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WATER BREAK 'COULD NOT BE FORESEEN' The break which had occurred in the open concrete water channel from Canning Dam to Perth could not have been foreseen and no blame was attabhable to anyone, the Minister for Works (Mr. Doney) said yesterday.
Mr. Doney said that the only feasible method of closing the gap was to lay twin 30in. pipes across the break. This work was completed a week after the break occurred, although water had been passing through the pipes in increasing quanti ties for three days before the job was completed. It was impracticable to reconstruct the channel and permanent repairs must be done with the use of a pipeline syphon. Steps were n hand to have a survey made and a design prepared to ea able permanent repairs to be carried out soon. All the men engaged in the work were to be congratulated on the speed with which the repairs were effected in difficult circumstances, he said. The channel at either side of the break was in first-class condi tion. No trouble of this na ture had been experienced since the channel was completed 13 years ago. "Inevitable Delay" The. channel was regularly in spected and patrolled, Mr. Doney said. It was nine miles long and some delay was in evitable . before' either the patroller or a passing motorist could report a break, or the maintenance man at the pipe head at the lower end of the channel would be aware that the flow was falling off. It would be about four hours before, the. fall of the level in the channel that would- result from a break could be noticed at the pipe head at Gosnells. As the escaping water had washed out a large area of the hillside, it had been impossible to ascertain the cause of the channel breach. An examina tion .of the area indicated that the trouble probably originated either from a landslide below the channel or from damage to the channel bank by the falling of a large redgum tree. To meet emergencies of this nature and to provide for varia
tions of supply, adequate ser vice-reservoir capacity was es sential in any city system that depended for its supply on long trunk conduits from hills stor age reservoirs. The recognised safe practice by water supply authorities was a capacity equal to three days' maximum con sumption. First-Priority Work During the war it-was im possible to carry out any major work', Mr. Doney said, but the extension of .the second trunk main orom Cannington to Mt. Yokine and the con struction of additional service reservoirs at Mt. Yokine were made the first priority in post war work. Work on the first of four reservoirs, each with a capacity of 30,000,000 gal lons, was nearing completion at Mt. Yokine and the excavation for the second reservoir in the series was well advanced. Had normal deliveries of material come forward, the first reser voir would have been in opera tion this summer. Mr. Doney .said that for seven days before the break, occurred, water consumption in the metropolitan area had exceeded the total output from the hills and bores. This had reduced the total quantity of . wates available .in the service reser voirs, but not to any abnormal extent. Service reservoir stor ages .were considerably depleted when the flow of. the channel ceased and before the :full bene fit of a reduction in consump tion due to the water restric tions could be secured. Be fore the restrictions were re laxed, it was essential. to restore the storage in the reservoirs to a normal quantity. Officers of the department were fully aware of the great necessity for expansion of the supply system to cope with a rapidly increasing demand brought about by the building programme. No stone was be mg left untmirned in making progress with the .necessary works, despite the difficulties in obtaining materials.