HARBOUR MOLE

Otago Daily Times, Issue 26273, 3 October 1946, Page 6

HARBOUR MOLE

DAMAGE FROM STORM MAINLY SUPERSTRUCTURE ENGINEERS TO REPORT A decision to obtain from the board’s resident engineer (Mr A. C. Swanson), the consulting engineer (Mr J. McG. Wilkie) and the harbour master (Captain F. G. MacDonald) a report on the damage done to the outer end of the mole by last week’s gale, and recommendations regarding future work to be carried out on the structure, was made at a special meeting of the Otago Harbour Board last night. During the day members took the opportunity to inspect the mole, and the opinion was expressed at the meeting that the damage was much less than had been reported find was confined largely to the superstructure on the outer end. Present at the meeting were—Messrs W. R. Clarke (chairman), W. Begg. S. B. Macdonald, F. E. Tyson, J. G. Jeffery, J. H. Duncan, H. S. Watson. R. S. Thompson and L. F. Evans. Effectiveness Unimpaired The chairman read a report from Mr Swanson, which stated that heavy seas on the night of September 24 completely demolished 293 feet of the timbering at the end of the mole, and damaged four more bays inshore. A recent inspection showed that the stonework at the end of the rriole had been flattened out to some extent, and spread westward, but the general effectiveness of the mole was not impaired to any appreciable extent.

The chairman said the storm haa removed practically two years of the board’s work. The violence of the sea had been such that he did not think any structure within the reasonable limits of the board’s finances could have withstood it.' Breakers 20 feet in height had swept across the end of 1 the mole, and the weight of water pounding on the structure was enormous. Members had seen for themselves the solidarity of the remaining part of the structure, and he was of the opinion that no one was to blame for the damage. It was an act of God.

The board now had to determine whether it would continue with the present method of mole construction or inaugurate some other scheme, such as cutting a channel farther out from the present channel, Mr Clarke said. The events of the past had shown that, while the structure remained, it had fulfilled its purpose, for soundings had shown that the new channel was being scoured out successfully, and depths ranging from 34 feet 6 inches to 50 feet were obtainable at the turn of the tide. Policy For Future “ It would appear that the board will have seriously to consider a new form of structure to withstand the mountainous seas that sweep the end of the mole in bad weather, and decide what policy of replacement it will adopt,” Mr Clarke said, “Looking at it from a practical viewpoint I suggest that the best policy for the present is to consolidate the mole out as far as pile 153, which would bring the stabilised section in line with the easterly weather breaking on Taiaroa Head,. If the board concentrates on building solidly to this point I think it would meet the strongest section of the tide it was trying to divert into the new channel. If any scour is lost the dredge could be equipped for suction dredging to keep the channel in order. I do not suggest that we stop work at bay 153, but that we place that section of the mole in such a condition that nothing will shift it. Then, if it is thought fit, we can work outwards. making x solid structure as we go. From 1925 up to the present the mole has cost the board £170,700, which is an enormous sum to risk being washed away." The chairman repeated that no one was responsible for the damage suffered. The board’s policy relating to the mole had been carried out, but the structure erected on the instructions of the board would not stand lip to the weight of the seas.

Mr Jeffery agreed that the work suggested by the chairman should be done, and said that 4000 feet of the mole were still intact, only the outer 700 feet having been, damaged. A large section of the mole towards the damaged portion could be consolidated without a great deal of expense, but he thought the hoard should obtain a full report from its engineers.

Support for a report by the engineers was given by Messrs Tyson and Thompson, the latter stating that the damage to tne mole, although extensive, could be made too much of. It was not so serious as the press reports stated, for only the superstructure at the end was damaged and the mole itself had not been ’ serious affected. Furthermore no soundings had been taken to determine how much, if any, stone had been displaced. The board had already . spent nearly £171,000 on the mole, and the last 100 feet were the most difficult. In his opinion the board should concentrate on that section and leave the inner portion, which was not endangered, j The mole had provided a good channel ! and had increased the depth from 18 | feet to 34 feet 6 inches, for a width of 1000 feet. He moved that the board’s resident and consulting engineers and the harbour master should be in- 1 structed to compile a report on the | condition of the mole and the steps recommended to effect its completion. “ Tempting 'Father Neptune ” j The motion was seconded by Mr Watson, who said it was satisfactory to know that although the woodwork had been carried away, the stone at the end of the mole was not dislodged to any great extent. The end was expected to do the job of deflecting the tide and that was the pait where more stone should be dumped. The fact that the original mole, which was erected some 40 to 50 years ago. had stood the test and that the present mole had raised the early structure from a halftide wall to a full-tide wall, was mentioned by Mr Begg. “ The raising of the mole was tempting Father Neptune,” he continued, “and he appears to have taken a stand. It is possible that Father Neptune is right and that we have gone far enough, and will continue to get the necessary scour.” The late Captain Mac Lean’s prediction that the mole could not be extended to its present position without suffering damage was referred to by Mr Duncan, who said the board could not afford to continue extending the mole beyond a certain length and having it washed away. So far as the superstructure was concerned, the limit had been reached. Mr Evans said. It had now been washed away for the second time. Mr Macdonald said he was surprised, after reading the press reports, to see what remained of the mole. The press had done the port considerable damage and it was a great pity that the board's executive officers had not been consulted before the reports were published. The press had made a mountain out of a molehill, and after reading the reports he had expected to see the mole smashed to pieces and a danger to navigation. Actually he had found nothing of the sort. The motion was carried unanimously and it was decided that in the meantime the question of interim work on the mole should be left in the hands of the engineers. The report published by the Otago Daily Times last week about the damage to the mole was based on information obtained from the Harbour Board and was in accord with the statement made by the chairman of the board at last night's meeting.