Drainage Engineer Urges 50-Year Plan

Press, Volume CVI, Issue 31098, 29 June 1966, Page 1

Drainage Engineer Urges 50-Year Plan

A study 7 of requirements for the conveyance, disposal and treatment of liquid wastes in Christchurch up to the year 2020 has been proposed to the Christchurch Drainage Board by its chief engineer (Mr P. J. McWilliam)..

The board’s construction and treatment works committee has deferred a decision until the board’s chief chemist (Mr A. E. Lambden) has been to California to confer with the American designers of the Bromley sewage treatment works about proposed modifications and extensions.

Mr McWilliam has recommended that a Christchurch consulting firm make the study of future requirements, and that they be required to give an interim report within three months and a complete report within a year.

The study will Include development in the board’s district, including foreseeable extensions, the development of the necessary design and loading criteria, and an indication of the possible timing and cost of proposed works. The engineer said in his report that the study was needed because of the increasing load at the Bromley sewage treatment works, and

the likelihood that there would be an upper limit to the loads which could be treated there economically. He said that in the United Kingdom it was considered that a plant to treat the wastes from a population equivalent of about 1,000,000 persons was the upper economic size. But with the more open development of Christchurch it was likely that the most economic population equivalent load to be treated at Bromley would be less than 1,000,000 and might turn out to be similar to the 700,000 population equivalent to which the Bromley works could readily extend. The consultants would be asked to say what this figure was for Bromley, and to what area and including what industrial wastes it corresponded.

If urban domestic and industrial liquid wastes were going to exceed the ultimate capacity of Bromley, they would be asked to say where the excess should be directed for treatment or disposal, how it should be done and when. The study would also include the reassessment of present proposals for treatment and disposal requirements, as well as the preparation of a broad outline plan of future trunk sewer requirements.