WATER TUNNEL

Northern Advocate, 29 October 1932, Page 14

WATER TUNNEL

BIGGEST IN AUSTRALIA.

LIFE UNDERGROUND

MEN AND PONIES AT WORK,

SYDNEY, October 12,

Three hundred feet below the ground, between Potts Hill and Ashfield, is a scene of considerable activity: Nearly 300 men are working day and night to complete an engineering task of great magnitude, which will increase materially the efficiency of the metropolitan water supply. The work consists of lining with gigantic steel tubes the high pressure water tuuncl which was constructed a few years ago by the Water and Sewerage Board to bring supply from Prospect reservoir to a station at Waterloo, from where it is pumped to the city. The tunnel is the largest of its kind in Australia, and among the largest in the world. Par Below Surface. Descending in a typical mining cage far below the level of normal life, the visitor reaches a cavity lighted by electricity, whore workmen are waiting to receive constructional material from the, shaft head. Great steel tubes, each weighing three tons, Bft in diameter and fift long, arc brought down from the surface by moans of special lifting plant, and placed at the shaft bottom, ready for moving into position, perhaps a mile or two miles along the tunnel. Diminutive and well-trained pit pones drag lines of sand-filled buckets along an overhead railway running the length of the tunnel sections, and push the steel tubes on a special trolly from the

shaft to the “faces,” where the workmen are engaged, these tubes are worked into position on adjustable and spring jacks; “spiders,” or spreaders, arc employed like the spokes of a cart rvheel to maintain the rigidity of the tubes (unsupported, they sag nearly two inches), and men ram them together in the glare of electric lights. The walls of the steel tunnel, dazzlingly brilliant and reflecting a line of hundreds of electric, globes, fade away to infinity. Eight-Hour Shifts. At frequent intervals workmen, sweating and straining at their task of working the tubes so that they join with the next, break off to communicate with officers at the shaft head and at other points by telephone, which is laid to the working positions. The sound of concrete mixers reverberates for the tunnel’s length. Ordinary conversation carries for an astonishing distance —voices that appear to be a few feet away may quite possibly be uttered so far off that the speakers cannot be seen. An explosion of magnesium powder, for photographic purposes, was hoard more than a mile along the barrel of concrete and steel. The 280 men employed spend 24 hours underground in three eight-hour shifts. The ponies also have their definite shifts, usually numbering the same as those for the men. Except for the shaft head and cage winding-gear there is little on the surface to indicate the presence of an active community below, engaged day in and day out, on what is undoubtedly the most outstanding water supply work that has been undertaken in Australia. Progress of Work. Excellent progress is being made with the work, which constitutes the

most important part of the Water Board’s employment relief programme. An average of three steel tubes are plaeed in position each day. The tubes are being manufactured by Australian Iron and Steel, Ltd., and nearly 2000 of them will be neeessary to complete the work.

Excavation of the tunnel began in 1929. It was constructed of concrete through Hawkesbury sandstone, and was 10ft in diameter, being completed in 1929. Owing chiefly to the fact that the work was something of an experiment, and also to the failure of the sandstone in which it was embedded to withstand the great pressure exerted b% r the water, the concrete lining in 1990 developed faults, and the tunnel could not be brought into effective u&.

Thn present programme of the board provides for relining the whole length with steel. Actually what is being done is to construct a steel tunnel inside the original concrete one, the new one having a diameter of a little over eight feet, or two feet less than before. An expenditure of £230,000 on lining the tunnel to the No. 0 shaft at Enfield has been authorised by the State Government, and the Water Board is hopeful of getting additional funds to permit of the completion of the full work. It will substitute the existing system of mains from Botts Hills, which, It is stated, are approaching a stage when replacement would be necessary.