TAIERI DRAINAGE

Otago Daily Times, Issue 16339, 23 March 1915, Page 2

TAIERI DRAINAGE

THE LAKE PUMPING STATION. It would ssem that many problems in Taieri Drainage have yet to find their final solufc.oh. Soma of the questions with which the Western Taieri Drainage Board is at present faced were dealt with in a report from the engineer that came before the board at its meeting yesterday. In the absence of the board's chairman (Mr J. T. Gibson), it was decided to hold over the report till next meeting-. Ttto ' report is as follows:—"The old pumping plant at the Lake" Pumping Station is considerably out of repair, and should I think, now be nut in working order. The extent of the rena : rs and refitting required will depend on the class of work the plant is requ.red to cope with in the future, that is, whether it is to assist in the ordinary pumping of. a wet season, .or to act as a stand by to be used in case of flood only. The extreme limits of work the wheel could -undertake in the past, and as it stands now, is. to lift water from 0.50 in the drains to 4.00 in the lake, that :s, to a total height of 4ft 6in. These are the'" extremes. Whexi the late rises above this level the wheel as it now stands and with the present steam plant cannot be worked. If the wheel is to act as a stand by, only to be used to ass.st the electrical plant in time of flood, or in case of a break clown <>f. the electric power during a flood, then it would seem advisable to lift the wheel to allow of its working at all levels of the lake. In deciding this matter, however, there are several points to be taken ; into consideration, and I have grouped these into the following alternatives:—(l) in any case, the timber work of wheel requires to be renewed and some of thp. iron work altered and repaired. (2) To raise the wheel Ift o.n and use the existing steam plant as the driving power. In this case the wheel could work at practically all the levels in the lake, but couid not ao effect.ve work ujtil water in the drains rose to. about level 1.50. This level is , pract.cally low land level near the numo station, so that the ■ svheel could be use'd only under Hood conditions. It is probable tnac extensive repairs will be required on the existing steam plant. (3) To keep the wheel at its present level, but increase the driving power, so as to pump at a high .lake. The wheel could thus be ut lised to ; assist the present electrical plant in case of need be in heavy rain. ' It would do good work when the- water in the drains rose to 0.50 (that is, one foot below low ground. Henley). Also by increasing the aepth of the wheel blades, the extra power installed would bs used to increase the output when the lake level was normal or slightly below normal. (4). To raise the wtieel lft 6m as in (4, but to increase the depth of blades and the driving power. The wheel could be used onlv under Similar conditions to (2), but by increas.ng the power the output under those flood conditions would be increased.

In regard to thr; question of the most suitable driving power—steam or electric the latter is certainly the better, both as regards running cost and handiness in working, especially if it is decided to keep the •wheel at its present level, when it would be most often in use. The present steam plant caused considerable expense during the last two years in boiler repairs, and cannot now be relied on; also tne steam pressure will probably be reduced in the near future. A new fire box. at least, is required, or probably it would bo found better to v connect up a new boiler to the present engine, which, I understand, is in fair order. In deciding on this matter the possibility of a lengthy break down at Wapori Electric Power Station and the advisability of having a. steam plant as a stand by has to be taken into* consideration.

In regard to the question -whether the wheel should be raised or not raised the only advantage in raising tho wheel would be m case of a break down at Waipori when the steam plant, if put in repair, could be brought into operation during a high lake. Unless the present steam plant is put in repair there does not appear to be any advantage in raising tho wheel as the existing electrical plant is capable' of pumping at all levels of the lake. The act of raising the wheel, however, prevents its use until the water in the drams i» up to near flood level at Henley. So that if a break down occurred at Waipori, say, under ordinary wet weather conditions, the steam plant and wheel could not be used until the lower plain was getting flooded, when possibly by that time the lake, if it were high would have fallen; whereas if the wheel was at its present IC vel it would be working all the time if tho lake were not too high, or could start working immediately it fell sufficiently low. In the case of a Waipori and Taieri Kjvcr flood on the plain the _ water would, of course quickly r:se to a k-yel high enough to allow of the wheel working , but under these condit : ons it is not advisable to start panning until a considerable portion of the water has been mil out by gravitation, when, of course, the lake level will have fallen. For these reasons I am of opinion that proposal No 3 is th> best, that is, to keep tho wheel at its present level and increase the driving power so as to work at a higher lake than at present, and to increase the output at a normal lake level. It will of course, not ho able to lower the water to the same depth as the present electrical plant under normal conditions by about 411. but it could relieve the present plant by takmg say, tho Lee Creek drain water which will not rrquiro to be lowered to the same extent as the ether drains. Also when heavy pumpm-i is required, the using oE the wheel will often confine tho pumr£ ing to the night hours, and oheaner nower rates when otherwise, day pumping,' with the heavier ratos and a double shift m:"«-ht bo required. The renewing of the timber work ot the -wheel and the increasing of the driving power is work quite arjart and separate from tho ra : sing of tho wheel so that the \7llcel could be raised afterwards if neccsarv.