Māngere Wastewater Treatment Plant: odour update

12 April 2019

Update, 12 April: Our digesters are now operating normally, but we still need to remove the excess sludge that was stored at the plant while the digesters recovered. During the next five working days, the sludge will be trucked off site. There’s a wind change forecast for Tuesday which means that some odour may carry to Māngere Bridge. We have odour cannons operating, including extra cannons brought up from Tauranga, to help reduce any smells. We also have odour scouts from the air quality department who are taking odour measurements in the community twice a day for the next week. If you notice any significant odours, please phone us on 09 442 2222, option 1.

Update, 5 April: Our digesters are continuing to return to normal operations. However, there’s a wind change forecast for Sunday, from a southerly/south-easterly wind to a south-westerly wind, which means that some odour might carry to the Māngere Bridge community early next week. We apologise for the inconvenience.

Update, 27 March: The chemistry in our digesters is now back in the normal range and the odour has been greatly reduced. We're monitoring the digesters as we begin to return to regular operations. We are working to identify what caused the issue. 

20 March

Part of the wastewater treatment process at our Māngere Wastewater Treatment Plant involves a natural process which uses bacteria to break down solid waste in digesters. The digesters contain a balance of different types of bacteria, but the balance became upset in early February, which has caused increased odour.

We are still investigating what caused the upset and we’re working to get the bacteria levels back to normal. Our eight digesters were affected to varying degrees by the imbalance. Four of them have almost recovered and the other four have been stabilised. We expect they will be back to normal in three to four weeks, with odours reducing before then.

As part of our resource consents, we are required to manage our operations so that there is no offensive odours beyond the plant’s boundary. Therefore, we have alerted Auckland Council to our current situation and we are taking measures to minimise the odours.

We have also let the Māngere Bridge community know what’s happening through social media, by attending the Rate Payers meeting and by responding to phone and email enquiries. Our Māngere Wastewater Treatment Plant Community Liaison Meeting is being held on Friday, 22 March and we will brief attendees.