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We recognize that these objections are entitled to the fullest consideration. It would, of course, be most unfortunate if the benefits which following from the natural .advantages of the harbour were to be prejudiced in any way, and before any sewerage scheme involving the use of the harbour is adopted the greatest possible care should undoubtedly be taken to ensure that this will not happen. (5) We have explained in paragraph 34 that the complete purification of sewage can be erected by standard treatment processes and in paragraph 33 the purification that is brought about by dilution in water is shown. We must repeat that these are matters that cannot reasonably be doubted. We must also repeat that there exists •a great deal of misconception on this subject which it is essential should be removed. It is plain that much of the criticism that has been made against the Brown's Island scheme is due to the failure to pay proper regard to the complete protection from pollution that can be effected by the use of modern, well-proved processes. (6) In the circumstances it is surprising that, on the whole, so little attention has been paid by the critics of the Drainage Board's proposal to the possibilities of treatment processes. In several instances the critics have admittedly no knowledge at all of this subject. It is to be observed that, although the Board's proposals have been strongly criticized by the Drainage League, the expert witnesses called on behalf of the league did not suggest that it was impossible or impracticable to render innocuous the sewage proposed to be dealt with at Brown's Island. The league's consulting engineer, Mr. R. P. Worley, criticized the Board's proposals on many grounds. He contended, for example, that the proposals did not make provision for secondary treatment, and that too much reliance was placed on the effect of the primary treatment proposed. He contended, also, that Brown's Island was not large enough to cope with the population that will probably require to be served after the year 1980, assuming the sewage from the whole of the isthmus (Scheme No. 1) is dealt with there. Further, he criticized the proposals on the basis of the comparative costs of the Board's and league's proposals respectively and on various other grounds. The principal criticism made by him was, however, the unsuitability of Brown's Island for the operation of a full-scale composting scheme as advocated by the league. Mr. Worley frankly admitted that, disregarding the league's utilization scheme, the Board's proposals constitute " a very good engineering proposition," and he did not suggest in any way that, provided adequate treatment of the sewage was given, there was likely to be any danger to public health. When questioned about the standards of purity which have been prescribed by the Harbour Board and the Health Department for the waters near Brown's Island, Mr. Worley very fairly and properly said : I would sooner see a higher degree of purification for all sewage discharged at Brown's Island than has been fixed, but as a citizen of New Zealand I would be quite prepared to abide by the Health Department's dictum in the matter. I could not take any other attitude towards it. (7) Mr. T. McKnight, who gave evidence on behalf of the Yacht and Motor Boat Association, admitted that he had no knowledge of sewerage engineering, but notwithstanding this handicap he advocated not only that the purification of the sewage should be " the greatest purification that is humanly possible," but also that the outfall should not be in the Waitemata Harbour at all and should be at a point in the Manukau Harbour almost at the Heads. The witness also stated that, however strong were the assurances of experts that there would be no danger of the pollution of the Waitemata Harbour, he would not be satisfied, but he subsequently modified this statement and said that if his association had an assurance from " The President of the B.M.A. or something of the sort that the stuff is not harmful and would remain harmless we could not object. The yachtsmen will certainly accept it." (8) Similarly, Mr. W. 0. Stocklev, the chairman of the Auckland Centre of the New Zealand Swimming Association, stated that the centre objected " to any form of sewage discharge into the Waitemata Harbour," and in the course of his evidence he

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