$1b to stop overflows into Waiwhetu Stream

Wednesday, 19 June 2024

Paul Bellamy and daughters Miyo Bellamy, 8, and Assay Bellamy, 6, pick up rubbish along the Waiwhetu Stream. The stream is used as an overflow from the nearby Seaview Wastewater Treatment Plant. (File photo)

A solution could cost up to $1 billion and take decades but calls are growing for Wellington Water to stop using the Waiwhetu Stream as an outlet for treated effluent from the nearby Seaview Wastewater Treatment Plant.

The discharges are caused by old concrete joints on the outflow pipe starting to fail. The pipe takes effluent from the treatment plant to the Pencarrow coast, where it is discharged into Cook Strait.

Discharges make it unsafe to swim, fish or collect shellfish in the lower reaches of the stream and Hutt River, as well as parts of Wellington Harbour.

Both the Friends of Waiwhetu Stream and Taranaki Whānui say that after years of discharges, it is time to find a final solution.

Te Rira Puketapu, known as Teri, battled for years to get the stream cleaned up.

The call for action comes after residents in Porirua forced a last minute change to their council’s long term plan. The Porirua wastewater treatment plant also struggles in heavy rain, discharging untreated sewage in to a nearby stream and the ocean.

Taranaki Whānui chief executive Kara Puketapu-Dentice recently talked at a conference on stormwater, organised by Water New Zealand, calling for action.

“All I have to say is get on with it – fix the problem - and sort your shit out.”

The Hutt City Council’s consent for the overflow discharges goes back to 2011, when it applied for a new 35-year consent.

It was opposed by local Māori and Friends of Waiwhetu Stream, which at the time accepted that overflows were necessary but argued that 35 years was too long.

The council accepted the feedback and proposed a five-year extension, to the existing temporary discharge consents, while they undertook a series of further investigations.

When the resource consents expired in 2018, the council lodged an application for new temporary discharge consents, based on relocating the discharge point into the Te Awa Kairangi/Hutt River estuary, adjacent to the mouth of the Waiwhetu Stream.

Residents from Tītahi Bay protest before a Porirua City Council meeting about raw sewage overflow from Rukutane Point Pump Station. The council subsequently agreed to fix the problem.

The temporary extension, however, was overtaken by Greater Wellington’s Natural Resources Plan, which provided a number of protections for rivers and estuaries.

Wellington Water posts regular warnings about the Waiwhetu Stream.

The river mouth and estuary is classified as a “site with significant mana whenua values” as well as an important area for native birds.

Grant Webby, a member of Friends of Waiwhetu Stream, has followed the issue since the organisation was formed and says it is clear that the council would struggle to get a new consent to discharge into the stream or the river.

Although he understands it is a complex and expensive issue, he is looking for some urgency in the process to find a solution.

“They need to demonstrate they are actually doing something. It has been a case of the slow boat to China.”

Puketapu-Dentice also wants to see some progress.

His late uncle Teri Puketapu fought for decades to have the stream cleaned up and to stop discharges.

The ageing treatment plant also has issues with odour and Puketapu-Dentice says it is offensive to Māori, especially as the stream runs past an important urupa.

The Seaview Wastewater Treatment Plant needs a major upgrade to deal with odour issues. The outfall pipe is also a cause for concern.

“My awa is not your drain – it is a source of sustenance, pride and mana … it caresses the banks of the land in which my people are buried.”

Council three waters adviser Bruce Hodgins says that a solution would be neither straight-forward nor cheap.

“The amount of money for this is astronomical, we are talking somewhere between half a billion and $1 billion.”

A group including councils and iwi is looking at the issue and he accepts that discharging to Te Awa Kairangi is not a feasible alternative.

In a written statement Wellington Water confirmed the consent to discharge treated wastewater expired in February 2018.

Discharges continue to be authorised under the previous consent, until a decision is made on the new consent applications.

There were 24 discharges in the past 18 months.

The most recent assessment of the environmental impact found “the discharges may have increased the level of risk in respect of both contact recreation activities and aquatic ecology of the Hutt Estuary, although this increased level of risk is expected to be temporary in nature, and is unlikely to have any long-term impacts'.

Wellington Water estimates that replacing the main outfall pipeline with a new pipeline and larger capacity to remove the intermittent discharges would cost approximately $700 million.

The 18km outfall pipe, which serves 150,000 residents in the Hutt Valley, was commissioned in 1962.