WATER SUPPLY FOR SHANNON.

Shannon News, 24 February 1922, Page 3

WATER SUPPLY FOR SHANNON.

SCHEMES BEFORE THE COUNCIL, MR R. EDWARDS’ PROPOSALS. A proposal for providing Shannon with an up-to-date high-pressure water supply has been contemplated by the Borough Council for some time, and the borough engineer (Mr R. Edwards) has advanced matters so far that he .was able to lay the preliminary outlines before the Council meeting on Tuesday evening. The Mayor presided, and there was a full Council present. 6 THE ENGINEERS’ REPORT. Mr Edwards, commenced by submitting a report covering the steps he had taken to date, which was as follows:

“In accordance with your instructions, I have commenced the preparation of a scheme to supply the inhabitants of Shannon with an adequate supply of pure water for do- j mestic and all usual purposes; and j which necessarily must provide for immediate necessity, and for a rea- j sonable increase of the population oi Shannon in the future. It would be * superfluous to go into the question of rainfall or fluctuation thereof for obvious reasons. The catchment area of the Mangaore stream and its tri- , butaries comprise a very large area j of the Tararua Range of mountains The immediate watershed is mostly J forest and partly sheep country, lhe , minimum, summer flow at the railway , bridge is 2450 cubic feet per minute, and either the Mangatangi branch or the main branch running about, parallel fop some distance with the Mangaore track will provide an ample supply of good water for Shannon. The minimum requirements for a -population of 1000 would be 100,000 gallons per diem. I shall treat the subject of the quantity of water to be supplied more fully in a subsequent report, While 1 oil this question it is as well/ to note the relation of supply per cajpita to total population. In large cities there is generally a greater ~average daily' consumption per capita, reaching as much as' 100 gallons.' A safe basis for a population of, say, 10,000, will be 35 to 45 gallons per capita, diem ex die. “I .have made a careful survey of the surface from, peg 0 at the comer j of Thompson and Bryce Streets to ; the junction of East? Road and Clapham Street, peg No.- 29, and from this later point along the Shannon Ecjst Road to a point at water level jn the Mangaore stream, at the N.l. end of the proposed power house of the Public Works Department, a 1 total distance ol' 263 chains .12.5 links as per plan. A glan«e at the longitudinal section of the surface levels will show at once that- a portion cl the borough is 20ft above the line ol ..virtual declivity, and it a pipe was laid along the road at this level above the hydraulic inclination it would not give satisfactory! results. The reason, shortly, is that the pressure at this ' point in the pipe' where the water is flowing becomes less than that ol the atmosphere. In jeonsequenee the tar accumulates in the highest point of the pipe so as fo obstruct the flow oi wafer. I have, hpweyer, taken trial j levels for a pipe track through sec- j tions 693, 692, 546, 569, 570 , 572 and 1 573 to either Grand or Vogel Streets. _ Along this route I have secured a. fall- j ing grade: in Grand Str.ee.i, for a lew chains, the pipes would -require to be sunk about six feet below .the surface, 1 then we secure a perfect grade to the centre of the borough, where die | greater amount of water will be used. ; The levels of the surface along the Shannon East Road also disclose trie j fact that the pipe, if "laid along the road from peg 29 to the power-house . site W.L., would also be a consider- 1 able distance above' the hydraulic in- : clination. I have, however, made an examination: of the surface between , the road and the stream, and find j that, if the Mangahao waste water is ; decided upon, at a point 190.85. >eet | above peg 0 (Thompson and Bryce j Streets), a, correct. Hydraulic pipe j track can ~be secured by making a ; slight detour to the north of the road- j line. If, however, a .greater head is , subsequently) adopted, the pipe track j can be kept to the road surface for j the greater part of the- distance. Re- j ference is made to this question later : on in the report.

“As to the question of the quality of the water after (having passed through the I feel satisfied there .will be no •objection to its quality; in' fact, it will fie the best quality of water available', owing to the nature of its souirce, the Manga.- • hao River fieing led chiefly by the snow caps of the Tar nr u a Mountains. Although the head of 160.85 -feet wifi be sufficient, I may point out .that the greater the head the less will he the cost of the pipe track, for obvious reasons; secondly ,a greater amount of | water will go through the pipe. R ( may also be well to consider the possibility of an increase for the future. It will be possible to use as a power j electricity, if, ion Instance, another 60ft of head was added to the 190.85,

increasing the This increase wojim so alter the hydraulic inclination so that the pipetrack could he kept on the public road nearly all the way; also the amount, of water would be greatly increased. This scheme would require a small reservoir, capable of holding, say,* 200,000 gallons, into which the water would be pumped by electrical power. At present I cannot obtain any reliable information as to the cost of power, but assuming it would be id per unit, the annual cost would be just under £SO. The pumping of water in this case would lend itself to low charges, as the pumping can be done after 11 p.m. up to, say, 5 a.m. This is the period in the 24 hours when the load is very low on the electrical producing plant.

“There is another scheme that I feel I should at this time lay before the Council. The Public Works Department has installed a temporary water supply from the Mangatangi branch of the Mangaore stream, which is delivering water through a lOin black iron pipe to the present steam plant. An intake has been established in the stream, ,451't (measurements by the Public Works Department) above the steam engine site on the roadside. The pipe track crosses the Mangaore stream twice —at the lower end on a suspension bridge. This supply will be taken up as soon as the Mangahao work has been completed, and it may he worth while considering the acquisition of this plant.

“Before ueciding on a selection of any of me three suggested schemes to supply Shannon with water, with the approval of your Council, I shall make a cereful inspection of the south branch ot the Mangaore stream. As far as my present examination ha# gone, I am inclined to ttyink that securing a pipe in the gorges would be very costly. A further examination by means of levels from the Shannon East Road along the Mangaore track may disclose the fact that a pipe track could be secured practically along the road. If so, and the length of pipe is not too great, the greater head (pressure) may make it possible to reduce the size of the service main, and the cost thereof more than sufficient to compensate the extra cost owing to the increased length which 1 estimate roughly at, say, one mile.”

RETICULATION AND OTHER

MATTERS. Mr Edwards relerred to reticulation and said he did not beiieve in risking big sums of money in heavy pipes to provide lor requirements 20 years ahead. He suggested cutting down the main pipe to 4 or 5 inches in Grey Street, and then reduce the sizes lrom that. One or two of the main streets should be used as distributing centres, and from there to other streets the pipes would be reduced to meet requirements. The Mayor asked how much further it would he necessary to -go to reach the south branch of the Mangaore, mentioned as the source of one of the proposals, than to take the water from the stream at the site of the power-house, also a possible source of supply. Mr Edwards: About one mile.

Cr. Gardner inquired if it would not be a shorter route to bring the pipe-line across country to certain places instead ol' following the road, and thus get a more direct route.

Mr Edwards said that would be possible in places, but it would be necessary to follow the general contour of the country.

Cr. Spencer: How will the pipes be protected if brought through private property if not laid underground?

’ Mr Edwards said the line would be underground except across creeks. Cr. Fargher mentioned that there Wias' a good demand for water by settilen outside the borough. Mr Edwards stated there would be no difficulty in disposing of large quantities of water in that way. Cr. Fargher: .How is it disposed ol? The Mayor; By tribute, the same rs is done in Levin.

The Mayor pointed out that water was urgently wanted in Shannon, and whatever proposal was adopted it must, be pushed ahead so that the scheme can be brought, to fruition at the earliest possible date. £lv. Spencer considered that it would be a wise policy to go steadily and make the fullest inquiries. Mr Edwards said that was correct, although, if necessary, he could go on at once with the scheme in the Mangaore stream at the works. Cr. Fargher considered Mr Edwards should be complimented on the amount of work and thought he had put into the report. The Mayor agreed, and added that as soon as Mr Edwards laid the best, scheme before them, the borough would raise the money and go on with the proposal. A vote of thanks to Mr Edwards for his report was carried unanimously, the engineer stating that he would endeavour to submit another report to the next meeting.