KUMARA WATER RACE AND SLUDGE-CHANNEL.

Kumara Times, Issue 2517, 15 July 1884, Page 2

KUMARA WATER RACE AND SLUDGE-CHANNEL.

In the Appendix to the Goldfiekls Report, Mr H. A. Gordon, Inspecting Engineer, writes to the Under Secretary Mines Department relative to his official visit to the Kumara Goldfield as follows in reference to the Waterrace and Sludge-channel : This field is confined entirely to hydraulio sluicing, and is worked by water from the Kumara Water-race and the Okuku Company's race. The

Kumara Water-race was originally commenced by a private company, but was purchased by Government in 1877, who completed its construction, and afterwards enlarged its dimensions, in order to bring a larger supply of water on to the field. [Recently a reservoir has been constructed in the Kapitea Valley above the loop-liue road to store water, so that the supply can be kept up in dry weather. It i 3 capable of supplying 100 heads of water for twelve hours per day for about three weeks, but in very dry weather the supply of water available is not equal to the present demand. The cost of this waterrace up to the present time has been about £37,367 4s. In conduction with this water-race the Government constructed the Kumara Sludge-channel as a tail-race, to enable a large area of flat ground to be worked ; it was originally 85 chains in length, constructed in a tunnel. The lower 40 chains of it is 10ft, wide and sft. high above the top of the channel aud the upper 45 chains of it 7ft. wide and the same height. But since the workings commenced the tailings from the channel have filled up a large valley between the mouth of the tunnel and the Teremakau River to such an extent that the boxing of the channel has been carried out for a further distance of about 30 chains, and very soon will be at the edge of the Teremakau River. The cost of constructing this sludge-channel up to the present time has been £17,200 12s 6d. The cost of maintaining the channel has been very heavy, and has far exceeded all estimates that were ever made. It was originally paved with wooden blocks set on end, Bin. deep; but the cost of replacing them was so great that stone paving was tried, and in order to get paving of a greater depth the sides of the channel have been raised, and 14-in. paving-stones used. About two chains of cast-iron : blocks have likewise been used, aud the result of the cost of the different classes of paving, from careful observations of the manager during the last twelve months for the lower 70 chains of the channel, where the wear and tear are the greatest (in the upper portion of the channel the wear is not nearly so great), is shown in the following table:—

S6D G o • a _a> ._ a« h . t; o "*© 5 '3 S©"> 'S « 3 n'3 g fe -S S « ° 2 o ! !°' S o 3 * s S § CM •3 a . iO O 1» OJ>J3 - £ m rH (M O ® <N y-i (M ft CM O M 2 ■ &«> . 86*8.3 <° ° I" * S? .3 d T 3 o o o eft 3 g 57" > s -» © * 3 .3 *S JS 3 .3" «> 2 to w _ J2 ° <-> S 3 O ■73 O o a m ►2-2 5 f~ OQ fl

The last item is calculated on the basis that cast-iron blocks are to be of hematite iron, and can be placed in position in the channel at £l6 per ton, which would probably be done at this »ate for a large quau titj'. The cast-iron blocks at present in use cost about £lB 10s per ton. The above table shows the cost of stone paving to be much less than any other. The coat of different classes of paving has been taken in the channel near the mouth of the tunnel; therefore the wear is all under the same conditions. The stone pavin« no doubt reduces the carrying capacity of the channel to some extent; but the manager, who Las had every opportunity of making careful observations, states that the difference in the carrying capacity of the channel between the stone and wood paving would be not more than one party each shift, and, as there are three shifts working in tha channel, and seven parties each shift, if it were wholly paved with wooden blocks, instead of accommodating twenty-one parties each day, it would enable twenty-fonr parties to work. Therefore, taking this as a basis to work on, the total rovenuo derived from parties usinij the last year

amounted to £2128 18s 3d; and, if one-eighth more parties had been able to use it, the revenue would have been iucreased by £266 2s 3d, and the wear and tear of blocks would also be increased in equal proportion. The cost of maintenance for the year was £6405 10s 8d : this would be increased by £BOO 13s lOd. showing a still greater loss on working. However, the waterrace and sludge-channel have to be taken together, and the conjoint result of the workings shows a profit of £IBB6 17s Id, or nearly 3| per cent. on the capital invested, the total cost of construction being £54,564 16s Gel. This field will take a number of years to work out, but the limited space that there is for tailings will soon become a question that will demand attention, as they will be carried into the Teremakau River, and will gradually fill up its bed, and cause the flood-water to damage the property along its banks, for which compensation will no doubt be required.