AUCKLAND DRAINAGE.

Auckland Star, Volume LXII, Issue 202, 27 August 1931, Page 3

AUCKLAND DRAINAGE.

COMPREHENSIVE SCHEME.

SEWERAGE AND STORM WATER.

PROVISION FOR WIDE AREA,

Some indication of the scope and nature of a comprehensive sewerage and storm Avater drainage scheme, which is being the Auckland metropolitan district, was given in an interim report presented to last evening's meeting of the Auckland and Suburban Drainage Board by the engineer (Mr. H. H. Watkins).

Since investigating modern drainage systems abroad some time ago, Mr. Watkins had been inquiring into local conditions. The need for a major scheme for the city and suburbs has been raised liy the Health Department and the Auckland Harbour Board, both of which have been concerned over the increasing discharge of sewage into the Waitemata and Manukau Harbours at a number of different points. Area Embraced By Scheme. The area • which will be embraced by the scheme will comprise the city of Auckland, eleven boroughs (including those of Devonport, Takapuna, Northcote and Birkenhead), three road districts, and four town districts, the total area, of which is 79.5 square miles. Tho territory concerned has a population of 212,210, and a rateable value of £80,607,948. The present drainage district consists of portion of Auckland city, the whole of Mount Eden, Mount Albert and Newmarket; and portion of One Tree Hill and Mount Roskill, and serves a population of 155,500.

Mr. Watkins explained that his investigations of the larger district, and of the drainage systems already installed, were practically concluded, and he was now devoting his undivided attention to the preparation of his report. This would be comprised of the following principal sections: —(a) A general review of all existing drainage systems in the metropolitan district; (b) particulars of the observations made by him during his extended tour abroad; (c) statistical tables and graphs; (d) proposals and recommendations for the constitution and administration of a metropolitan drainage district; (e) alternative projects for incorporation in a scheme of sewerage and storm water drainage for the district; (f) financial considerations. A Complex Problem. "It will be understood that the problem with which I am concerned is an exceedingly complex one, by reason of the topography and configuration of the district/' added Mr. Watkins. "An appropriate solution of the problem is rendered the more difficult by the necessity of utilising, as far as- practicable, the many existing drainage systems, which, from an economical point of view, could not be abandoned. Provision will be made in the scheme for the reception and disposal of sewage, trades wastes and storm water. The alternative sewerage projects will be designed so as to permit of their gradual development to ultimately provide for an area of 125 square miles, with a population of 675,000. It is estimated that this density of population in the area will be reached, under normal conditions, in the year 1970.

"The most important matter to be considered and determined in designing the scheme is the question of sewage disposal. All sewage effluents are ultimately disposed of by dilution, and, in the case of the Auckland district, there must be convenient access to tidal waters. Having in view the selection of suitable sites for outfalls, I have made extensive inspections of the shores of the Waitemata and Manukau Harbours, and the Tamaki River, and also at a number of points along the coast of the Hauraki Gulf, and the coast of the Tasman Sea immediately north of the Manukau Heads. In certain cases the locations which I have selected for the sewer outfalls will permit of disposal without treatment, but in others it would be necessary to install treatment works. lam already prepared to indicate to the board, without prejudice to my final conclusions, the principal features of the alternative sewage projects which I propose to recommend for consideration. Delay in Furnishing Report.

"If it appears that the presentation of my comprehensive report has been unduly delayed, I must refer to the fact that the time at my disposal for considering and determining the many phases of the subject was limited by the necessity of attending to ordinary duties," concluded Mr. Watkins. "Since being relieved of those duties, I have made substantial progress with my report." The chairman, Mr. A. J. Entrican, considered that the engineer should have extra time in which to furnish his report, and further that it should first be considered in committee before being made public. All the members of the board would realise the extent and value of the report which was being obtained at considerable cost. He considered that local bodies not included in the board's area, but who would benefit by the comprehensive scheme proposed, should bear a proportion of the costs entailed. At his suggestion it was decided to receive the interim report, and to allow the engineer a further three months in which to complete his scheme. It was also resolved that the final report should be referred to the whole board in committee before being taken in open meeting.