Remedies at sewage works

Press, 11 April 1977, Page 10

Remedies at sewage works

If smells are the worst that the people of Christchurch need fear from the sewage treatment works at Bromley the city may not be happy, but it will be fortunate. This thought may not reconcile those who live near the works to the particularly obnoxious smells issuing from them at present; and people elsewhere in the city have recently had a whiff of what the works can do. But even the treatment station’s neighbours are probably grateful that the Drainage Board has kept sufficiently on top of the problem of disposing of Christchurch’s sewage to prevent worse forms of pollution issuing from the works.

Had the Drainage Board not embarked a few years ago on an ambitious programme of modifications and extensions to its plant, Christchurch might now, or in the near future, have found itself in the same kind of serious situation as Auckland. The works at Mangere have been unable to deal with the full flood of Auckland’s effluent and the failure there has been to the detriment of the waters of Manukau Harbour. The Christchurch Drainage Board has had in the past, to apply for permission to discharge partly treated effluent into the Avon and Heathcote Estuary, but the Estuary has never been as close to being seriously polluted as has Manukau Harbour.

The smell which is plaguing parts of Christchurch is one of the costs the community is paying for avoiding possibly serious pollution of the Estuary and for averting possibly more offensive smells hanging over the eastern suburbs.

The smell is bad at present because further construction has coincided with dry weather and with the teething problems of bringing the first of the new trickling filters into operation. In the past, the works have smelled because the filters and oxidation ponds have been overloaded even in fairly normal circumstances. This should not recur once the modified and extended treatment plant is working fully.

By the end of the year, when the second new trickling filter and other new equipment have been completed, both bad smells and the possibility of a polluted Estuary should be things of the past. This goal will be achieved later than the Drainage Board once hoped, and the blame for the delay cannot be laid entirely on the board.

Some people in Christchurch are suffering now' because of the delays, but the thought that the smells are bad now largely because of efforts to prevent pollution in the future should help to encourage public patience.