DRAINAGE BOARD PLANS

Press, Volume LXXXVII, Issue 26559, 23 October 1951, Page 8

DRAINAGE BOARD PLANS

SEWERAGE SYSTEM IN

NEW MAIN PUMPING STATION

Preliminary planning for the construction of a new sewage pumping station at the eastern end of Woodham road, which will ultimately become the principal station for the greater part of the Christchurch Drainage Board’s area, has now been started by the board’s chief engineer (Mr E. F. Scott) and his staff. This new station will be 8000 ft nearer the sewage treatment works at Bromley than the present main station in Tuam street, which has been operating for 69 years. Eventually the Tuam street station will cease to function and will become the board’s principal maintenance and stores depot. The plans on which the board’s engineers have started also provide for new sewage treatment works to deal with the increased quantities of sewage that will have to be handled in future, a relief sewer to serve the northern area, and the extension of the Tuam street sewer as a gravity main along Ollivier’s road and Worcester street to the Woodham road station. When the whole scheme is completed the main northern and southern sewers will rim in parallel along Woodham road eastward from Worcester street and will be inter-connected to give flexibility to the system. All these works will not be covered by the loan of £425,000 for which the board obtained authority last year under a Board of Health requisition. A further loan proposal will have to be put forward to finance the work on the northern relief sewer, the completion of the new pumping station, and the new sewage treatment works. In its planning the board is providing for anticipated development at least 50 years ahead. The supply of labour and materials is the critical factor in the execution of the board’s big scheme, but the work is being pressed on as fast as possible, in spite of staff difficulties, as the board realises that it is essential as a prerequisite to the extension of the sewer reticulation system to serve the increasing housing development in the suburban areas of Christchurch. Choice of Site Mr Scott explained that the choice of Woodham road as the site for the new pumping station had been dictated by the plans for the northern relief sewer which traversed Bealey avenue and then went eastward along Woodham road. The equipment at the station would include six pumping units each capable of handling 6000 gallons of sewage a minute ana discharging through three parallel 36in diameter pumping mains to the sewage treatment works on the sewage farm reserve. Provision would also be made for a large M.E.D. sub-station and a standby plant to generate enough power to keep the sewage moving in periods of sudden power failure. The extension of the Tuam street sewer as a gravity main will be carried out entirely with the board's well-point equipment because of the nature of the ground through which it will pass. Mr Scott said that had such equipment been available in 1880 for work in heavily watered ground it was quite probable that the present Tuam street station would have betn built somewhere in the locality now proposed for the new pumping station. Reviewing the board’s present sewerage works and those projected, Mr Scott said that the expansion of Christchurch and increased housing development had brought the board a huge number of problems. The existing sewerage system had been severely ■ taxed. In the war years the number of sewer connexions had increased from 30,000 to 35,000, and 54 per cent, of this expansion had been in the Riccarton area. As a result the board had been forced to remodel the existing system of main sewers to meet the immediate and future needs. Mr Scott said that the most urgent task had been the provision of a southern relief sewer to take the increased flow from the Riccarton area. The loan of £60,000 authorised in 1947 had provided for work at the sewage farm and enabled the board to make a start on the first section of the relief sewer—the portion between Fitzgerald avenue and the discharge point of the Riccarton pumping station. A 43in main had been carried along St Asaph street as far as Colombo street When authority was obtained for the loan of £425,000 provision was made for carrying the 43in line from Colombo street to Deans avenue. The contract for the first part win be carried out by B. Moore and Sons, Ltd., and work will start shortly. Work on the second part for which the W. Williamson Construction Company, Ltd., has the contract has now started. Northern Sewer Mr Scott said the board was now planning for the extension of the main line from Deans avenue through to Division street and a branch line up Division street to Riccarton road to intercept the sewerage of southern Riccarton and bring it by gravity down the new southern relief sewer. The loan also provided for the duplication of the main Tuam street sewer between the pumping station and Fitzgerald avenue by a new 48in gravity main along St. Asaph street eastward from Fitzgerald avenue to the station. Provision had been also made for alterations to the putnping station and a new rising mam' to the treatment Not included in the present loan proposals, but still urgently necessary, according to Mr Scott, is the relief of the northern sewer, particularly the St Albans and Merivale section. The boards plans also envisage ultimate extension to Strowan road to intercept a big portion of the Fendalton sewerage and the continuation of the line as a main sewer up Wairakei road to meet anticipated development in the north-west area. Mr Scott said that during the war years several small works had been earned, out to relieve the sewerage position, particularly in the Riccarton area, but the board realised that as •oon as staff and materials were available it would be faced with these major works which involved a complete remodelling of the trunk sewer system. TOese works were designed to meet the. immediate and future needs of Christchurch.