Rock Supplies May Limit Harbour Breakwater Plan

Press, Volume XCVII, Issue 28658, 7 August 1958, Page 17

Rock Supplies May Limit Harbour Breakwater Plan

Three possible sites, - one at Evan’s Pass being most favoured, for supplies of rock for the harbour extension works breakwater, inside which overseas ships will be accommodated, were given by Mr J. A. Cashin (engineer-in-chief) when he was questioned at yesterday’s meeting of the Lyttelton Harbour Board. Reporting on three subsidences on the breakwater from June 28 to July 12, Mr Cashin said an area of reclamation, roughly 180 feet by 60 feet, was washed down by wave action to about low water level. No material was lost, as it was displaced into the area to be reclaimed.

Mr W. B. Laing said he hoped the engineer was right when he said no material was lost. Discoloration went well down the harbour during ranges. Some members of the board had not seen the range, which made the engineer’s job difficult. Good work was being done by the men in the quarry but the quarry did not have much ‘‘A” grade rock at the face. Future Supplies Had the engineer anything in view for the supply of good stone? asked Mr Laing. Buckley’s Bay was a likely site, he suggested. The quantity of 39,000 tons of rock shifted last month was a record for a single shift, said Mr F. I. Sutton. Did the engineer intend carrying the breakwater well out into the harbour or did he intend to reclaim land behind the quay?

Nothing serious was,lost by the wash-down, replied Mr Cashin. After a storm, the whole of the harbour appeared to be white: in fine weather, it was blue. Tests by the finest methods could find no difference in the amount of material in suspension. The discoloration was more apparent than real, so there was no need for worry about the amount of material going, out. Most of the material would be a small amount of clay going out Ever since the work was begun, he had been anxious about the supply of best stone, said Mr Cashin. He had said so on several occasions. “Fortunately, we have had just enough to keep us going.” he said. “If we don’t get enough, we can flatten the slopes, ,which would be more expensive. But so far we have got on without much difficulty and we hope we will continue. “But there ’is no guarantee about it.” Three Sites ( Three sites for quarries round the harbour had been in his mind, said Mr Cashin. If Evan’s Pass was the site, the old road would have to be re-opened. It was one mile and a quarter away from the works against a quarter mile to half a mile at present. It was not intended, at the moment, to continue the breakwater to its full length, because a certain amount of wave action was wanted on the stone to clean away the mud. said Mr Cashin. The mud was being cleared by the dredge but his hope was that

it would be carried away by wave action. Mr Glue said that if the required stone was not available, concrete blocks, which would be more expensive, could be used. < The estimate was that 1400 tons ( of stone would be shifted each i shift. The tonnage was 1600. i If city members were tele- ! phoned when an exceptional ran gfe : was in the harbour, they could < visit Lyttelton, said Mr W. S. Mac Gibbon. 5 - ‘ s