SILTING COMMISSION.

Auckland Star, Volume XLI, Issue 134, 8 June 1910, Page 5

SILTING COMMISSION.

AST, INGENIOUS SUGGESTION. The Commissioners—Messrs. Ferguson, Mtchelson, Vickerman, and Flatman— continued hearing evidence at the Government Buildings this morning, concerning the silting up of the Ohinemuri and Waihou rivers.

Mr Myers (for the Mining Companies), handed in a letter lie had received from Mr W. G. Mowatt, of Karongahake, outlining a scheme for dredging the rivers to cope with the present difficulty. J. A. Pond, analyst, called .by Mr Mueller on behalf of the Ohinemuri Eiver Silting Committee, said the effect of.-the silt going down the river would ultimately have the effect of forming deltas at the mouth of the WaihoiL He favoured depositing the residue from the mines -on poor land, and was satisfied from experiments he had made that certain grasses, legumes, and trees such as pines would grow in silt, provided the depth was not too great for capillary attraction to appear. Dealing -with the question of the disposal of the slimes, Mr Pond said pumping was sure to meet with failure, but movement by vacuum or pulling forward was feasible. The Waihi Company proposed to get 10,000 horse power by harnessing the Horahora rapids. Seven or eight miles further south there was a most suitable gorge where 40,000 h.p. could be obtained, and the utilisation of this "would give the power necessa-ry for dealing with the slimes by vacuum. He proposed depositing them on the plains of poor land between WaShi and the Tauranga river. The surplus over the power required to transmit the slimes could be profitably sold to the mines, and even as far as the Thames. He had not gone into the details, but made the proposal for what it was worth.

In answer to the Chairman, who wanted to know whether steel pipes would stand the wear, Mr Fraser, of the Waihi Company, said the suction side of their pumps did not show so much wear as the discharge, showing that where the slimes were sucked they did not cut the p-ipes as much a3 where they were forced.

Mr Pond, replying to one of the many representatives, eaid if they got 40,000 h.p. from the Wa.ika.to, used 10,000 in dealing with the tailings, and sold the ■balance, it was a better scheme than allowing the silt to spoil the lands along rivers as at present.

Mr Gauvaine (Waihi Company) said his experiments showed that with the proportion of water and slimes as 3 to 1, a lift of about 18 feet could be obtained, so that a number of vacuum stations would be required to get any height. He reckoned Mr Pond's scheme eoulcl not cost less than half-a-million.

Mr Myers remarked that the scheme was cv the Government might consider. He <ii« not think the Mining Companies could do so.

Mr. Cotter (for the Ohinemuri Borough Council), in opening his case, said the Council considered a dredge absolutely necessary in the river, and also favoured stop banks. They viewed the proposed cuts in the Waihou and Ohinemuri rivers with doubt, both as to expense and results, and did not think the suggested depositing of the silt at Eotokohu Swamp either practicable or desirable. He contended that the Government had the power to revoke the proclamation of the Ohinemuri as a sludge channel, but the Council did not wish this until a serious attempt had been made to find a remedy. Perhaps there should be some modification, such as prohibiting any use of the upper Waihou by future companies, and insisting that everything put into the Ohinemuri by the mines should pass through a 100-mesh screen. The companies had all talked about the extreme fineness of the present grinding, but the Council thought it advisable to have some such restriction as he proposed. Mr. Cotter drew attention to the limited rating area in the Ohinemuri County for raising funds, and said the Council had felt that it was useless for them to try and deal with the difficulty now being investigated, as it was quite beyond them. The Council suggested that a new body should be constituted, with rating power over the watershed of the Ohinemuri and Wailiou (as far as Shaftesbury). The Council considered that the gold duty should bear the whole of "the cost of stop banks, clearing the river and dredging, the annual expenditure being estimated at £6,000 a year. In the alternative the Council suggested the proportion of contribution should be one-half from the gold duty, one-sixth from the Ohinemuri County Council, onesixth from the Government, and onesixth from the mining companies. (Proceeding.)