Treatment plant odour result of tests to remove more ammonia

24 August 2005

Staff at Christchurch City Council’s wastewater treatment plant say the unpleasant smell being produced in recent days is the result of system changes made to see if more ammonia can be removed.

A decision has been taken to cease the trial, however, because its airborne side-effect was “a bit too much to take,” says Mike Bourke, the Council’s water and waste operations and maintenance manager. The unexpected nasal assault should soon be in retreat, he says.

CCC recently said the east city plant was unable to achieve the ammonia output levels set in new resource consents.

The Council, which is in the process of developing a new ocean outfall for the city’s treated wastewater, will seek a change in consent conditions regarding ammonia levels. The new outfall is expected to be operating in 2009 and ammonia levels then should not be a difficulty because of the ocean’s much greater ability to dilute it.

In the meantime, a lot of work is being done to see what changes can be made to get the treated outflow closer to code.

“This latest trial is one of many we’ve been doing to see what more can be done to cut ammonia levels,” Mr Bourke says. “Treatment at the plant is a multi-stage process and with a lot of these things you can’t completely predict what effect, or side-effects, making a change to one part of the system will have.

“Really, you have to give them a go and see, but we always consider the effect our operation may have on our neighbours and that’s why we’ve cut short this particular experiment.”

• Look here for more information about wastewater and the Council treatment plant

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