Problems with the pipe's condition were first raised to Wellington Water by workers on the Riverlink project, seen here in an artist's impression. Photo: Supplied/ RiverLink partners
A pipe that carries all of Upper Hutt's sewage could be at risk in two places, with authorities now trying to work out how to fix a section under State Highway 2 in Hutt Valley.
Last month RNZ reported a sewerage pipe appears to be at risk from a slip eroding a cliff along the Hutt River Te Awa Kairangi.
New Hutt City Council documents show a different part of the same pipe which also carries sewage from Lower Hutt's Western Hills has authorities concerned.
The 360-metre segment of pipe laid in 1963 runs along and under State Highway 2 on the northbound side. It crosses under the highway 150m north of the Tirohanga/Block Road intersection.
Wellington Water has told RNZ it was first notified of an issue with the pipe's condition at the end of March by RiverLink project workers.
The water provider confirmed the pipe was in a very poor condition after a CCTV inspection.
"It was determined through the condition inspection investigation that the section of the pipeline under State Highway 2 is nearing the end of its operational life, due to corrosion."
The pipe also carries most of the sewage from Lower Hutt's Western Hills.
Hutt City Council's Audit and Risk Subcommittee agenda said while the risk of "imminent failure" had not been determined, Wellington Water was taking immediate action to put together a contingency plan.
The documents said councillors would have to consider how they will managed this project and how it related to their draft long-term plan.
New Zealand Transport Agency / Waka Kotahi had been advised of the situation and asked to be kept informed.
RNZ asked Wellington Water if it would have to dig up part of State Highway 2 to fix the pipe. The water provider said it was working through a range of repair and replacement options.
"The options include trenchless techniques which minimise the above ground working area."
Wellington Water said it could not comment on the specifics of the options at this stage.
Lower Hutt Mayor Campbell Barry told RNZ it was a critical asset in the Hutt Valley.
"That's why work has been done to understand in depth the condition of the pipe, and to take these steps now to work out what's the best way to ensure we don't have a situation where there is a failure."
Barry said one of the complexities of the pipe was its location along State Highway 2.
"That will be a significant factor in regard to any potential disruption and costs."
He said it was positive that Wellington Water had notified them the pipe was at risk, rather than when it failed.
"Yes, it might be a bit of an eye roll when people hear it and go 'ah, another problem', but this is actually what we want to see, we want to be proactive in our replacements."
