WATER SUPPLY

Te Awamutu Courier, Volume 59, Issue 4186, 15 September 1939, Page 5

WATER SUPPLY

MORE ABOUT THAT TUNNEL. A VISIT OF INSPECTION. “NOT SO BAD AFTER ALL.” Some concern, not to say alarm, was occasioned among residents who take an interest in such things when the borough engineer, Mr Ralph P. Worley, reported to the Borough Council meeting on Monday evening of last week that there was real need for extensive improvements to the municipal water service, notably for the expenditure of a considerable sum of money on concreting the large tunnel on the route of the water-pipe line from Pirongia mountain. All sorts of assumptions were made, and with a view to getting first-hand information a representative of Te Awamutu Courier arranged for a visit of inspection. This was made yesterday morning, in the company of Crs W. J. North and C. J. Spiers (members of the works committee) and Mr R. H. Close (the works foreman). The first place of importance visited was the lower end of the large tunnel that was made four or five years ago to convey the water by a more direct route from the dam at the intake to the foot of the hill. This tunnel, by the way, was the subject of deliberation and discussion at Council meetings at the time, and it was eventually sanctioned.

ENTRANCE CAVED IN. The latest report showed that both entrances had caved in, and there were indications that subsidences had occurred at places inside the tunnel. Further, a good deal of water was running to waste, presumably as a result of damage done to the pipeline inside the tunnel. The amount of water issuing from the tunnel had been measured and computed to be approximately 100,000 gallons each 24 hours. That, of course, represented a very serious position; but ’ borough workmen have been making a closer acquaintance with the position, and Mr Close found that the Te Awamutu end of the tunnel had became blocked by detritus that had fallen from overhead. The outlet from the tunnel had never been protected beyond using a few poles and props, and the recent persistent rains seem to have so soaked the ground that it slipped into the cut leading to the actual tunnel. One big stump of a tree right above the tunnel entrance came down on to the pipe-line, and this, according to Ml* Close, was the prime cause of the leaks in the pipe, for the fall had caused the lead joints to “ spring,” and the w’ater squirted out. There were two joints leaking, so the workmen effectively plugged them; and then a fresh measurement was taken. There was very little diminution in the quantity of w'ater from the tunnel mouth ! Clearly there were more leaks further inside or there was a persistent seepage from the surrounding terrain. An inspection within the tunnel was quite convincing—there was no other leak so far as the inspection proceeded. But there was a persistent seepage that was not affected by the cutting off of the water passing through the pipes from higher up the line. Thus the seepage was the prime cause of the outflow’ stream that, when measured, wras in the neighbourhood of 100,000 gallons per 24 hours.

ALTERNATIVE ROUTE. The visitors were all keenly interested, and when the tunnel had been inspected the engineer’s proposed alternative route, involving a new pipeline for about half a mile, was inspected. This would avoid the big tunnel—in fact, it w’ould make that expensive adjunct to a good water service useless—and carry the water round the brow’ of a hill instead of cutting through it. But the engineer estimated that the diversion would cost something like £2400. Opinions on the subject may differ, but there seems good ground for the contention that the present large tunnel, some

880 feet in length, could be concreted for less than that figure—probably a good deal less. That concrete would mean that the pipe-line would always be available fen* inspection, for it would prevent any cave-ins. The point to be decided by the Borough Council, in its wisdom, is whether the diversion tunnel should be made at a cost of about £2400 or the tunnel should be concreted for its full length at a cost estimated to be from £l5OO to £lBOO. AT THE INTAKE. The dam at the intake much higher up the slopes was next inspected, and here it was evident that a good job had been made of the scheme, although there is an accumulation of silt several feet deep that will need removing.

Asked w’hat his plans were, Mr Close said he would like to see the dam raised about seven or eight feet —the latter height preferred—with a concrete retaining vrall on one side of the stream, for a few’ feet, and a wing on the far side of the stream, to get the full advantage of the increased height of the dam. That would provide millions of gallons of water in the impounding basin—much more than sufficient to keep the whole Te A*wamutu and the surrounding farming areas supplied with an adequate supply of water during the longest spell of dry weather, for, be it remembered, there is a fine stream of water running into the reservoirdam all the time.

It would seem to the layman that to improve the impounding basin would be preferable to erecting a reservoir or w’ater tower closer to the borough. The cost would be smaller, the pressure of water would be greater, and there could be little chance of a break or a blow-out along the line that would cut off supplies in time of need—ifor instance, during an outbreak of fire in the town requiring a large supply of water to check it. Raising the level. It is to be noted that Mr Worley has reported on the scheme for rais-

ing the level of the dam. He gives the approximate figure as £l2OO. Mr [Close told us that the original dam cost about £7OO, and the foundations were over 20 feet below ground level. If he and his men did the existing job for about £7OO it would seem that the engineer’s estimate of £l2OO is ample for the additional work. Maybe the cost w’ould be less—ibut also maybe it will be more. Mr Worley said the additional storage would probably be in the vicinity of 1,000,000 gallons of water. If he intends to raise the height of the present dam by eight feet it seems fairly reasonable to estimate that his figure as to quantity is on the conservative side—-very much so. The configuration of the country shows that to raise the dam wall by 8 feet would increase the impounding area by more than double its present size, and give a depth of water more than double what it is in any but a small portion of it. However, Mr Worley has seemingly not made a thorough inspection of the main points of the scheme for providing Te Awamutu with an adequate supply of water for the whole 24 hours of each day of the year. He has a great deal of technical knowledge denied the layman, and perhaps, if and when asked for a report, he will tell the Borough Council what is best for them and the people they represent, having, at the same time, a due regard to the cost. That is important. There must be a feeling amiong those who, as ratepayers, provide the money that a good deal too much has already been expended by successive Borough Councils in providing the town with “the best w’ater supply in any part of the province,” as someone once said.

GO AND SEE FOR YOURSELF ! No doubt the matter will come before the next meeting of the Borough Council, with appropriate reference to the subject from the works committee and the finance committee. Meantime we would strongly urge upon councillors to at least make themselves familiar with the basis of the scheme by each making a personal inspection of the locality, under the guidance of either the works foreman (Mir Close) or the chairman of the works committee (Cr W. J. North), who has closely identified himself with w’ork on the slopes of Pirongia over a period of years. We have in mind the admission of several former councillors who had never been up there; yet they were prepared to debate any water-works proposal placed before the Council. They owe it to the ratepayers to inform themselves.