The stink that will not go away

Tuesday, 27 August 2024

Wellington Water network general manager Jeremy McKibbin inspects the bark used to deal with odour at the Seaview Wastewater Treatment Plan.

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It could get a bit more stinky in Seaview.

The Seaview Wastewater Treatment Plant has a long history of odour issues and, over the next decade, Wellington Water has work planned totalling $205m to upgrade the plant and address the smell.

Last November, businesses in Seaview described it as a suburb that smelled ”like a three-day-old portaloo“.

Work has now begun to deal with the odour issue, which has been an on-going source of annoyance to neighbours. It is being staged and should be completed by 2026.

Wellington Water recently posted on social media that locals could expect to notice an increase in odour, whilst the work was underway.

For decades the Hutt City Council has discharged treated effluent into the Waiwhetū Stream. Local Māori and Friends of the Waiwhetū Stream say that has to stop.

“We’re doing our best to minimise the risk and will be operating the odour neutraliser. We’ll also be keeping an eye on odour levels on site and outside the plant boundary.”

The $13m project includes upgrades to biofilters and the sludge drying facility.

Network development and delivery general manager Susannah Cullen said the objective was to reduce odour levels and their impact on the community.”

The Seaview Wastewater Treatment Plant is having $205m spent on it over the next decade.

The biofilter treats odour in the plant by passing the air through a bed of bark, gravel and limestone chips containing microbes that break down the compounds that cause the smell. .

The upgrade involved installing a new air distribution system beneath the bark and other material, and the installation of a new cell isolation system.

Wellington Water is planning to work on one biofilter at a time (there are six).

That meant there would be five cells in operation to treat odour, Cullen said.

Given that the treatment capacity would be temporarily reduced, an increase in odour levels was possible.

“We are taking steps to minimise the potential odour from this work. This includes use of an odour neutraliser spray and staging works in a way that maintains an acceptable level of treatment capacity.“

The Seaview Treatment Plant is the source of a smell that can be smelt as far away as Naenae.

Cullen said Wellington Water and the Hutt councils were committed to reducing odour levels.

“It will take time as we work through the areas of the plant that have been identified as the main sources of odour.”

Over the next decade, Wellington Water is planning significant work to upgrade the plant, including $90m for a new sludge dryer.

The council’s three waters advisor, Bruce Hodgins, said the work planned showed the two councils which funded it (Hutt City and Upper Hutt) were committed to upgrading the plant.

It was dnot a case of addressing historical under investment. The plant has a lot of moving pieces that were coming to the end of their life and over the next decade would be replaced.

The reality, however, was that it was impossible to get rid of the odour.

“It should lead to a significant improvement but the nature of the beast is that it is never going to reduce every smell.”

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