LAKE COLERIDGE.

Press, Volume LXIV, Issue 19212, 19 January 1928, Page 6

LAKE COLERIDGE.

generating equipment. IMPROVING WATER STORAGE. Specifications have been prepared and tenders have been called for the generating unit which will complete the present capacity of the Lake Coleridge power station. Like each of the two most recently installed generating units, the new unit will have a capacity of 7500 k.w. The nominal capacity of the station at present is 27,000 k.w. - when the new unit is in operation'it will be 34,500 k.w. The tenders for the new unit close on May 29th this year, and the machinery is to be delivered by March Ist, 1929. Under the new scheme of numbering the generating units, tunnels, and pipelines at the power station, the generating unit last to be added will be No. 1. Tenders have been called for the necessary pipe-line and close on May 29tli this year.

Improvements at Harper River. For some months past it will have been noted from the weekly reports that the average inflow from the Harper river has been very little, amounting only to the equivalent of a trickle. This has been due to the fact that a new outlet weir is under construction and repairs to the intake gates are in hand. The new weir is of a special type, with an adjustable gate 15 feet wido. By using this gate it will be possible, when necessary, to raise the normal level of the lake, which is 1670 feet, to 1672 feet. The work of constructing this new weir, which is downstream from the old one, will be completed, it is anticipated, about the end of February. The repairs to the intake gates will be effected, circumstances permitting, in a fortnight or three weeks.

Advantage has been taken of the opportunity while the repairs to the gates are being effected to make an alteration to the dam. The wing wall has been lowered to a certain level, and stop boards have been put in between that level and the top of the dam. When the river is in flood and is bringing down large quantities of shingle and boulders, some of these boards can be lifted and the flood waters "topped"—that is, the water at the highest level, which does not carry shingle, will be able to find its way into the race connecting with the lake. Hitherto, when the river has been in flood, the gates have had to be closed completely, as the shingle and boulders would soon have blocked the race. The improvement made at the dam will allow some of the flood waters, but none of the shingle or boulders, to reach the lake.

Inter-Connexion of Water System. Recently there was completed work which will add to the general efficiency of the power station. This was the construction of cross tunnels connecting up the No. 1 and No. 2 intakes and the No. 1 and No. 2 surge chambers. The work recently completed was the putting through of about 10 feet of the tunnel connecting the two intakes, the other portion having been excavated when the work of extending the station was in hand. The 10 feet mentioned could not be done then because it would have meant closing down the station. The No. 2 tunnel (the first constructed) was closed down for a time by means of a bulkhead at the surge chamber end. From the No. 1 surge chamber sufficient water was conveyed to the No. 2 chamber to keep ono of the original generating units in commission; Nos. 2 and 3 units (each 7500 k.w.) were kept in operation by the water from the No. 1 tunnel and its pipe-lines. While the No. 2 tunnel was empty it waa inspected for cracks, and these, when found, were repaired.. The effect of the inter-connexion of the hydraulic system will be that in the event of either of the intakes being put out of action, the other will be able to supply water for both tunhels.