FAQs

Why are you doing this work?

This pipe transports wastewater from Aotea, Whitby, Mana, Papakowhai, Plimmerton and Cambourne so it’s an important part of the Porirua water network.

Despite repairs in July, this pipe remains in a fragile condition. We anticipate it could fail again in heavy rain. For this reason, we are fast-tracking this work.

It’s important that our communities have a safe, reliable and long-lasting water network.

When will this work begin and how long will it take?

Work will begin in late September and is expected to be completed by early 2022.

How old is this wastewater pipe?

The pipe was laid in three stages between 1975 and 1978.

Why did the pipe deteriorate?

The wastewater pipe in Paremata was designed as a pressure pipe but the section which burst in July alternates between full flow and part flow due to the terrain. This has caused the condition of the pipe to deteriorate faster than expected.

How many kms is the pipe and how much of it will need to be replaced?

In late September we will begin work to replace a 1km section of the pipe that is likely to fail again.

The pipeline, running from Paremata to the city centre pump station, is around 4.5km in length. This pipe transports wastewater from Aotea, Whitby, Mana, Papakowhai, Plimmerton and Cambourne so it’s an important part of the Porirua water network.

This work is the first phase of a staged approach to upgrade the main from Paremata to Porirua (4.5km), which is essential for future growth.

How much wastewater does this pipe transport and what is it made of?

During dry weather, around 5 million litres of wastewater flow through it daily.

This pipe transports wastewater from Aotea, Whitby, Mana, Papakowhai, Plimmerton and Cambourne so it’s an important part of the Porirua water network.

Is this one of the pipes that is overdue for renewal?

This wastewater pipe under SH1 was planned for upgrade in 2025. Renewal of pipes is usually based on pipe condition. The condition wasn’t known until recently.

Are other pipes of the same age/type likely to be in this condition?

We currently have an inspection programme on our very high criticality assets that includes our large pressure pipelines like this one. Physical inspections of these pipes are particularly difficult due to the limited time that they can be taken off-line. So, we are working with experts to utilise the best available tools for such inspections.  At this stage our assessments have not found any other pipes in a similarly poor condition, but this may change as the current work programme advances.

Will this disrupt traffic?

Most of the replacement work is expected to be done without lane closures. However, some work may require a temporary lane closure at off-peak times. As always, we will work to reduce the impact on residents and the public as much as possible. We’d like to thank the public in advance for their patience as we carry out this important work.