BOROUGH WATER SUPPLY

Oamaru Mail, Volume XXVIII, Issue 8295, 25 September 1903, Page 1

BOROUGH WATER SUPPLY

The Oamaru Borough Council yesterday took advantage oi a line day to pay a visit to the vicinity of uie intaice. ili-j object,of the visit was that t-nose who have more recently joined the civic body might, make themselves acquainted with the various sources of supply in order that they may be able to upon uio beat method of providing an abundant supp;y oi good, clear, wholesome water. buiortunately the necessity ior sometliing being done in this direction lias become very apparent by the increasing pollution of tne water supply, the liquid often coaling down in a condition resembling pea soup. Some years ago- the .Waitaki iiiver changed its course or channel and left the then intake nearly high and dry, and steps liad to be taken to procure water, and instead of cutting a race to its new cuanntl a long filtering race was cut, ten feet deep, into the shingle formation to a distance of 46 chains in a straight line towards the moutli of tli© LVlaerewlienua .River. Then two cross-cuts of ten chains each were made in different directions. .Alter putting stone culverts into these two cross-cuts, t-iio surface was filled in again. The cost of all this excavation, including a large cement culvert under a creek was about £I3OO, and the result was a supply of 200U gallons a minute .of perfectly clear water was conveyed into the race. This source has not diminished, but it. was necessary to augment it by a further 2000 gallons a minute, and occasionally more, from the river. 'This method served tlie purpose, admirably until a few mo-nths ago another flood came in the. Waitaki, caused by the melting of the enow, wliich liad the effect of diverting the whoie of' tlie Maerewhenua, sludge to the south side, of the riverbed, sending the water with this very fine brown alluvial soil in a thick solution into the race to mix with the stream of clear water from the filtering channel—hence the unwhole-some-looking liquid we in Uamaru are nowcompelled to take for all purposes, domestic as well as motive. Mr Crawshaw accompanied the .Councillors, and uie party was joined by Mr Eraser, race inspector, at, Peebles. Tlie works at tne 'intake were first inspected. Although now useless on account oi their having been silted up with soil brought down at the time of tlie iloods, there is sufficient left of tlie works to indicate that a large amount of money was spent in their construction originally. Subsequent experience, however, lias shown that it is folly to spend much money in constructing elaborate intakes, as they are sure to be rendered useless by tlie firat flood in the river large enough to alter its course. It is unfortunate that the river should have played up its pranks just now, as, what with the cost of foreshore protection and other channels for spending money, the .Council will be hard put to it to hit upon a scheme by which the money may be provided to do. such work as wui ensure clear water once again for Oamaru. The Maerewhenua, too, is not likely to become less muddy, as, in addition to all the original races at Livingstone, delivering their full complement of water, the 'Mountain Hut race will soon be bringing in eight Government- heads of water to be eagerly sought by the miners, who are always ready to take every drop of water available for sluicing. A few yards from the original intake is the present one, and at this place the junction with the filtering channel is made and the clear water is polluted by that from the Maerewhenua sludge, uie two waters run side by side for a few chains, then gradually get merged into each other. The water in the race after this is like that seen in a sludge channel, and is far worse in the afternoon than in tlie early part of the day. After seeing the water in the race the wonder is that it is fit for use of any kind when it eventually reaches tOamaru. The Council has two methods by winch it can increase the supply of clear water—extending the filtering channels, or carrying the excavation another two miles towards Duntroon, crossing the Maerewhenua with a concrete culvert and tapping a side creek of beautifully clear, percolated water which lias never been dry, and in wluch there is an abundant supply always available. This • latter method is considered the most favorable, as the Engineer and Mr Eraser estimate that the cost will be only about £650 as compared with the expenditure on the other, wliich would be probably over three times as much, and would not even then give anything like so large a body of water. It is supposed that the filtering channel drains all the water, at its level, for a distance of two chains on eacti side of it, and as there is plenty of ground to make the channels in, it is the greater cost of excavation which is against them. It is said that a race can be made by (Page's race excavator over country such as tue extended race would traverse for Is per chain. If this is so, the culvert at tile Maerewhenua would be the .only work of any importance to accomplish, and, as the land is all either vested in the Council or is riverbed or road reserve, there will be no land to purchase. The greatest difficulty will be that of obtaining money to defray the cost. While up there the Council was waited upon by ;Mr Winchester, who suffers loss by his sheep falling into the race and being drowned, with a request that the race should be fenced. iHe was assured that tlie Council would favorably consider the matter at its next meeting. • With regard to intakes, Mr Eraser says the shifty nature of tlie river makes it necessary to cut a new channel or dam up one often in order to get a good supply of clear water. The Maerewhenua sludge, however, has now set in so close, to this side as to make it' impossible to get clear water without excavating for filtered percolations or constructing something to tap the clear water of the Waitaki proper beyond it-." : There is a body of water in the Waitaki large enough to swallow up the little coming, in from tlte Maerewlieiiua, and the whole, would not suffer by the mixing, but the two —clear and muddy—run side by side for miles without mixing. Mr Eraser's experience of the river is valuable to tlie Council, and fortunately he is able to express himself practically and intelligently. The variable nature of the .WaiLaki River regarding its course, however, is ah element with which neither he nor the Council know how to reckon witu certainty, but what little knowledge the Council's officers have gained lias shown them that they must get beyond the Maerewhenua ,and consequently all the excavations nave been made in a direct-ion which would ultimately enable them to cross it. The Council are convinced, therefore, that an effort will now have to be made to obtain ths money to carry out the work. The race can ba cut and all the other work done, but advantage will have to be taken of a- time when the Maerewhenua River is low to put a culvert under it, as it can only be done while temporarily diverting its course. Oamaru will, therefore, be compelled to use water more or less cloudy for a protracted period unless the water is used more sparingly. It is evident that thj filtering channels give considerably more than is required for domestic supply, and if the race were kept going continually with this water only, and absolutely no water was aiiowed to run to waste, there would be little, if any, necessity to take in me sludge. At any rate, it is evident that some arrangement should be made to so- reduoe the quantity of sludge water taken in as to render its presence imperceptible. The matter will come before. the Council at its meeting, to-night, when the Engineer "will, no doubt, be instructed to prepare plans and estimates.