ORAKEI SEWAGE.

Auckland Star, Volume LXIII, Issue 303, 22 December 1932, Page 19

ORAKEI SEWAGE.

CHLORINATION PROPOSAL.

further report required.

The suggested installation of a chlorination plant at the main outfall works, Orakei, was the subject of a report submitted to the Auckland and Suburban Drainage Board la-st evening by the secretary-engineer, Mr. H. H. Watkins.

Mr. Watkins said that in the course of his official tour abroad he found that the chlorination of sewage was extensively practised in other countries, more particularly in the United States. It was applied to the sewage, either from solution tanks or by flow-regulating devices. Sewage chlorination plants were installed for disinfection of effluents, to protect water supplies, bathing beaches and shell fish growing areas, and also for odour and fly control and the prevention of filter clogging. Chlorine Was usually applied to settled or clarified sewage, and it must be understood, therefore, that the beneficial results likely to be attained by the installation of a chlorination plant at Orakei, would he limitpd to some extent, by reason of the fact that the sewage was untreated •other than by screening. A suitable plant could be installed at the works, at an &rtimated cost of £650, comprising a 'standard" automatic chloronome, with control apparatus and a set of chlorine containers.

Mr. Watkins said the annual cost of operating the plant would depend upon the chlorine demand of the sewage, and ;the actual periods of chlorine application, which could be accurately ascertained only by means of experiments. The general practice was to limit the application of the chlorine to the dry-weather flow periods. Allowing for a total application period of five months each year, he estimated that the operating cost would ,not exceed an expenditure of £800 per annum.

In reply to a question by Mr. Lawrence Taylor, Mr. Watkins said that it would «be three years before any new comprehensive scheme to cover the drainage for the whole metropolitan area could be put into operation, and he thought that the installation of a chlorination plant, Sunder the circumstances, would be good work, if the money could be found. The Mayor, Mr. G. W. Hutchison, ; thought the suggestion excellent, and ofte the public would appreciate. It was decided to instruct the engineer to supply a full report upon the chlorination of the Orakei works as early a.s •possible.