No end in sight to issues with Hutt wastewater treatment plant
Tuesday, 17 September 2024
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Emitting a foul odour and regularly discharging into the Waiwhetū Stream, the Seaview Treatment Wastewater Treatment Plant is reaching the end of its life and questions are being asked about its future.
Over the next decade, Wellington Water has work totalling $205 million planned to upgrade the plant and address the odour. It does, not, however, have any work planned to stop the increasingly common discharges into the stream.
The Post recently highlighted the issue of treated and partially treated effluent being pumped into the nearby Waiwhetū Stream whenever there is heavy rain or a mechanical issue at the plant, which opened in 2001.
Greater Wellington chair Daran Ponter has said prosecuting the councils and Wellington Water was a costly option for ratepayers. A better solution was for the two city councils to either fund the work required to stop the discharges or build a new plant.
Since August 26, Wellington Water has reported 10 problems ranging from discharges of treated or partly treated effluent into the stream, odour and mechanical breakdowns.
On Sunday, Wellington Water said there had been an “instrument failure” at the plant leading to discharges. The following day it posted that high rainfall within the catchment, leading to higher inflows than the plant is designed for, had resulted in a discharge into the stream.
On May 10, the Greater Wellington Regional Council provided a “please explain” letter regarding “ongoing effluent non-compliance” and the high faecal coliform levels in the plant.
Last week freshwater ecologist Mike Joy told The Post that the Waiwhetū Stream was a “disgrace” and the regulatory authorities should be doing more to force the Lower and Upper Hutt councils to fix the ongoing problems.
A report to a meeting of the Hutt Valley Services Committee spelled out the ongoing problems with the plant.
“The plant remains non-compliant for effluent quality due to high levels of faecal coliforms.”
Petrochemical contamination is also affecting the plant’s performance.
Faecal coliform levels were described as “unstable” and would continue to be so until work to upgrade UV filters is finished.
A list of “discharge events” from April 1 to August 31 appears to be incomplete but notes there were eight discharges into the stream, the worst of which lasted 309 hours.
Discharges of undisinfected but treated wastewater occurred on April 7 and August 26 due to a lack of electrical back for the UV system.
One option to stop discharges into the stream is to build a bigger replacement main outfall pipe. The cost of a new pipe has been assessed at over $1 billion.
Odour from the plant also continues to be an issue, although work is underway to remedy the pong.
The treatment plant has two discharge consents to temporarily discharge into the stream. Both consents are long expired. Since 2018, Wellington Water has relied on a section of the Resource Management Act to discharge into the stream, which was a major source of kai for local Māori.
Greater Wellington had warned Wellington Water that reliance on the RMA was not desirable in the long term.
A 2017 proposal to build a huge storage tank to allow discharges for a further five years lapsed over concerns how it would meet future population growth.
Taranaki Whānui chief executive Kara Puketapu-Dentice said the continuing discharges were a “serious” problem and he wanted to see a solution as soon as possible.
The discharges were having a major impact on the quality of the stream, Te Awa Kairangi/Hutt River and the harbour.
He supported Joy’s call for Greater Wellington to be more proactive and to force Wellington Water and the two city councils to find a solution.
“We will continue to call on councils and Wellington Water to give effect to their responsibilities around the management of our infrastructure … and to stop treating the awa [river] as a dumping ground for the city’s waste.”
Friends of the Waiwhetū Stream deputy chair Rachel Tallon supported the call to quickly find a long term solution.
“The level of eColi and other contaminants in the downstream reaches of the Waiwhetū Stream is of concern to many Hutt residents, local iwi and … to the Friends of Waiwhetū Stream among others.”
On-going monitoring shows the stream’s health is in the “poor to fair range” and is not improving as fast as the group would like.
“The Friends of Waiwhetu Stream would like to see Greater Wellington, Wellington Water, Upper Hutt and Hutt City work together on resolving these issues.”
Hutt City Mayor Campbell Barry said the Hutt and Upper Hutt councils were “actively working” with iwi, Wellington Water, and Greater Wellington Regional Council to find a long-term alternative to using the stream as an overflow.
“While this work is expected to take up to two years, both councils are committed to investing in improvements through the next Long Term Plan.”
He said the Hutt councils had invested $13m into fixing the odour issue over the next three years.