HALF-A-CENTURY

Evening Post, Volume CXXV, Issue 145, 22 June 1938, Page 13

HALF-A-CENTURY

24-INCH WATER MAIN

TRICKY REPAIR WORK

It is unfortunate, but water mains, which cost a lot. of money, do not last for ever. The_24-ihch cast-iron main which every* so often springs a leak or bursts and smashes the bitumen surface of the Hutt Hoad has given remarkable service to Wellington, for it was laid over 50 years ago, in. or about 1880. It will last for more years yet, but only at the expense and trouble of repairs. \' From the Wainui reservoir a 30-inch cast-iron main'leads to the Pipe Bridge over the Hutt Rivst but there it splits - into 24-inch IBff 21-inch mains, a 30-inch majttWjw just about the carrying HMelßf of the two" smaller mains. of 24inch main under the Pipe Bndge is in steel, not cast-iron, and steel has not the long life of cast-iron under normal conditions.

It became apparent some years ago that this length would have to be renewed, but it has carried on till, now without giving trouble. The pipes themselves are generally sound, hut the joints, exposed to the action of sea air arid spray in bad weather, Save gradually lost v their protective bitumen sealing, and "corrosion has increased and threatened trouble.

The pipes are carried on concrete piers underneath the bridge decking and there was a'fair amount of working space when the 24- and 21-inch mains were laid, the laying of a third main (the 21-inch steel high-pressure main from Ofongorongo to Karori) has taken up all but a few feet of space. Consequently the renewal of the old 24-inch main is a far more difncutf piece of work than a straight-outlay-ing of a new main would be. Special bends had to be devised to sidetrack the water, and as each joint is broken the pipe lengths have to be jockeyed out along a narrow way, between the bridge structure and over the other mains. The lengths are heavy, and the going is awkward. The city supply will not be affected, for at this time of the year there is ample capacity in the remaining mains. In any event, the artesian supply, on the city side of the bridge, could be called on if necessary.