BIG BLASTING OPERATION.

Otago Daily Times, Issue 19275, 12 September 1924, Page 7

BIG BLASTING OPERATION.

J 6.000 TONS OF BOCK DISLODGED. THREE TONS OF GELIGNITE USED. (From Our Own Correspondent.) AUCKLAND, September 11. A notable blasting operation was carried out at the sone quarry on the Waikato River bank, near laukau, by Mr W. A. INeed, contractor, yesterday, when three tons of gelignite were exploded to obtain metal for various reading contracts. These contracts include a supply of 50,000 cubic yards of metal for the • Taukau Borough Council and supplies for the Public Works Department, works on the Ratigiriri deviation, Raglan and Franklin County Councils,’ and Hamilton. Preparations for the blast had been in progress for some time, a long shaft having been driven into’ the mass of rock. Two cross tunnels were bored at right angles to • the main shaft, and at the ends of these the explosives were laid. The main tunnel was 75 foot in length, and the length from the gelignite to the mouth of the tunnel was filled with concrete. The shot was one of the largest of its kind over fired in Now Zealand, and was under the charge of MV John R. Leggo, technical adviser to the Nobels Explosives Company (Ltd.). The shot was fired electrically from the Taukau bank of the river There was practically no noise, but the ground was shaken as if bv an earthquake for 3' distance of more than half a mile around. The whole hillside appeared to lean outwards, hover as if in indecision, ami then fall with a terrific crush. By means of the blast 36,000 yards of rock wore brought down, while a further 15,000 to 20,000 yard.s were shattered or loosened. The fall gave the contractors sufficient metal to supply them for the next 12 months at a rate of consumption of about 200 yards per day.