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EUROFLO® Part of $14M SH1 Project

EUROFLO® at Mangamuka Gorge

EUROFLO® Part of $14M SH1 Project

After a massive storm caused flooding and damage in Northland, EUROFLO® pipe was chosen as part of the rebuild solution.

The storm in July 2020 was classed as a ‘one-in-500-year’ rain event — with 250mm rainfall recorded in some places in less than 24 hours — and caused a number of major slips in the Mangamuka Gorge on SH1.

Mangamuka Gorge SH1 is a key route linking Kaitaia to the rest of Northland but the extensive damage to a 13km section of roading saw the route closed for 11 months and required a massive, collaborative $14 million-project to restore.

Engineering consultancy WSP worked on the project alongside Waka Kotahi, Fulton Hogan and a number of subcontractors.

To resolve the worst of these slips, which caused the evacuation of land above and below the road, WSP needed to redirect the watercourse that came out of the hillside and run it under the road.

“We needed to discharge the water further down the bank but because of the slope and the roading we needed a flexible pipe that we could run on a curve,” says Shaun Grieve, a civil engineer with WSP.

EUROFLO® pipe offered the flexibility they needed and the large diameter required to cope with the water flow.

Products used in the project included 15 lengths of SN8-rated 800mm (OD) pipe with rubber rings, a joiner and bend.

Given the challenging nature of the physical environment the project team was working in – steep slopes, natural landscapes that needed to be preserved, and the need to manage Kauri dieback risks – the right pipe also had to meet other key criteria.

EUROFLO® pipe was light enough for the contractors to handle and position correctly, despite the steep, sloped site.

“The challenges of the site also meant we were looking for a solution that could essentially be maintenance-free, strong enough to last and not likely to back up, which is why we chose to run the culvert down beside the road.”

“It was a challenging project but it is really satisfying to see it come together and know we played our part in fixing the damage and getting those roads reopened.”

WHERE: Mangamuka Gorge, State Highway 1 – Northland
WHEN: July 2020 – June 2021
WHAT: Culvert installation after extreme flooding and slips
EUROFLO®: 5.8m lengths of 800mm SN8 EUROFLO® pipe, plus rubber rings, joiner, bend

Download a copy of the case study here