THE DUNEDIN WATER WORKS.

Otago Witness, Issue 802, 13 April 1867, Page 15

THE DUNEDIN WATER WORKS.

In the last report submitted to the Dunedin Water Works Company, on the 22nd February, it was intimated that the one important item of the works, the construction of the reservoir, was in a forward state, was being vigorously carried 00, and was in a fair way of being completed on an early date. This description is, in every "particular, considerably more applicable now than it was then. During the interval there has been an increase in the vigor with which the contractor, Mr Proudfoot, had latterly carried on the work, and the " early date " of completion may now, with some confidence, be placed within the next two months. As tbe date •of completion approaches, the works are becoming daily more worthy of a visit. Many as are the visitors attracted to the valley of the Water- of- Leith by its natural picturesqueness, few are aware of the amount of practical work which is being daily gone through in its immediate vicinity, by the crowd of men and horses employed in the formation of the " head- centre" of the Duncdia Water Works. The situation is a secluded one, and little sought by the way-farer; but a spare hour may be very profitably spent in a walk up the Leith Valley, and in an inspection of one of the first important public works of the Province. In a month bence, especially, tbe work will be at such a stage of completion as to enable a judgment to be formed of the labor and capital that have been expended, and of the probable value of their result.

The reservoir is reached by leaving the proper valley of the Water of Leith, and oy proceeding up its left hand tributary, Ross's Creek, which joins the main stream at the Woodhaugh Mill, where Mr W. R. Douglas has recently introduced an industry interesting to agriculturists and market gardeners — the crushing of bones for direct application to the soil, or for manufacture into superphosphates. About half a mile above this mill, the visitor is confronted by a considerable impediment to a further view of the pretty glen through which he has walked. This is the main embankment of the reservoir, and a i very rough intrusion upon one's view it is at present, but, when completely formed, it ought to look as ereen and fresh a3 any of its surroundings, as it will be smoothly " faced" and sown with grass. An estimate of the amount of labor which has been executed by pick and spade in the construction of this part of the work may be formed, when it is stated that it already contains 60.000 yards of earth and puddle, and before it is brought to its full dimensions, it must receive 10,000 yards more. Along its top, it will be 330 feet longthat is, from one side of the valley to the other — with a breadth of 15 feet on the crown, and 375 feet on the base. On the upper side it will stand 50 feet high, and of an equal height is the "well," or tower, from which the supply of water is regulated, and which has already been constructed. The slope inside is 3 feet to 1 ; outside 2to 1 ; and the odds are a great deal more than two to one that, thus constructed, the work will stand all the pressure that can ever flow by this course from the watershed of Flaastaff Hill towards Dunedin Bay. The formation of this huge clay wall is at present giving employment to 60 laborers, 16 drivers, 24 horses, and as many wheeled vehicles — " dobbins " and drays. According to the original specification, the earth of this embankment was to be laid down in two feet layers ; now it is spread in layers of one foot in depth. The puddle trench, or the " spinal marrow" of the embankment, is ten feet in width, taken down to the solid rock in the, bottom, and its extremities extending into the rock of the hill-side also. The inside slope will of course, be "pitched," or faced with stone, ot which abundance is procured in the execution of the earthwork; and it is expected that the embankment will be ready for this part of the work being undertaken in less than a fortnight. The exact dimensions of the reservoir we have not been able to ascertain. It was the original calculation that it would ac-

commodate ninety-seven millions of gallons, but the bottom of the valley, or natural basin, which has been selected a3 the site of the reservoir, has not been excavated to the full depth intended. It has, however, been levelled down until just the traces of the serpentine course of the natural stream are visible ; and, whatever numb.r of millions of gallons it may contain, it ought to hold enough of water to cleanse the throat of Dunedin most effectively, and to wash it, bathe it, and put it to bed at night without any serious apprehension of an outbreak of fire. "Sections" are to be taken shortly, or are being taken; and some estimate can then be formed of the superficial acreage, the depth, and the number of gallons, pints, or half- pints of water which statisticians may be desirous oi knowing it is likely to contain. The " well," which rises from the inner edge ot the base of the main embankment, is a tower built of Port Chalmers etone. Strangely enough, although the sides of the valley

thrtfagfi which the stream runs, show abundance of rock on each side, and are quarried somewhat extensively, Mr Proud' 1 foot found it more to his advantage to use i Port Chalmers stone, than that immediately at his hand, notwithstanding the additional cost of carriage. From quarries in this valley, in the possession of Mr M'Glasban, material is at present being taken for a steim flour mill, being erected by Messrs Anderson and Mount, on the reclaimed ground at the south end of Prince* street ; but for the purposes of the reservoir well, the other srone was preferred, beinjj less brittle, and consequently less liable to waste in being dressed and laid. This " well" stands fifty feet high, is 13 feet wide outside, and four feet square inside. It is, in fact, the shell of the apparatus which is employed in regulation the supply ot water to the city. For this purpose it contains two "inlet pipes," and two " waste pipes," each fourteen inches in diameter, and supplied with valves to be managed from the summit of the tower, which, when the reservoir is filled, will only be visible as a minute island in the middle of the water. Although thus modest in appearance, compared with the dimensions of the work, it wi'J, however, have the merit of regulating the whole action of the valuable agent by which it will be surrounded.

At the upper extremity of the big reservoir is another embankment — the first constructed item of the water works. It is 35 feet in height at the centre, and already encloses a body of water sufficient for the' supply of a pood-sized community. It. forms the "supply basin," and for that purpose is complete ; but it has yet to be finished on the lower side by bfcing "pitched," so as to take its part in the holding of the great body of water to be imported, in due time, into the main reservoir. From it, on the left hand or northern side of tbe valley, to below the great embankment, extends tbe storm channel, 1100 feet in length. This is a substantial water-race, built of the blue stone of the neighborhood, nine feet wide and four in depth. It has already had the trial of an extensive flood, and beyond the carrying away of a small portion of embankment, has proved itself equal to the event ; but of course, there will, in future, always be the extra escape of the large reservoir, and its " byewash." It is on the opposite side of the main reservoir where the body of laborers rmployed arc at present at work. To form tbe great embankment, they are here excavating extensively along the side of the hill, from the one embankment to the other, until a complete and broad carrioge way has been formed alons the fide of the reservoir. From this same source of supply, other ten thousand feet of material will be taken ; and, with that done, the finishing touches |of " facing," and puttins the reservoirs in condition for the reception of the water, will be commenced. The works are at prssent being carried on under the inspection of Mr Crawford, Mr Balfour being the engineer, and Mr D. Proudfoot, the contractor.