COMPLETION OF THE WATERWORKS.

Taranaki Herald, Volume XXXI, Issue 4285, 8 March 1883, Page 2

COMPLETION OF THE WATERWORKS.

Yesterday His Worship tho Mayor and Membeis of the Borough Council, accompanied by Mr. Barr, C.E., and Messrs. Henderson, Mackay, and Fergus, the contractors, visited the Waterworks for the purpose of inspecting the machinery, and the manner in which the pumping operations were being carried out. On arrival at the reservoir it was found that the water was flowing in from one of the pipes at the rate o£ '256 gallons per minute. The party then proceeded to tho engine house, where one turbine and force pump were at work. The pumping machinery consists of two turbines and pumps capable of raising 500 gallons per minute, and forcing it up into the reservoir. Both turbines were at work during the morning, but the belt wheel attached to one of the turbines broke, probably on account of being damaged while on board ship. With the exception of this accident, the machinery was working satisfactorily. Of course where now machinery is just started, it is neces sarily stiff in working, necessitating several minor alterations ; but these, we understand, will not be of any consequence, and on the whole the machinery may be said to be in good working order. One engine is of itself more than sufficient to keep up the supply of water for tho town at present, and therefore, when an accident happens to one of the pumps, it will not interfere with tho water supply. It was found necessary to erecftwo air-valves on the top of the hill, where the difference in the grade of the service pipes occurs, so as to prevent the concussion of air in the pipes. The reservoir can be filled in fortyfive hours when both pumps are working, and it is estimated that when the reservoir is full it will supply the town for about a fortnight, if necessary, without any further pumping operations.

The point on the river at which the dam is constructed is unusually wide, and it has been found necessary to depart somewhat from the original plan for the dam, owing to the large volume of water which courses down the river during a heavy " fresh." The dam has been made stronger than originally designed. It is four feet in height, but it will be raised six inches higher in order to provide an adequate supply of water when the volume of water in the river is at its lowest. The head r.ieo is 1700 feet in length, 8 feat wide, and 4 feet deep. The entrance to the head race, which is on the bank of the river, is made of solid concrete, and is 12 feet wide, having two separate rows of iron gratings to prevent the drift wood entering the race from the dam. About 20 feet from the gratings are situated the ilood gates, which form part of the entrance to the race. The head race is in the form of a crescent, and is also made of concrete, with turf banks on each side, preventing the accumulation of debris of any kind in the race, anil forming a complete protection should the river at any time overflow. The floor and sides of the race have been made of the best concrete, and have" 4 a clean, finished appearance. The race is continued along the bank of the river until it reaches a point immediately below tho reservoir, where the pumping machinery is erected. The water ilowina: along the race from the dam empties itself into the pump well and also into the turbine pipes. The pump well is five feet deep and six feet in diameter, and into it are placed two suction pipes, being part of the pumping machinery, through which tho water is drawn from the well and forced up through the pipes into the reservoir above. The pumps are double-acting force pumps, and are worked by two reaction turbines, about 13^ bojse power, each performing from 95 to 100 revolutions per minute. The fall of the water down the turbine pipes is about 12 feet, the pipes being 26in. in diameter, so that ample motive power is procured for the turbines, which are compact machines, about four feet in diameter. A tail race is constructed for carrying the waste water into the river. At the end of the race a contrivance is fixed which regulates tho flow of water, so that the race will not have more than fifteen inches of water in it unless it is necessary to alter it, when the volume can be increased. The castings and shafts are excellent, and the whole machinery has been fitted up with exactness and care. Ascending a long and steep ladder from the pumping machinery, communication is had with the reservoir, which is situated at the top of the hill. Pipes are laid up the hill, through which the water is pumped up to the reservoir, which is a circular basin made of concrete, 210 feet in diameter, and 13 feet deep. It is " rounded up" with turf banks, which prevent any surface water, being drained into it. A. massive concrete structure called the valve-tower is built in the basin. The front of this structure is perforated with holes about two inches squire, to admit the passage of the water from the reservoir into the service pipes. A quantity of gravel is placed in front of these holes, through which the water is filtered before it is received into tho valve tower. Every precaution has been taken in connection with tho reservoir to ensure the purity of the water supply, and as the arrangements in this respect are admirable, the supply of water laid on to the town cannot be surpassed. It will, no doubt, be ( a great blessing to the inhabitants of New Plymouth ; and in future years, when the town has grown larger, it will probably be more appreciated than at the present time. The cost of working the machinery is very small, and the supply of water will always beudequate. The work has been carried out in a most substantial manner by the contractors' — Messrs. Henderson, Fergus, and Mackay, of Dunedin. They have experienced many difficulties in connection with the execution of the work, and their practical experience lias enabled them to make valuablo suggestions for the purpose of strengthening various portions of the work, particularly the dam. The design of the waterworks is by Messrs. Barr & Oliver, Civil Engineers, of Dunedin.

The minor alterations required will probably take about a fortnight before they are completed. According to the terms of the contract the contractors aro required to keep the works in repair until three months after their completion.