The Ararat Water Supply
Published in The Argus, Thursday 10th June 1875, page 10
By Our Own Correspondent
Some months ago (January 23) a notice of the then projected scheme for supplying the borough of Ararat with water was given in The Argus and attention was called to the fact that the reservoir would be the first of the kind attempted in the Australian colonies, the dam being designed to be constructed of solid stone work. The plans had then been examined and approved by the chief engineer of water supply, with some unimportant modifications, which having been adopted, tenders were called for the works connected with the gathering of the water flowing in three rills down the western slope of Langi-Ghiran, and the storing it in a capacious reservoir on the site selected by the borough council, on the recommendation of Mr. Gordon. Mr. William Aitcheson, who had been employed on the several works of the Ballarat Water Commission under Mr. Bagge, had been appointed to the position of engineer, and it was on the plans and specifications of that gentleman that competition for carrying out the design was invited. Messrs. Walker and Swan were the successful tenderers, at £7,243, and a contract was entered into in February last for constructing the reservoir and the pipe-head dam for that amount.
The site of the main reservoir has been already described. It is situated in one of the valleys running down from the mountain between two spurs of solid granite, barely covered with the decomposed vegetation of many centuries, in which ferns flourish in great variety, and a few stunted trees manage to struggle through a precarious existence. From the apparently inexhaustible granite formation on the northern side the stone is quarried for the purpose of of building up the embankment. The contractors have been fortunate enough to open a face in this quarry from which blocks can be obtained of any size; the solid rock readily yielding to the small wedges used in line 6in. apart, and splitting both vertically and horizontally as cleanly as if it had been cut with a knife. An occasional charge of powder is used to divide the rock into lengths, which when again operated upon by the wedges are reduced to square blocks varying from about three quarters of a ton to a ton and a half each. From the quarry to the centre of the embankment a tramway on an inclined plane conveys these blocks to their destination, where they are picked up by a powerful crane with a 40ft. jib, and placed in position on a bed of Portland cement.
At the present time the stone-setters are at work at the course on which the scour pipe rests, where the dam presents the appearance of a solid wall of square masonry of 25ft. thick. Beneath this a vast amount of heavy work is hidden in the foundations which rest on the bed rock. As every course is laid a grouting of cement is poured over the surface, which has the effect of converting the whole into an impervious mass. The sand with which the cement is mixed in disintegrated granite, washed free from all alluvial and vegetable matter, is remarkably clear and sharp, and is therefore admirably adapted to the purpose for which it is used. The cement and grouting take some 48 hours to set thoroughly. When that operation is complete the work presents the appearance of possessing the dense solidity of the rock before it is quarried, and it is evident to an observer that the season of the year is highly favourable to the construction of massive undertakings of this kind. The stone, green from its native bed, and the cement made up with the water which runs in channels among the gigantic boulders lying around, are brought together at an even temperature. No possible contraction or expansion can arise from the natural process of assimilation of temperature between the ingredients, a cause whence cracks and fissures not unfrequently spring. Here the entire conglomerate settles down on its bed at an even indication of the thermometer whether applied at the top or the bottom, in the centre of a block of granite or in the oozing gravitation of the grouting. Certainly the solidity of the work, when finished, will owe something to the evenness of temperature at which the component parts were brought together in its construction.
When finished the dam will be 544ft. in length; the greatest depth to the foundations in the centre will be 33ft., stepping up from the centre on each side, in conformity with the contour of the country. In capacity the reservoir will be equal to the storage of 15,000,000 gallons, and the water will extend over about eight acres, the surface of which is now being cleared of timber and vegetation. Apart from the springs, the natural watershed is on the high range above, chiefly formed of bare granite rock, with ferns and lichens in the clefts and crevices, where but little animal life is to be met with.
About 40 chains lower down the ravine a pipe-head dam is being constructed in the same substantial manner as that already described. It secures the flow of another rill of water, and will store 76,000 gallons for immediate use. When completed, it will be kept constantly full to overflow, from its own proper sources of supply aided by the larger reservoir above. At present a stream is flowing through it sufficient for the supply of the town. It should be mentioned that hitherto the contractors have had to carry off the water from above the dam by means of a race, constructed at some cost, through the huge boulders which are everywhere studded over the sides of the spurs. Now that the level of the scour-pipe has been reached, the water may be allowed to accumulate without detriment to the project as a whole. Between the pipe-head and the town the main is now being laid—a distance of 9 miles 52 chains—and a few months will see this part of the undertaking complete. The reticulation pipes are laid in many of the streets, and it is expected that within one year of the commencement—that is to say, some time in February, 1876—the Ararat water supply will be in full operation.
The total cost of the scheme, as estimated by the engineer, Mr. Aitcheson, was £26,000, and it is thought, notwithstanding that some extra labour has been necessitated by unforeseen circumstances during its progress, that this amount will not be greatly exceeded. At present the Government is pledged to lend the borough council £22,000 only, but no difficulty is apprehended with regard to such further sum as may be absolutely required being forthcoming, when the substantiality of the works throughout is taken into consideration.
