PETONE'S WATER

Evening Post, Volume CIX, Issue 116, 19 May 1930, Page 12

PETONE'S WATER

THE NEW WELLS

STREET MAINS AND PUMPS

AMPLE SUPPLIES

Water! The topic of the day! Wellington, Petone, Lower Hutt, Upper Hutt, Eastbourne, are all in various stages of agreement or disagreement regarding the best way of securing this indispensable element for themselves. The following article describes Petone's water supply, its sources, and the means of its conveyance to the taps of the 12,000 inhabitants of the borough.

As far as the existence of a water supply is concerned, Petone has never had any trouble, for there is plenty of water Available from two excellent sources, the Korokoro dam iv the hills to the west of the borough and seven artesian ,wells near the Hutt River in the eastern part of the borough. The Korokoro dam, which is over 200 feet above the level of the town, has a capacity of 8,000,000 gallons, and is served by a catchment area of some 2000 acres. From this reservoir the average quantity of water available per day is 600,000 gallons, while the artesian bores can give over 4.00,000 gallons per day. The total supply available is thercforo approximately 1,000,000 gallons per day, of which it is estimated that 505,000 gallons per day in winter and 770,000 gallons per day in summer are used. It is clear that the water is there, though the pressure may not be. The real trouble has been in the inadequacy of the means of conveying the water to the peopie at a good pressure. Until recent months the water-mains in the borough were far too small to serve their purpose efficiently. This was partly due to the greater draw-off consequent upon the increase in the population of the borough, and was a thing only to be expected. A more serious factor in the weakening of the pressure was the incrustation of the insides of the mains. This coating was in places about three-quarters of an inch think, so that what began as q. 6-inch pipe, for example, had, after its many years of use only a 4J-inch waterway. Similarly, a 3-inch pipe would have an effective diameter" of only li inches. The loss of pressure caused by/ this reduction in bore was at its least an inconvenience to the householder and at its most a serious handicap in case of fire, as the Petone Fire Brigade found more than once. ENGINEER'S REPORT. What was needed to ensure a 'good pressure was a new and an addition to the source of supply. Recommendations to this effect were made by Mr. 11. Vickerman in a report presented to the Petone Borough Council in the middle of 1927. He, suggested three means of obtaining an increased supply: the "raising of the Korokoro dam, the sinking of more wells, or the obtaining of water i'roin the Akatarawa River. In , any case the renewal of the borough reticulation wouM be essential. The supply from Akatarawa was recommended in the following terms:—''For the general good of the district, and because its present demand for water must double with the growth of population, it would appear inevitable that Petoue, alon^ with the neighbouring boroughs, must eventually become party to a scheme for a general supply from'Akatarawa." The discussions on the subject at Water Board and local body meetings are well known, as is also the fact that Petone and Lower Hutt eventually withdrew from the Water Board, each preferring its own supply to the prob-lematical-good of Akatarawa. \ ■ Meanwhile, the Petone Borough Council decided to reticulate the borough afresh. A £60,000 loan proposal for this purpose was submitted" to the ratepayers and passed. The Loans Board having stipulated that '-he work should be done by instalments, one-third of the borough was reticulated. This having been done with very satisfactory results, the Loans Board sanctioned the rest of the work, upon which the contractor (Mr. J. Avenell) is at present engaged. ...

ARTESIAN WELLS,

Of the three sources of additional supply recommended by Mr, • Vickerinan; the council chose the artesian vrells. Four new 6-inch bores were sunk and proved au unqualified success. They are close to the seven old 3-inch wells in Tennyson street, near the river, and lie in an cast-west line some 15 feet apart. Eaelr new well has a flow of approximately 600 gallons of water per minute, so .that the four together can give 3,456,000 gallons per day, which is seven times as great as the output of the seven old wells. With the present summer consumption of 770,000 gallons per day, it will be readily seen what an enormous quantity of spare water is available from the new wells, and, in. addition, there are the old wells and the Eoro Koro reservoir, supplying 1,000,000 gallons per day. Little wonder that the new bores have impressed the Mayor and borough engineer of Lower Hutt and City Engineer. ■ Whence comes this water? ; One hundred feet, below the surface, below sand, silt, and mud, is a stratum of big shingle from which the water flows. The Petone Borough Engineer (Mr. C. L. Jackson) has a theory that this stratum extends northwards in an upward sloping'direction along the Hutt Valley, and that eventually it crops out into the bed of the- Hutt. Kivor. The river water drains down into the outcrop and runs along the shingle bed, a, sort of lower story of the Hutt River, to where it is topped by Pctone'a artesian wells. There is no proof for this assumption, as a complete geological survey has not been made in the Hutt Valley, but it is borne out by the facts that there is a large outflow of fresh water from the bed of the harbour near Somes Island and that a flow of fresh water was'tapped by the piledrivers for the wharf off Point Howard.

If Petone wants more water it is only necessary to put down more wells and the water will come. Judging from the quantity the wells are now giving and from other indications, including the fact that the boring of the new wells, made .*ot the slightest difference in tbe flow from the old ones, the supply from the underground river ia practically unlimited. There is an opening for Eastbourne here, for if they can tap the stratum near Point Howard it would be easy to pump the water round the bays.

THE PUMPING SYSTEM.

The water in the artesian bores rises tun feet above ground level and is led off to fill a largo tank to the same height. From the tauk it is pumped to the mains at a pressure o£ 65 pounds per square inch. The two pumps at present in use are operated electrically and have a total capacity of 720,000 gallons per day. The pumps do not operate continuously, but are switched on by the power station fjltendants when the pressure in the main falls below 50 pounds, which is considered sit'lequate for household- purposes. For fire lighting a pressure of'6o to 300 pounds is needed, and to get this pressure at short notice the fire alarm automatically switches on one of the pumps. The other is switched on manually as soon, as possible. During the

night, when there is very little drawoff, tho pumps are not needed (except in case of fire) and the borough is supplied solely by gravity from Koro Koro. Tho council has obtained a now and larger electric pump which can deliver into the mains 2,016,000 gallons per day at a pressure of 86 pounds. This will be in commission by next summer. With a horsepower of 200 as against 19 and 21 of the two pumps now in use, its running expenses are exceedingly high, and as its use continuously would not be warranted it is to be kept as a standby, to be used in case of lire or in the unlikely event of the Koro Koro reservoir being unable to maintain pressure. When the reticulation of the borough is completely r.enowed, which should be in the early months of next year, it is possible that the hours of pumping may be reduced without causing any loss of pressure. A LOT GAINED. Mr. Vickerman, in his report, sets forth tho desiderata as follow: "It is evident that, apart from allowing for tho future growth in demand, any new supply should be capable of delivering 2000 gallons per minute, and this should bo at such a pressure that the losses in the reticulation system will not reduce the pressure to much, if anything, below 60 pounds per square inch." With the now reticulation, the Koro Koro reservoir, the old Wells, and the new wells, and the pumps this can be done easily. Scv'that for £60,000, the total cost of the reticulation, the new wells and tho new pump, Petono will have gained for itself a more than adequate water supply for years _ to come and full pressure for fire fighting. O,ue thing in Mr. Vickerman'a report has not been yet dealt with —the supply to Koro Koro residents. . Living, as it wore, next door to the reservoir, they cannot be supplied from.it by gravitation, and the only plan recommended was to build another reservoir at a commanding level and to pump water up to it, an expensive job. So far tho council has done nothing in this matter.