ARTESIAN WATER

Dominion, Volume 32, Issue 146, 16 March 1939, Page 11

ARTESIAN WATER

Gear Island Plant In Operation AUXILIARY SUPPLY Three Million Gallons A Day Drawn Off ■‘T think we should congratulate the engineers who put in the auxiliary plant at Gear Island. I his has saved the city a capital expenditure of more than £100,000,” said Cr. W. Appleton, chairman of the works committee, at last night’s meeting of the Wellington City Council when consideration was being given to a report from the city engineer, Mr. K. E. Luke, on Wellington's water supply. Ihe artesian plant had been drawn on to the extent of 3.000,000 gallons a day, which had enabled the city not only to bold its own but to build up a reserve in the city reservoirs, said Cr. Appleton. The mayor, Mr. T. C. A. Hislop, referring to artesian development, said he well remembered the battle there had been a few years ago. There had been considerable opposition to the Gear Island scheme on the ground that the water would be unhealthy and that it would not prove equal to the requirements. He himself had been in favour of the proposal and "the proof of the pudding was in the eating.” When the water had been brought in, it bad been carefully analyzed and found to be perfectly pure. ‘‘The whole scheme cost £16,000. less than one year’s interest and sinking fund on the other scheme advocated.” said the mayor. •‘This scheme will definitely keep us going for some time ahead. It was a good thing when the rain fell because that saved us the cost of pumping, but if there had .been no rain, there would have been ample water from the artesian supply.” It was the first time that the city had had to draw on Gear Island to any extent, said the mayor. After the opening of the scheme, Gear Island had been drawn on to a certain extent, but only to test the pumps;. The scheme had answered all tests satisfactorily and there had been no fall in the level of the artesian well. Cr. L. McKenzie said he had heard several comments on the very marked improvement in the quality of the water. „ . Cr Chapman. M.P.: '1 he report shows that 100,000.000 gallons a year are available. Surely we could make greater use of it. The mayor said that the question of alteration to the pumping plant could be considered at a later date.

Engineer’s Report.

The city engineer's report, dated March 9—before the .shortage had been relieved bv a fall of rain—stated:— ’ “There has been no ram tn the watersheds since the Christinas holidays, and heavy continuous northerly winds have been followed by extremely hot weather. This has had a severe effect on the stream flows at both Wainui and Orongorongo. “The upper Karori reservoir was put into operation on January 26, and at the present time is two-thirds depleted. Storage at Wainui was drawn on on February 17. On March 2 the Morton dam had dropped more than 3ft., and the lower Karori reservoir more than 4ft., the drawoff from the Wainui and Orongorongo mains averaging at that time about 9,500,000 gallons a day. The auxiliary supply from Gear Island was thrown into operation on March 3. and had the effect of arresting the draw-down in the reservoirs. Since that date, some of the storage in the lower Karori reservoir ami the Morton dam has been recovered, and the draw-off on the Wainui and Orongorongo mains has been reduced in volume from 9,500,000 to under 6,000.000 gallons a day. The auxiliary supply has been running continuously and is delivering into the city a quantity, of water between 3,000,000 and 3,500,000 gallons a day. “In view of the uncertainty as to the length of the dry weather period, and also because of the cost involved in pumping, steps have been t to restrict h etakenrf steps have been taken to restrict the illegal use of water and also waste, night inspection being carried out by inspectors.

“Regular analyses of all sources of supply have been carried out by tire department’s chemist. The exposure of mud deposits in the Wainui reservoir has accelerated the growth of elementary life, and steps have been taken to counteract this. It would appear also that following the heavy rainfalls of last winter the <siltation of this reservoir has increased and a check survey of the impounding capacity is now. being carried out. ’The analyses of the artesian water show this to be of a consistently high quality.”