WAS RISK TAKEN?

NZ Truth, Issue 1215, 14 March 1929, Page 1

WAS RISK TAKEN?

Burst Reservoir Raises Serious Question

MT. EDEN DISASTER

(From "N.Z. Truth's" Special Auckland Representative.) More by good luck than wise judgment Mt. Eden recently escaped being the scene of a fatal disaster, when the City Council reservoir, which supplies St. Keliers and other areas, burst, and eight hundred thousand estimated gallons of water were released to create desolation and. ruin as it found its own level.

BY a margin of hours many a home escaped bereavement and, possibiy, though this is impossible to state definitely until the .responsibility is allocated, the City Council a huge bill under The Workmen's Compensation Act., • The fact remains that the estimated eight hundred thousand gallons of water chose to select the hour of 5.30 a.m. for its escape rather than during: the hours when the forty odd workmen and casual sightseers might have been on the spot. During working hours there would have been an5 r thing from three to four dozen men m or about the excavation where the new retaining walis were m the. course cf construction. It is necessary to explain the situation to givo a reasonably comprehensive idea of the work m hand. The old reservoir was built m N.N.W. side of Mt. Eden, just above

the drive between Mountain Road and Mt. Eden Road. Being thus built m the concrete retaining walls of the reservoir had the supplementary support of the scoria on all sides. To meet the greater demands on the water supply it had been deemed advisable to enlarge the reservoir's capacity, and to accomplish this it became necessary to excavate the mound to the south side right up to the old reservoir wall. This naturally left the wall minus its former additional buttress of scoria. The walls of the reservoir are about twenty feet high and thirteen inches thick, but reinforced with the usual steel rods. At a seventeen foot level it was estimated by those responsible that there would be one million seven hundred thousand gallons of water within. At the time of the break, the public have been told, there were only eight hundred thousand gallons, or less than half that quantity. The position was then that the south wall was ' asked to take the strain without any auxiliary support of this vast weight of water, and it had not, we venture to say, been built iH IV the expectation of that contingency. ' Last week a small leak was noticed by some of those on the job. There must have been some misgiving as to

the safety of the wall for Mr. W. B. Bush's attention was drawn to it, and the public are told that he issued instructions to. Mr. G. Carr, the waterworks superintendent. In consequence he had a quantity of the water run off, though it has been admitted that at the time of the breakaway there was the amount already mentioned still m the reservoir. Ib follows then that, if the. level of the reservoir was reduced, the thrust was lower than it would ordinarily be, and we believe the thrust of water when so contained is one-third of the distance from the bottom, and yet that thirteeninch wall was not able to stand up to the strain. Very naturally there is one thing which many persons are asking, and that is: What was the drive, thrust, or weight behind that wall while there Was that" thirteen-inch wall suffi-

ciently stout to stand up to such a strain, a strain be it remembered it was never built to withstand, without the natural reinforcement of the scoria which composed the mountain side? It has already been advanced, almost In the form of an apology, or explanation, that In 1912 ferro-concrete work was moro or less m its infancy, or that it has advanced m the last sixteen years. Mr. Bush himself is reported as sayIng that' the break may have been due to structural weakness where the wall joined the floor, or to the excavations for the new reservoir weakening the foundations. It may be asked if this structural weakness was given \the amount of consideration which might have been anticipated, or whether, prior to 5.30 a.m. on Monday morning, the fact that ferro-concrete work was m its infancy was thought to be a good and sufficient reason for taking a risk, combined with the fact that only thirteen inches of "infantile" concrete work stood between forty or more lives which to their owffcers at least had a very considerable value. The impression that remains is that a risk was taken, but why, or . on what really serious reasoning, that risk was permitted to remain has yet io be disclosed.