More resilient flood protection work is on its way for a Central Otago community.

A one-metre square culvert is about to be replaced by one eight times bigger to improve road flooding resilience in Roxburgh, says Waka Kotahi NZ Transport Agency.

It will measure four metres by two metres and will be installed at Golf Course Creek on State Highway 8 in coming weeks.

Golf Course Creek is the second of three culverts identified for renewal in the area, with Pumphouse Creek culvert already replaced in 2021 and Black Jacks up for renewal next year, 2023.

“The creek had an ongoing risk of flooding,” says Waka Kotahi Senior Network Manager *Robert Choveaux.

“Gravel has been accumulating which resulted in blockages following heavy rain in the hills, which has occurred more frequently in recent years. The larger culvert will help channel flood waters and gravels under the road down to the Clutha River.”

Timeline

There are three stages to the culvert replacement:

• Preparatory work late October to early November involving short delays for road users and a slower speed through the site.
• Culvert installation 6-14 November – full road closure and a detour.
• Finishing work – mid November to December – short delays, slower speed through the site.

Service relocations and site clearance work on the highway shoulder will start this week leading up to a road closure in November. There will be short delays and a reduced speed limit while the preparatory work is underway.

“We understand these works will have a real impact on road users, particularly locals who may have to use the detour regularly,” says Mr Choveaux. “However, initial feedback from the community has been mainly positive with local residents and businesses understanding its importance. We will continue to work with them to limit disruption as much as possible.”

Cost to complete physical works is around $680,000 and follows a series of floods in recent years. Waka Kotahi has been working with the Otago Regional Council which completed a catchment study of the area.

The work programme and the detour/road closure

• Work will run from the last week of October, with minimal impact upon road users initially, into December. It is possible some low impact finishing work will occur in the New Year.
• From 8 am Sunday, 6 November to 8 am Monday, 14 November, there will be a 24/7 traffic closure as the old culvert is removed and the new one is positioned.
• The detour route, on the eastern side of the Clutha River, will take northbound traffic on SH8 onto Millers Flat Bridge Rd across the Clutha River, onto Teviot Road for around 17km, onto Jedburgh St and back onto SH8. (Reverse for southbound traffic – see maps below). As the Millers Flat Bridge is a single lane structure, there will be automatic traffic signals operating to manage traffic flows.
• Local residents on either side of the worksite may need an extra 25 – 30 minutes to navigate via the detour when travelling around their community, however vehicles that were intending to travel straight through Roxburgh via SH8 will have around five minutes added to their total journey.

Pedestrians and cyclists

• There will be no crossing points through the worksite for pedestrians or cyclists during the eight-day full road closure. Residents are asked to keep pets and children away from the site as much as possible over the construction period, given the heavy machinery being used.

Detour route – not suitable for all freight and over-dimension vehicles

• The detour route, on the eastern side of the Clutha River, is not suitable for all freight traffic and over-dimension vehicles.
• While High Productivity Motor Vehicles (HPMV) and 50MAX truck trailers can take the detour route, overweight vehicles and over-dimension loads will not be able to. For all OD load enquiries please contact CODC directly.

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Waka Kotahi thanks all regular users of this route and affected residents for their patience around this road closure and detour. “Special thanks also for drivers slowing around crews in the lead-in to Christmas,” says Mr Choveaux. “We want everyone to get home safe.”

· *Check this short video with Robert Choveaux and Central Otago District Mayor Tim Cadogan explaining the reasons for the culvert replacement. https://youtu.be/Is422r9EldY

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