THE WATERWORKS.

Poverty Bay Herald, Volume XXXIV, Issue 11126, 15 November 1907, Page 2

THE WATERWORKS.

♦ _ HOW THE MAIN PIPE LINE WAS LAID. SOME DETAILS OF THE BIG JOB. "When will the water be on?" is a question that has been on the lips of scores of residents of Gisborno the pastfew weeks, but the conveyance of the cool, refreshing waters of the beautiful Te Arai stream, 21 miles distant m the back-blocks, amidst charming bush-clad ranges, to our sun-scorched town on the fringe of the ocean, has been a task of considerable magnitude. The simple operation of turning on a tap, the knowledge tiiat there is a big line of pipes over 20 miles m length into the country, or even the paying of the water rates at the Council office, gives one no "conception of the almost Herculean work which has been involved. The mere outlay of the main pipe line above, it might be pointed out, averages about £1900 per mile, and it is only the men who have been on the job who have any idea of the amount of solid toil that has been put m to enable our town to take this, its latest progressive step. For the conception of such a service the community owes its gratitude to tlie ability and skill of Mr R. Hay, C.E., of Dunedin, arid the resourcefulness of the "contractors. Under the pilotage of His Worship the Mayor, Mr J. Townley, a party, consisting of Cr Pettie, Mr R. D. B. Robinson, Town Clerk, Mr W. Wykes, who is to be station^, at the headworks, and a Herald representative, left town at an early hour yesterday morning for the purpose of inspecting the works. The drive to Waingake occupied "a little over four hours. Thence the journey was made on Jiorseback jip the bed of the river to . THE HEADWORKS. „ which are situated 23£ miles from . the Post Office, at an^ altitude of 700 feet above sea level. Here the river — a mountain stream — draining an area of 2800 acres of heavy bush country, untouched by the hand of civilisation, courses placidly down a N clean shingle bed, displaying some most enchanting scenery. Tlie absence of mud flate along the creek sides is particularly observable, _ accounted for . by the fact that the watershed, all of which has 'been secured by the Borough, is still m its virgin state, and there is nothing but leaves to come away. The head waters 'of the stream extend towards the sea, 'being only a distance of three or ifour miles across country from Muriwai. The party was at this stage joined by Mr Wilkinson, the inspector of the contract on behalf of the ' Borough, whose intimate knowledge of every detail was greatly appreciated. At the headworks there is no reservoir or storage basin, usually associated with works. The intake into the pipe is obtained from a small but effective dam, thrown across the creek at a site admirably. -suited for the purpose. The gorge narrows here considerably, bounded by a wall of -rock, and is spanned by a wall Of masonry 27ft "m length. The dam, commencing at its base with a width of about 6ft ; , has been sloped with a curve, " denoting much strength, till it reaches 7ft above the bed of the creek, narrowing on its ridge to 2ft. . . Picked, boulders from the creek, carefully squared and pointed, have been utilised m the building, oif- the dam. Yesterday the overflow was pouring gracefully over the wall. A sluice gate at the base allows the basin of the intake to -be nm off for cleaning purposes, an operation necessitated by the leaves. To minimise the necessity for this as much as possible, a couple of stone walls are being thrown across the creek higher up, to catch the debris. Immediately below the dam, and skirting along the base of tlie rocky face,- which abuts on the eastern side. oft the creek, is a solid block of concrete, a chain m length, containing a 12in pipe, the very top of the main. At its upper extremity, rind inside the intake basin, is placed a large square filter, resembling an iron tank, fitted with perforations. Tliis prevents 1 the invasion of rubbish into the pipe. A valve and scouring outlet intervenes between ,the. end of the. 12in pipe and the 9in pipe, which directly follows, and after traversing nearly two miles, empties the water into the break-pressure tank. The construction of this section was an extremely difficult one. The gorge, much confined and contorted by the encroaching hills and the creek, ifalls rapidly over a rough and rocky bottom. Out of this a trench 4ft deep had to be hewn, or rather mostly blasted by gelignite. The task was no mean one. Bedrock had to be found, with an even graduation. Frequently a solid mass of stone blocked the way, and. a day's blasting operations were necessary before a single pipe could be laid. Other than that, the line follows down stream, crossing and re-crossing and taking advantage of any adjacent and substantial piece of flat bank. The principal engineering difficulty was the negotiation of what is known as the peninsula, whereon is the Borough whare, or cottage, for the official m charge of the Headworks. To negotiate the isthmus, rather than follow the river, necessitated a sudden drop of 30ft, which had to be provided for by special castings. It was at first proposed to tunnel tlirough tlie isthmus, but seeing that it was a solid wall of papa rock, the present alternative Avas agreed upon. This job is very substantial, and no trouble whatever is anticipated. WHAT THE BREAK-PRESSURE TANK IS FOR. . The next object of interest is the break-pressure tank, a concrete cistern partly sunk into the ground, and situated on a nice little river-bend clearing. The tank measures about 12ft x 10ft, and is "built of solid concrete. It is a most interesting feature of the scheme. Briefly, tlie intake of the service is situated at an altitude of 700 ft above sea level, and the velocity obtained by taking the water from his height would be far too. great were it coupled up directly with town. To obviate this, the pressure has to be "broken," consequently a "tank" has been employed. From the headworks to the pressure tank, it will be remembered, the main is only a 9in pipe, which, singular as it at first appears, fills, and far] Aore than fills, the 15in pipe that spans! the distance thence to town. The explanation is that from the .intake to the j tank, . a distance of 1-$ - miles, tiie creek | falls rapidly, m fact it falls m that short span nearly the same height as from thence on to town (Lytton • road, 19£ miles), f or tlie pressure tank is at an altitude of 405 feet above sea level. Tlie velocity on tliis upper section is consequently very great ' compared with the long graduated section below. Pouring, m witli considerable force at one end of the tanki. the water finds its way through a perforated nozzle into the pipe line for town, and the excessive volume of the supply rises up m the tank and finds exit through the two large side washes at the top. The constant turmoil of the water also causes any leaves and debris which may have found its way into the pipe at the intake to come to the surface, and to. be carried of by the overflow. When m full working capacity, the surplus water from the tank is considerable, and quite fills the 9in escapement pipe to the river. Besides a main valve a sluicing valve is also provided at this- point for scouring-out purposes. With such an excessive pressure available, it may be asked why the headworks were extended so high up fit-ream, but the explanation is that it was deemed advisable to proceed beyond the junction of a stream which flows off Mr H. G. Smith's property, for the reason that the latter, being denuded of its bush, the water off that watershed, aftei heavy rains, is much discolored. It was also prudent to avoid questions of ripa-! rian rights. An indication of what would be available from the ,700 ft altitude was gamed last week, when, with tlie pressure tank having been cut out, and the link spanned by a temporary 3in connection, the big valves of the pipe line all closed down and served by 3in bye-passes, a pressure of no less than 2751bs registered at Te Hapara. A VALUABLE AUXILIARY. A few chain below one- readies the auxiliary intake, a most valuable provision m case of anything happening at the intake, or should the latter be closed down for repairs or cleaning. Into a basin formed by a boulder bank, yet to be constructed, extends a 9in pipe, which a couple of chains further on connects with the main line. The working of this auxiliary supply will be quite automatic. Although the pipe end, protected by a nozzle, may be left open, the balance of power is so adjusted that not a single drop of water will flow into the main

HaCH_MMHH_______a______________H_MM_______________nMßßMHHmMHM pipe line unles6 the pressure on tlie latter at the intake or pressure tank is reduced below its ordinary working pressure. When that takes place the pressure will be automatically made up by tlie inflow at the auxiliary. More scour-ing-out provision is afforded here, since the auxiliary may also be used for the purpose of cleaning the pipe between it and the pressure tank, a few chains above. The utility of this auxiliary may be better illustrated by the fact that whilst the main pipe line, if it were shut down at the headworks for repairs, etc., would hold sufficient for two days' sup- | ply of the town, the pressure would be materially affected unless the auxiliary were available, and for fire extinguishing purposes the provision m such an instance is invaluable. . PIPE-LAYING IN THE RIVER. In the first 3± miles, traversing what is called the gorge, the pipe line crosses and re-crosses the river no less than 56 times. Skill and perseverance were important factors. After about £100 had been spent by the Borough Council m opening up a rough track to give access, the contractors had to expend between £300 and £400 m road construction to haul their pipes and materials conveyed to the respective places along the line. Owing to the asphalt and hessian coating on tiie pipes, much care had to be taken, and they were conveyed on a single axle lorry/ fitted with a front guiding wheel. Transportation was a serious item of the contract. The main camp was located at the peninsula, near the Borough whare, which is a fairly comfortable two-roomed cottage, standing "on a commanding " rise. It was erected at a cost of about £110, and the timber had all to be packed on horses on the, rough track. About 60 men were encamped at. this spot. at various times whilst the pipe-laying m the river was m progress, and to-day the frameworks of numerous tents, whares, and cook-houses remain ' reminding one of the scene of life and activity of last summer. Commencing on the preliminaries m June, 1906, it was January last before the pipe-laying gang (after four months' hard work) got out of the gorge". Slips have been rigorously avoided, and where they have .been traversed the pipes have been placed at a perpendicular angle but m most cases it was preferred to hew out a channel m the river bed. In all these latter places the'pipe is covered by a layer of 9 inches of concrete, covered over with a couple of feet of boulders to the level of tlie. surf ace to keep them • free from injury. At some of the river crossings, however, the result of a very severe winter- upon a iiewly-constructed work was m some places to cause an erosion on the protective work. Tliis, however, will all be rectified, and protected, m some places, •by stone wiers formed with i wire netting. The operation of spanning the river, rendered necessary the divergence of the water for the time being, and tliis was ingeniously arranged by utilising a lengthy fluming of 80ft, which carried of 4 all the water whilst the pipe-laying operations were successfully proceeded with below. CURIOUS MAORI DIFFICULTY. . .Proceeding down stream from the headworks, which are a quarter of a mile within the Borough propertyj all the land on the right is Native-owned, whilst that on the left has recently been taken up from the Orown by. Messrs H. G. Smith, G. Osborne, J. McMichael, and Shanks Bros. When approaching Wilson's woolshed, at the bottom of the gorge, and a quarter of a mile ifrom the Manuthke store, ' a, . deviation was proposed across the Native land, which would liave meant the tunnelling of .a, saddle of a hill and tlie traversing of a nice stretch of flat. Unexpectedly the Natives objected stoutly ; the land was tapu. The contractors, therefore, had no option, but to continue along the course of the river, adding several chains to the length of the pipe, and necessitating a bend at an acute angle. At this point the Te Arai stream, [from whence the supply is drawn, junctions with the Titokonui stream, from whence yesterday tlie waters were flowing thickly discolored, a marked difference on the water selected. When Te Arai was first thought of, it was at first proposed to obtain the supply from the Titokonui stream, two miles above Wilson's woolshed. The watershed, however, was not so favorable as the one selected, draining off cleared country, and consequently silt-charged when m flood. With the purchase of riparian rights, it would, however, always, be available .should the town- ever ■ assume / city proportions, and require' a vastly larger supply. ON THE FLATS. ' Within a few yards of the woolshed above mentioned, the pipe line makes its appearance once more across the Te Arai river, and is seen for the first time an open thoroughfare, the Arai Valley road, which is shortly destined to receive alt the through traffic to Wairoa, via Mangapoiki. From Wilson's woolshed the long and, unfortunately, most tedious task of pipe-laying to the Borough boundary at Lytton road, 16£ miles, was commenced. It being January before the workmen got clear of the difficult gorge, only a few short months elapsed before the contractors were buried m the midst of winter — an exceptionally wet one — consequently pipe-laying across tlie rainsodden flats was an almost heart-breaking job. After leaving Waingake, and until the Rae bridge is crossed, the line deviates frequently from tlie present road, on account of the latter, m many places, not being within the actual survey pegs, whilst at other points the pipe follows a circuitous route, to avoid questions of bye-leaves. Tlie largest river crossing into which the line is buried is at the ford opposite Mr H. White's homestead. Here there are -four chains of pipes m the river-bed, which is taken at an angle down stream. On reaching the bank on the town side of the crossing, 'the line, instead of winding its way round a steep incline, passes vertically over a bank 80ft m height. Here, afeo, it had been proposed to tunnel, which naturally would have been the most scientific way of overcoming the obstacle, but for the expense. At the base of the hill the line crosses the roadway, and turns upright at a 35-degree angle, the pipe being buried m the solid papa' and weighted down with seven feet of boulders. At the top a similar bend turns the elevation downwards across an easy slope. A few chains further down, at McLoughlin's cutting, a good deal of trouble was occasionedby a slip, the whole hillside at that point being on the move. The pipe line was- directed across stream to the opposite low river bank, and had not been down long when a' slip from the cutting blocked the river, turning the stream right against the pipe line. A length of 300 ft had to be lifted, and /placed on a terrace formed higher up the bank. Much of the debris has since been • washed down, and the river has now almost assumed its natural course, whilst the pipe line, embedded m a solid papa shelf, has immunity from further danger. Traversing the property of Messrs C. J. Parker and O." S. Pyke, the pipe line is carried across stream to avoid unfavorable ground, returning lower down through Mr J. C. Parker's, all of these settlers having connections with the main. The Devil's Elbow is well-known as an awkward corner, and m negotiating this the pipe emerges for a length out of the earth- on one side of the bank and reenters again on the other. For the short span of one chain which the pipe makes there is sv weight of 14 ' tons on the pipe, which has been strengthened by tvuss rods. NEGOTIATING SHARP BENDS AND BRIDGES. Thero are four acute- angles altogether m the line, points at which the pipe bends suddenly to an agle of 85 degrees, sharper tlian a right angle. In these cases it has been impossible through the contour of tlie land to sweep round m a wide curve with short*length pipes, consequently cast-iron bends had to be utilised. These angles occur at a point above Wilson's woolshed. the Rae bridge, Te Avai bridge, and Aislabie's corner, Matawhero. Spacial precaution has been taken, and the angles are anchored m solid concrete. Tlie Rae bridge, -which crosses the Te Arai river, is approached by one of these sharp angles, and the pipo. is carried across the structure suspended m iron cradles from dummy joists. At this point, and wherever the pipe emerges into tlie open, it is protected by a substantial wooden' covering. From thence to Te Arai the only points worth mentioning aro that- the lino makes an apparent deviation from the road opposite Livingstone's, but m reality follows the surveyed track, the present road making a detour to avoid an awkward ■

__ . - corner. Directly m front of Mr John Clark's gate the line takes another acute bend to cross the Te Arai bridge. The approach to this structure, it was found, was rather unstable lo carry the additional weight of the pipes, and a viaduct was specially constructed nntil the more substantial .portion of the bridge was readied. From thence to town all was fair sailing, except for the ever-present nuisance of water m the trenches. At the big .bridge at Matawhero the pipe line is carried underneath the middle of the decking. The additional weight placed upon this structure by the pipes when full is 15 tons, evenly distributed over its whole length. Much hindrance occurred m the final section ending at Te Hapara owing to the wet and rotten ground. Further trouble was experienced m the testing of the pipes, a powerful steam pump at the Rae having to be discarded through a severe frost one morning bursting a heavy casting and rendering it useless. The testing pressure was subsequently obtained from the head works. A FEW POINTS. Tlie only spot at which any real danger to the pipe line presente itself is directly behind Mr J. C. Parker's house. Here the line traverses a rich river flat, I composed entirely of river silt. Gradually the stream is returning to its old course and tliere is now an erosion to within half a chain of the pipe line, a seirious menace. It is proposed to turn the stream back across the river by substantial boulder wiers, and the bank has been planted with, willows. A fence was dug np on this flat 1 intact with its five wires. The question of labor had an important bearing upon the carrying out of the contract, no less than 1000 men having passed through the company's books. It was with extreme difficulty men could be obtained, even with the inducement of 10s per day of nine hours. Tiie discomfort of working: almost constantly m the water, both down the gorge and m the trenches along the flats was so great that the men simply left by the dozen. When the party visited the stream yesterday there was water enough to fill many nine-inch pipes, and tho inspector, Mr Wilkinson, affirmed that although he had been on the job sixteen months he had never seen it so low. All the time the operations were m progress m the gorge he was able to accurately guage the flow through the fluming and found it averaged 2,500,000 gallons every 24 hours. When the Mayor was discussing the possibility of a big drain on the supply when the freezing works and all other connections were drawn off the inspector assured the party that although he was not a betting man he would take big odds that we would never have to conserve our supply. When m flood the intake was simply unapproachable and a torrent of water poured over the dam m a straight line from the top of the wall. Air valves have been placed on all the highest points of the line and these number six on the 9-in main and 65 double valves on the 15-in main. There arealso twelve main valves where the , water may be shut off at any time and sixteen sluice valves, all m the " low-lying sections. The scheme, which was designed by Mr R. Hay, C.E., of Dunedin, has been carried out under the able supervision of Mr B. Couston, of the same city, whilst Mr W. D. Wilkinson, of Christchurch, has fulfilled the position of inspector for the Borough Council to the entire satisfaction of that body. The contract was entrusted to the. Spiral Steel Pipe Company,, of Wanganui,' the figure being £58,370. Until recently Mr G. Smithies has been m charge of the works on behalf of the company, bearing all the heavy work, having had under him as foreman, Mr A. Laird, who carried out the 'work m the gorge, and. Mr H. Willcott, who had charge of \ the men, whilst Mr. Jas. Bell was foreman from Te Arai to Matawhero, and Mr W. Reekie from thence to town. Mr Hamilton, of Wanganui, to-day assumed control of the work, for the Spiral Pipe Company. The contractors and officials have been well met by the settlers along the route, particularly by Messrs Parker, Pyke, and Sisterson, who have rendered every assistance possible. The undertaking has been one of magnitude, and the finishing touches are now being put on the job. Should enough men be procurable the contract, with its month's maintenance, should be out of hand m January. .