY

LOWER RANGITIKEI DISTRICT ENGINEER SUBMITS SCHEME The Rangitikei County Council, on Friday last, considered comprehensive alternative schemes for reticulating with a water supply for the lower Rangitikei district. The schemes submitted by Mr. S. A. R. Mair, engineer, were as follows: — Proposal No. 1. Rangitikei River at Houhou. I Proposed source—Rangitikei River, at Houhou, near Rata. Water would be pumped into a reservoir either concrete or earth dam near the road on Log Whare Flat on Messrs. Meads’ property. The reservoir would be 850 feet above datum and the intake approximately 305 feet. From the water would gravitate "ver the whole of the area shown on plan No. 1 and could also gravitate as far up and down the coastal belt as may be | required. i To ensure ample clear water being 1 available at the intake, a pond would Ibe excavated by dredge below ordin- | ary water level on the loam-covered I shingle river flat, and located to ensure natural filtration and purification | and immunity from floods. I The high lift pump proposed would ibe three separate units electrically | driven and automatically controlled by the rise and fall of water in the reservoir. Each unit would be capable of lifting 600 gallons per minute, and the three would be capable of pumping the full daily requirements in 10 hours to make available the cheap electricity night rate of id per unit. The reservoir proposed, if in concrete, would hold a full 24 hours maximum consumption, and if .an earth dam, several days’ consumption. Proposal No. 2. Mangara Stream, at Galpin’s. The Mangara Stream is fed by the run-off of an area of approximately 8000 acres of grazing land lying to the west of Mt. Curl. It is also fed by several springs and lakelets, and is i apparently a strong stream of appatirently reasonably pure water. There is at present only the occupied house I within the catchment area. I At no time since the water supply I proposal has been under investigation has the stream been at its minimum flow, but careful measurements made at the middle of last April gave a minimum flow of 600,000 gallons per day of 24 hours. The intake is 310 feet above datum or 150 feet below Marton Rail- | way Station, and to enable water to gravitate over the proposed area, jt would require to be lifted about 650 feet to a reservoir on the watershed near “Woodlands” homestead. Apparently a safe estimate of he minimum flow of the Mangara would be 500,000 gallons per 24 hours, but 210 feet above is Galpin’s Lake in which, with a small expenditure, might be stored one hundred million gallons, or three months’ total consumption. Possibly with this storage on hand at the commencement of the summer • and augmented by a daily supply of half a million gallons from the stream 1 flow in the summer, this source might provide sufficient water for a ‘ satisfactory supply. To verify this, a I careful and complete investigation • would require to be made during the I driest part of the summer. : Assuming sufficient water is available, the intake pumps on the Manj gara would have a lift of 250 feet into • Galpin’s lake. From here it would be ’ again pumped to reservoirs similar toto scheme No. 1 near “Woodlands,” a height of approximately 400 feet. From the reservoirs it would gravitate over the whole coastal belt, but break-pressure valves would be required for lower levels. As the service main would pass fairly close to Marton Borough Council’s reservoir, this could be replenished from time to time, if desired, and sufficient water was available. Proposal No. 3, Rangitikei River at Pourewa It is proposed to take water in a similar manner as at Houhou, but near the confluence of Pourewa Stream with the Rangitikei River. The pumps would be at 240 feet above datum and water lifted to a concrete reservoir on Mt. View at 620 feet above datum or a lift of 380 feet. - This reservoir would hold 1,000,000 gallons, from which water would i gravitate over some 40,000 acres of the lower levels, leaving some 15,000 > acres elevated to be supplied by furthr pumping. To serve this latter area, I propose ■ to gravitate from Mt. View reservoir to pumps at Upper Tutaenui below « Somersal Road at about 550 feet i above datum and pump to a second- ■ ary reservoir near Galpin’s Road op- . posite the Marton Borough Council’s reservoir at 800 feet above datum. From this reservoir the higher - levels of the district could be served by gravitation, including the area of ; Fern Flats to Turakina. Regarding sources of supply, I am definitely satisfied with No.’s 1 and 3, : but No. 2 requires further investiga- • tion regarding minimum summer flow . of the Mangara Stream, storage ? capacity of Galpin’s lake and a care- . ful survey of work to raise this capacity. After careful consideration I havebased the pumping on a constant daily supply as 300,000 gallons per day, for 365 days and 700,U00 gallons per day for stock for extra 200 days. This gives the annual amount to be pumped, as; — Three hundred thousand gallons by 365 days. equals 109,500,000 gallons, ■ and 700,000 gallons by 200 days equals - 140,000,000 gallons, total, 249,500,000, ■ or say 250,000,000 gallons per annum. Assuming the complete scheme to , cost £150,000 and interest at 3i pei . cent., sinking fund li per cent., maintenance, etc., 1 per cent., total 6 per cent., the approximate annual charges would be: — , £150,000 at 6 per cent £9,000 Pumping charges . £1,750 £10,750 This would make the cost of the | assumed annual consumption of 250,-

000,000 million gallons 10.3 d per 1000 gallons. The meeting, without committing the council, passed a hearty vote of thanks to Mr. Mair, who drew up the report, and resolved that an analysis of the Rangitikei River water be obtained and if satisfactory to approach the Government with a view to its approval and assistance towards one or the other of the schemes, each of which is to cost about £160,000. If Government approval and offer of subsidy if forthcoming, the next step will be to call a meeting of the county ratepayers concerned. Should the scheme be approved by that meeting a poll of ratepayers in the proposed reticulation area would be required.