Major sewerage line threatened by slip on Hutt River cliff

By RNZ

A major sewerage pipe appears to be at risk from a slip eroding a cliff along the Hutt River Te Awa Kairangi.

The slip is also just metres from the edge of busy State Highway 2, below the road and between it and the river.

Thousands of cars pass the spot each day.

It is much closer again to the sewerage pipe, which runs under a walking-biking path at the top of the 6-7m high cliff.

Any rupture might send sewage into the popular swimming spot at Taita Rock.

“Slip remediation will be complex and costly,” said the Greater Wellington regional council.

Wellington Water (WW) says engineers assessed the slip in 2022 but it has not old RNZ what they found.

“We have been aware of this erosion near Taita Rock since 2010 and its potential impact on the wastewater pipe,” WW said in a statement on Friday.

The council’s take was a bit different: “The slip near Taita Rock was caused by erosion at the base of the riverbank in 2014,” it said.

The erosion began encroaching on the path in 2016.

Neither agency made any mention of doing any work to try to slow down or stop the slip.

The Hutt River. Photo / Greater Wellington Regional Council

“We’ll continue to work with other infrastructure providers in closely monitoring the situation,” WW said.

Fixing it might require an agreement and funding between it, the water agency and NZTA, the council said.

It most recently discussed the slip with the transport agency in December, and with Wellington Water in May last year and January this year.

WW is responsible for wastewater pipes between the path and State Highway 2, it told RNZ.

It strengthened barrier fencing around the slip edge late last year and put up warning signs.

It would soon “rearrange concrete blocks previously placed at the slip edge”.

“Greater Wellington actively monitors this slip and will inform WW and NZTA of any changes.”

- RNZ