Red stickered but stoic in Nelson's slip zone

Tuesday, 23 August 2022

Geotechnical adviser Grant Maxwell is part of a team assessing homes under threat from landslips on the Tahunanui Hills.

Euan Mitchell’s Nelson home has been red stickered. The back of the Moana Ave property in the Tāhunanui hills is surrounded by shin-deep silt and mud.

Mitchell has owned the home for about 18 years, before it was struck by a landslide last week.

The tenants have left and gone to a motel. They had only moved up from Christchurch three weeks ago.

“The hill’s come down,” Mitchell said on Tuesday, outside the house he is prohibited from entering.

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“The neighbour’s probably caught most of it on his driveway. I’ve had a bit of a river with rocks and silt just come down the hill. It’s just banked up at the back of the house.”

Mitchell said he was in contact with the Nelson City Council on Tuesday morning, but said it would be “crystal ball gazing” as to when it would be habitable again, though he did have insurance that would cover things like lost rent.

Civil Defence geotechnical response lead Grant Maxwell at Grenville Terrace, Nelson. Residents have been evacuated from the Tāhunanui Hills street as a landslide damaged Days Track and caused cracking and land movement in Grenville Terrace.

Mitchell’s house is one of 15 with red stickers in Nelson after last week’s flooding and landslips. It means they have been assessed as having significant damage or land stability issues and should not be entered under any circumstance.

Another 108 properties have yellow stickers, meaning have been assessed and can be entered temporarily only to secure or remove items.

A red-stickered home in Sunningdale Drive, Stoke, A landslide at the back of the home moved the house including kitchen cabinets.

Residents may or may not be able to stay overnight in yellow stickered homes, depending on the individual assessment. Classifications can change as more assessments are made.

The stickered homes are in clusters across the city, including the Tāhunanui hills, in Stoke and those badly affected by Maitai River flooding.

Like many in Nelson, it feels like Groundhog Day after 2011's floods.

Craning his neck upwards, Mitchell points to the steep hill face that’s now muddied and stripped of vegetation.

“That whole hill up there was bare last time. It took about two years to regrow.”

Mitchell has been stoic about the experience: “I don't want to sound blasé, but when you know it's coming, it's like you prepare yourself. If you watch the news, people are 100 times worse off than I am. I’ve still got my house there at the end of the day.”

Civil Defence geotechnical response lead Grant Maxwell said about 350 homes have been affected by landslides, and of those, about 130 were evacuated.

Maxwell said getting people into homes was a priority at the moment, and the reinspection teams were working really hard to achieve that.

Around 50 properties were evacuated from the area known as the Tāhunanui Slump – from Rocks Rd all the way back up the hill, which Maxwell describes as the “largest singular area where there have been evacuations”.

“Lots of that is quite precautionary because we want to be really careful to not put people at risk,” Maxwell said.

“The Tāhunanui area has a very long history of instability, which predates settlers. It's really old and really deep as well.”

The Grenville Terrace slip was 'a reactivation of an event that we noticed in 2011”, he said.

Across Nelson, teams of about 30 geotechnical people are working in the field, paired up in teams for safety, inspecting and reinspecting risks.

With rain forecast for the end of the week, Maxwell said the risk of further events will “elevate” over Thursday and Friday, but it was difficult to predict.

“We do know that whilst the water is receding slightly and the saturation levels of those landslides, any additional water could have an impact, so we are needing to be very careful.

“As we get to Thursday and Friday we will be reinspecting everything that we can. Now that we know where the hotspots are, we'll be able to deploy really quickly.”

Speaking generally, Nelson had “really good basement geology, so really good strong stuff”.

Most of our “failures” tended to be about a maximum of two metres deep, but when they liquidised and mobilised they did “get up some speed sometimes”.

Group information manager Nelson Tasman region Paul Shattock said as a community we had to be aware that climate change was happening.

“We are seeing impacts of that, and we just have to adjust accordingly and as a community continue to work together.”