Wildlife flee pungent Christchurch wastewater plant

The birds have winged it, humans want to leave and even the midges appear to have flown away from the foul-smelling wastewater plant in east Christchurch.

The plant's oxidation ponds double as a wildlife reserve but are now one of the worst causes of the horrendous stench that is driving everyone - and everything - away.

On Dyers Rd, pukeko crossing signs continue to alert drivers to the scores of birds that usually hang around the ponds. 

But since the fire last year, resident Damian Elley has noticed a big change in the water.

The wastewater treatment plant in Christchurch Photo: RNZ / Niva Chittock
The wastewater treatment plant in Christchurch Photo: RNZ / Niva Chittock

"The water's appearance is definitely stale. The edge of the concrete that's a couple of metres into the water is harder to distinguish, giving a real solid effect. And it's usually particles that you notice - some sort of build up - I'm not a 100 per cent sure what it is," he said.

He claimed it was impacting the surrounding environment.

"We're not seeing midges, which used to be a huge problem. We're not seeing birds. We're not seeing eels - we're not seeing anything alive any more.

"The reason the wildlife's gone is because the water's dead, there's no oxygen in the water and nothing can live in it," Elley explained.

The stench is strong at the side of the water because the raw waste is not being treated to the same quality as before the fire destroyed the trickling filters.

"The council says look at the trickling filters, we've lost the roof on each of them, we can't use them any more. But ... the waste is now going straight into the ponds - which are also called Bromley Wildlife Reserve," Elley explained.

"But the animals can't live here. The people of the Bromley community just about can't live here but unfortunately, we can't just pack up and go like the birds can."

Damian Elley. Photo: RNZ / Niva Chittock
Damian Elley. Photo: RNZ / Niva Chittock
Elley believed the solution would be neutralising the water chemically and has raised this with Christchurch City Council.

But he said it was not doing it because the treatment costs thousands of dollars.

Council has carried out water testing but has not yet shared the results with RNZ.

It said financial and wellbeing compensation would be offered to residents in the immediate vicinity but the details were yet to be determined.

Jo, who lives in Burwood, doubts that would be enough.

"In my mind, I'm thinking immediate vicinity is a couple of streets that are very, very close - next to the plant," she said.

"I would say at least, at the very minimum, the entirety of Bromley need that assistance, not just the immediate vicinity of the plant."

The stench got bad at Jo's place six weeks ago, when she woke up in the middle of the night thinking her cat had defecated in her room.

The wastewater treatment plant. Photo: RNZ / Niva Chittock
The wastewater treatment plant. Photo: RNZ / Niva Chittock
Since then she has been sleeping with a eucalyptus tissue over her face to get a little reprieve, and said her son's asthma was worse.

Jo hoped the city council will decide to use a criteria system not just street names or postcodes to decide who should be eligible for compensation.

"It's horrendous. My youngest, he has asthma, so it really concerns me what damage the smell could be doing to him if it's giving me a sore throat.

"I'm considering going to the doctor's if his asthma continues to be bad - it's just so unusual for it to be like this, it's normally mild."

Today, the city council cancelled its free well-being workshops for the community, due to lack of interest.

It said it was open to holding them again in the future at the community's request.

Specific compensation options like reimbursement for air purifiers, free healthcare appointments and paid trips to hot pools, will be put to councillors in a meeting next Thursday.

Very low bird-life on the oxidation ponds - ecologist
City council ecologist Andrew Crossland said long-term monitoring is in place for wetland bird numbers in the oxidation ponds and wider estuary areas.

He said it confirmed numbers on the ponds are indeed very low at the moment.

"This is a response by those birds that normally feed on the ponds to the changes in operation of the treatment plant that were necessary following the fire in November. These changes have led to a temporary deterioration in the water quality of the oxidation ponds.

"The loss of the trickling filters means that the ponds are receiving much higher loadings of organic matter. This has resulted in a dramatic reduction in midge numbers, a major food source.

"The combination of the changes in water quality and loss of food source are thought to have resulted in a dramatic displacement of some wetland bird species (particularly NZ scaup, NZ shoveler, black-billed gulls, black-fronted terns and welcome swallows) to other sites across the region.

"Other species able to find alternative food within the wider estuary area (such as grey teal and black swan) and have relocated locally to areas such as the Lower Avon and Heathcote River saltmarshes, Bexley Wetland, the eelgrass beds on the eastern side of the estuary and the Gracilaria weed beds in Heathcote Bay."

Crossland said birds that don’t feed in the oxidation ponds, but rather rest on the water like Canada geese or up in the trees like cormorants and royal spoonbills have not been impacted.

Species like godwits, oystercatchers, herons and pukeko that feed only on the estuary or paddocks are still at normal population levels for this time of year.

"The recovery plan for the plant is being implemented and we expect to see steady improvement in the quality of the wastewater being discharged to the ponds over the next few months," Crossland said.

"As the water quality improves and the midges return, the habitat for the birds will become much more attractive.

"Our ecology and park ranger staff will continue to monitor bird numbers and work with the Three Waters team to get the native water bird carrying capacity of the oxidation ponds back to normal as soon as possible.

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