The Langi Ghiran Water Works
Published in The Argus, Friday 18th May 1877, page 6
By Our Ararat Correspondent
About a year and a half ago a brief description was given of the works in operation for the supply of water to the borough of Ararat, and as the scheme is now so far completed that the burgesses are in the enjoyment of a reasonable hope of being possessed for the future of that greatest of all comforts in an Australian climate, enough and to spare of pure mountain water, a further notice of the first solid stone dam of any magnitude constructed on the Southern continent cannot fail to be of interest. The project has not been carried out without difficulties and hindrances, some natural and others avoidable, which are worthy of record for the benefit of localities contemplating similar undertakings. It has come to be considered inevitable that a certain amount of bungling must interfere with every water supply scheme in Victoria, either in inception, calculation, management, or maintenance, and this quality has not been wanting in that under notice, but fortunately without involving any very large amount of wasted capital, although some cost and no little delay have had to be borne in consequence.
Several years ago it was proposed to divert from the Mount Cole Creek a joint supply for Ararat and Stawell. Along this creek runs in all seasons a stream sufficiently copious to admit of as much water as is likely ever to be required being run off for mining and sluicing purposes. After much talk this proposal fell through. Had it been supported as it deserved, both the mining towns named would have been long ago in the enjoyment of a superfluity of water such as can never be obtained from the separate sources of Langi Ghiran for Ararat, and the Grampians for Stawell, and at a far less cost than the plans since adopted can be completed for.
After the loss of much valuable time, and the migration of thousands of miners from Ararat, Cathcart, Armstrong’s, &c., the necessity of procuring a supply to the borough of Ararat for domestic and business purposes merely became imminent, the watershed of the Langi Ghiran range was surveyed, and the locality at present utilised was adopted, with the approval of the chief engineer of water supply, Mr. Gordon. Applications were invited, and Mr. William Aitcheson, an engineer of several years’ practical experience in hydraulics, was selected to design and carry out the works. The streamlets running down from the mountain were examined and their capacity measured; shafts were sunk to the granite rock on both sides of one of the gorges in several sections. The results of these were submitted to the department, and the site on which the dam now stands was decided upon. Plans were prepared, Mr. Aitcheson adopting the granite, of which the mountain is composed, as the material of the dam wall. Tenders were called for the earthworks and walling, and the lowest, that of Messrs. Walker and Swan, for £7,242 was accepted. This portion of the work was commenced in April, 1875, and completed in May, 1876; and as nearly a year has since elapsed, the stonewall may be pronounced to be fully equal to the pressure it is called upon to bear.
The storage provided by Mr. Aitcheson include a reservoir shut in by a granite wall 632ft. long and 42ft. high in the centre, and a smaller one lower down the gorge 52ft. long and 13ft. high, as a pipe-head dam. The wall of the larger dam is a mass of masonry. It is of the length just stated, with a base of 28ft. 7in. at its greatest height, diminishing on each side as it strikes the natural contour of the bed of the solid rock on each side of the valley. In the deepest portion of this wall it is built on the point or water side with a slope of one in 10 to the height of 12ft., after which it is carried up vertically. The back or outside has a slope of 1 in 1·43 for 12ft., 1 in 1·66 for 20ft., and 1 in 2 for 5ft, the top 5ft. being vertical, of a thickness of 3ft. 6in. All the stonework is built in cement in 18in. courses, and grouted. The stone used was quarried out of the spur on the north side in large blocks with even beds, and the entire structure is as strong as the best ashlar work. (On this point a difference arose between the contractors and the borough council—the specification directing the work to be rubble-work, in thinner courses—which was made the matter of an action at law, and eventually decided against the contractors; and it may now be said, without injury to either party to that suit, that the borough has got a very solid stone wall at a very moderate cost). An overflow of 69ft. long and 4in. deep is formed near the centre of immense blocks of granite, the fall of water from which, when the reservoir is full and the streams are running at their full winter rate, and occasionally during summer floods, will be one of the sights of the district. There are two outlet pipes, one 15in in diameter, built in below the natural surface of the creek bed, intended for a scour-pipe, which will be used only when the basin formed at the mouth of the supply-pipe is silted up. This latter is placed about 2ft. higher, and the entrance to it is protected by a strong iron cage, with strainers of galvanised iron of a quarter of an inch mesh to prevent the escape of fish. Outside the pipe, the channel is pitched for some distance until it joins the overflow channel.
As regards size, the reservoir, when full, covers an area of just over five acres, and contains 15,200,000 gallons. Its outlet pipe discharges at an elevation of 550ft. above the post-office, which is built on the highest site in the borough. Its storage is equal to seven months’ supply of the demands at present to be made upon it, calculated on the most liberal rate. The immediate watershed is comparatively small, comprising 320 acres of the mountain standing above, from which a constant stream flows, with more or less volume according to the rainfall, but which has been at times nearly dry during the protracted drought of a season which cannot even yet be declared to be altogether over. An additional supply is obtained from the Easter Creek, which flows from the same range of hills for the greater portion of the year between two spurs adjacent, and which is diverted by means of an aqueduct 17 chains long, cut through the dividing range or watershed line, and by a channel through granite pitched and grouted in cement. During more than half of an average year the flow of the collecting streams into the reservoir will yield a considerable surplus for storage over the current demands for supply, and it is estimated that the overflow will be kept running for probably about six months.
At a distance of six furlongs from the main reservoir, and at an elevation less by 245ft, the smaller or pipe-head dam is constructed, also in solid granite. Its holding capacity is stated at 70,000gal., and into this, along its natural channel, flows the Southern Creek, running in from the drainage of other spurs running down from the mount. It is calculated that the steady flow from this creek is sufficient to supply the present wants of the borough for the winter months and the early spring, without recourse being had to the main reservoir. This does not apply to an exceptional season such as we are now undergoing—a season in which streams from the larger mountain ranges in this neighbourhood have been reduced very considerably in volume, and in some instances have ceased to run. However, with the occasional rainfall of the close of the past month (April), the Southern Creek was found equal to the supply of two days in the week. In dry weather the pipe-head dam is kept full by a regulated discharge from the reservoir above. The mains are connected with this lower dam, the outlet pipe being 10in. in diameter, and conveying the water to the valve-house, distant 60ft. A 10in. scour pipe is provided for running off the water whenever it may be found necessary. Every care is taken that nothing but water can find its way to the outlet, which is guarded by iron gratings and screens of fine wire fixed over a well built up to above the outlet level, the screens being separately removable for cleaning when necessary.
From the valve house to the western end of the town proper a 7in. main has been laid—a distance of 9 miles 38 chains. In its length are six stop valves, four scours, and eight air-cocks. This main is calculated to supply 150,000 gallons every 24 hours. It has to bear a pressure of 132lb. to the square inch at its highest point in the borough, and 1851b. at its lowest level near the Green-hills Swamp. And it is with respect to this matter of pressure that the burgesses have been made to suffer unnecessarily, something in pocket and no little in inconvenience and delay. And this arose from the bungling alluded to above. When a contract was entered into for the supply of these 7in. pipes, it was made a condition that each and every each pipe should be subjected to a test of 250lb., and this condition was carried out with the first instalment, among which many were rejected as having given way under experiment. At this juncture, an expression of opinion was obtained from a high authority that the hammer test was enough for everything, and it was stated that a continuance of the hydraulic test would be the cause of no end of delay in the delivery of the pipes. In an evil hour the council gave way, and they have since suffered for it by having had 106 pipes burst along the line, and by being put to considerable expense in adding a reducing valve to their appliances, the object if which is to lower the pressure of the main to a maximum of 120lb. to the square inch. Not one of the pipes which were passed under the hydraulic test has given way, while many of those subjected merely to a trial by hammer were proved to be very irregular castings, delivery of which should under no circumstances have been accepted. The borough council must, however, be exempted from blame in this matter, as they were overruled by the department, and their engineer had no hand in it, for the pipes were purchased before his appointment was made. It will be of advantage to other corporations to bear the lesson in mind, and to insist on the high-pressure water test as a condition in future contracts. The money loss sustained by the council may be moderately stated at £450 for the 106 “bursts,” while the loss on each separate occasion of from four to nine inches of water in the main during a season of drought has been the cause of something more than annoyance—suffering. Supply has been cut off without a moment’s warning, and although the discoloured water of the Oliver’s Gully dam has been turned on with praiseworthy alacrity, the evil has been endured, and the outcry has been natural and sustained. It would be difficult to compute the sum of this in £ s. d., but it would be found to be an appreciable item in the balance-sheet if it were worked out.
The total outlay on the works up to date may be stated at £36,000; the reservoirs and their sources costing nearly £13,000, the pipes, and cartage of the same £15,000, laying the main £1,000, and the reticulation of the borough, fencing, compensation to landowners, supply pipes, the reducing valve, stop-cocks, fire-plugs, standards, interest, law-costs, and superintendences making up the balance. About £750 was wasted in law, which might perhaps have been avoided; and the council was involved in an action with the contractors for the reservoirs which threatened an appeal to the Privy Council. The contract for these works was at a schedule of prices, and a dispute arose whether the main dam wall of the great reservoir was not something more than the “rubble walling” set forth in the plans, and described in the specification. On this question there was a conflict of opinion among engineers, and an offer was made by the contractors to submit the difference to arbitration. If this course had been adopted it is probable that the amount wasted in law would have been shared between the contracting firm and the council; for it was known that the engineer, while repudiating the amount claimed as an extra, was favourable to the granting of a bonus for the superior character of the work. The action proceeded, the contractors gained a verdict at Nisi Prius for their entire claim, which was not, however, sustained by the full Court. Notice of appeal to the Privy Council was given, but ultimately the contractors took what the Court had awarded them, with costs against the borough; and this expensive and unnecessary litigation was brought to an end, and the money paid over. The bulk of the capital expended has been advanced by the Government at 6 per cent., of which 4 per cent. is payable as interest, and 2 per cent. in reduction of the debt.
Of the quality of the water there is no room for two opinions; its softness and purity are admitted on all hands. Up to the present time it cannot be called brilliant, although it looks so in a decanter or other glass receptacle, for in bulk it presents in a modified degree that “opalescent” quality which is to be found in the Yan Yean, but when it is borne in mind that the reservoir has never yet been full enough to overflow, and that nothing was done to the vegetation of the natural surface which forms its bottom, the expectation that this peculiarity will disappear with time is not unwarranted. Now that the last few feet are being drawn off, there is no appearance of any deterioration. And a practical proof of its wholesomeness was afforded a short time since by the authorities of the Ararat Asylum for the Insane. In order to reduce the monthly water rate at that institution it was directed that a portion of the supply should be drawn from the tanks formed for storage of the roof water. This was done. Diarrhœa and other disorders became prevalent, and typhoid fever appeared, in two instances terminating fatally. Beyond all doubt the cause was traced to the use of the tank water, which no intelligent person of a month’s experience in the building would touch. Its use was prohibited, and the health of the patients was at once restored. It would be a cruel act indeed if the patients were debarred from the plenteous use of this necessary of life in the purest condition obtainable. And as for the tanks and their contents, as to the cleanliness and wholesomeness of which all control is impossible in a building of this kind, where wards and corridors overlook roofs at various levels, it would be as well to cut off all connexion between them and the supply system, and to divert the water to irrigation of the lower portion of the grounds, where plantations might be formed and inexpensive fountains made to play about the approaches in a manner to relieve the stark desolation of the aspect of this sad institution of modern civilisation.
Mention has been made above of the Oliver’s Gully reservoir in connexion with the supply under notice. This is situated about a mile to the south-west of the town Its storage capacity was set down in Colonel Sankey’s report at 19,615,554gal. Its collecting channels extend over a considerable area of abandoned “diggings,” along which no small quantity of silt is mixed up with the rainfall. In the bulk the water has the appearance of weak coffee. But, upon this reservoir the borough has been dependent during the times of repairing the 106 bursts previously noticed; and even now, while rain is being anxiously looked for, it is looked upon by the inhabitants as their “stand-by.” At some future period, when the borough has recovered from the exhaustive effect of its first outlay, this reservoir will be incorporated with the Langi Ghiran system. Since Colonel Sankey’s report was issued a considerable addition to its storage capacity has been made by the adding to the height of the earthwork of the dam wall, and by raising the by-washes. At the same time the “silting-up” process has been in constant operation. With a comparatively small outlay this reservoir might be run off, cleared out, the accumulation of silt removed, the collecting drains cut off and diverted and a square compact basin formed of tolerably even depth capable of holding 25,000,000 gallons at the lowest estimate. To this subsidiary reservoir the Langi Ghiran main could be extended (connexion being already formed) and during the rainy season kept constantly flowing, so that 15 months’ store might be laid up in the two receptacles. The computations of the engineer show that the flow of the several creeks on the mountain in ordinary years is fully equal to such a demand upon it. All that is required to make the Ararat water scheme a perfect one for all seasons, capable of keeping ahead of the natural expansion of a growing township, is the expenditure of some £2,400 in addition to that which has been already incurred. But perhaps for the present the borough council will have to rest from its labours in this direction.
