NEW MACHINE FOR DRAINAGE

Press, Volume LXXXIV, Issue 25551, 20 July 1948, Page 4

NEW MACHINE FOR DRAINAGE

UNDERGROUND PLANT FOR DEWATERING FIRST TRIAL TO-DAY A wellpoint dewatering machine, which has been purchased by the Christchurch Drainage Board, will be given its first trial to-day. It is the lirst equipment of its kind in New Zealand. The machine is used principally for withdrawing water from ground in which sewers, pipes, and foundations are to be laid. It may also be used for sinking shallow wells. Its principal advantage is that no soil is displaced when water is withdrawn. The equipment, which is mobile, includes four 20ft pipes, six inches in diameter, each of which has eight small outlet pipes. Lengths of piping with a jet and fine filter at one end are connected to a water-pumping machine, and when the engine is turned on a powerful jet of water shoots from the end, making a small hole down which the pipe drops. The top of the pipe is connected to the outlet pipes, and an engine which creates a vacuum is turned on. Water in the earth is attracted towards the pipes, and the filter prevents any sand or earth from rising with the water. The six-inch pipes are used in the form of a square when a manhole or connexion with another sewer is to be made, but if a long section is to be dug, the four pipes may be joined end to end. ' When the 32 filter pipes are eonnected, the machine can withdraw up to 60,000 gallons of water an hour. A pressure of between 200 and 250 pounds is needed to put the jet pipes down. The machine is being operated by Messrs Frank and Tom Greenhalgh. of Manchester. England, who have had considerable experience with similar equipment in the United Kingdom. Wishing to emigrate to New Zealand, they noted the address on one of the machines they packed, and wrote to the agents in New Zealand, asking for the position of operators. The agents forwarded the letter to the board with the machine, and the board was able to obtain a priority for the two men. They said yesterday that there were only about 30 similar machines in the United Kingdom, one in Persia, and another in India.

The machine will be used to-day at the corner of Galbraith avenue and Avonside drive, where the board is putting in a manhole for the Christchurch City Council.