Clyde high dam plans changed

Press, 26 May 1984, Page 8

Clyde high dam plans changed

PA Dunedin The design of the Clyde high dam has been changed to accommodate possible earthquake movement on the fault line running under the middle of the structure. The dam will now have a mobile joint built into it to allow for any movement. It is thought that in an earthquake a small sympathetic movement might occur in the river channel fault, which runs under the dam. Water will be prevented from seeping through the joint by a triangular wedge “plug” extending the full height of the dam, and held in a place by water pressure from Lake Dunstan. The improvement was confirmed by the Ministry of Works and Development’s

project engineer, Mr E. H. Hughes, yesterday. The idea has not been used in New Zealand before, and Mr Hughes said internationally recognised consultants had helped in the proposal. The New Zealand Geological Survey had estimated the probability of fault displacement occurring during the life of the dam as extremely low to very low, Mr Hughes said. “Nevertheless, it is considered prudent to design the dam to behave in a predictable manner, should such fault displacement occur.” The excavation will take about four months and will not interfere with the Zub-lin-Williamson joint venture's concrete placement programme in other areas of the dam.