AUCKLAND'S DRAINAGE

New Zealand Herald, Volume LI, Issue 15563, 21 March 1914, Page 8

AUCKLAND'S DRAINAGE

OPENING NEXT WEDNESDAY. OVER FOUR YEARS' WORK. COST OF ABOUT £450,000. The official opening of the Auckland and Suburban Drainage Board's main drainage works at Orakei will take place on Wednesday afternoon next. The Mayor (Mr. C. J. Parr), as chairman of the Drainage Board, will perform the ceremony, which it is expected will be witnessed by a large number of officials and residents"of the various districts interested. Those taking part in the function will leave the city for Orakei by the ferry steamer Peregrine at 2.15 p.m. The Mayor will turn on the machinery of the detritus chamber. It is expert that a representative of the Government will be present. ' Auckland's new sewerage works constitute the largest single undertaking of the kind ever carried out in New Zealand, and represent a total expenditure of close upon half a million sterling. The total amount available for the work by the raising of loans is £500,000, and_4£? estimated total cost of the whole worn is set down at £450,000. Up to date the amount actually spent is about £370,000. The work was commenced in October, 1909, and the long, and often difficult, construction has gone on steadily since, under the guidance of the Drainage Board's engineer, Mr. W. E. Bush. The total length of the main intercepting sewer, which runs from Orakei to near Cox's Creek, at the boundary between Ponsonby and Grey Lynn, is eight and aquarter miles, and the branches by means of which the system is brought into touch with the spreading of the city and suburbs aggregate another 15 miles. - The reticulation, which is carried out in the various

districts by the respective local bodies, is still in progress, and is not likely to be completed for a long time. The present capacity of the system will serve about 89,000 people, but this total does not re. present the ultimate capacity of the scheme, which is designed for a population of about two hundred and eighty thousand. There are 13 branch sewers serving various suburban districts. One of the most interesting pieces of work in the system is the great storage tank at Orakei. This is a huge triple reservoir of concrete, heavily reinforced. It is 1300 ft. or nearly a quarter of a mile long, and 106 ft wide. The three tanks are about ten feet high, and they have an aggregate capacity of seven and three-quarter million gallons. At the seaward end the chambers communicate by sluices with t)he outfall, bv means of which the contents are led 'into the sea and discharged at a distance of 1213 ft from the shore, and a depth of 30ft below ordinary high water.