Dredging at Waikaia.

Progress, Volume VI, Issue 9, 1 July 1911, Page 721

Dredging at Waikaia.

(By A. Gordon Macdonald.)

A . rather novel method of dredging is being carried on at Waikaia by the Mystery Elat G. D. Co., by means of which ground hitherto considered fit only for sluicing- is being worked by the dredge. After dredging all the available river flat, the dredge is now working its way up the gentle slopes of the terraces and foothills surrounding the river flats. To do this, water has been brought on to the claim by means of a race some two or three miles long, and commanding ground at an elevation of about 50 feet above the river level. The dredge works in a paddock supplied by this race and continually stacks the tailings behind, forming a dam to keep up the level of the water in the paddock. As the ground is shallow a tailings elevator is not required, the dirt being washed through a sluice-box, as shown in the illustration. It was found that the tailings dam would not rise with the rise of ground unless a low dam was first built up to hold the bulk of the tailings. . Once started in

this manner the tailings keep building an efficient retaining wall for the paddock. These low dams of sods and brush will probably have to be built up occasionally as the dredge advances and rises. At the present time the dredge is some thirty feet above the river level, and it is the intention of those in charge to work right up to the water race. After reaching that level pumping will be necessary to keep the paddock full, for the present intention is, if possible, to work over a low saddle at an elevation of about 50 feet above the level of the water race, and so into another gully, down which the dredge will work its way to the river again. From the progress -already made by the dredge, it would appear that this method of working is quite successful, and it may come about that ground so far considered unworkable, owing to the lack of water for sluicing, may yield profitable returns when worked by dredging' in this manner. At all events, the immediate future of this dredge will be watched with interest by all associated with the progress and development of mining, and of dredging in particular.