The West Coast Regional Council has applied to itself for resource consent for first phase works of a Government-funded $12.3 million project along the Waiho (Waiau) River to protect Franz Josef Glacier township.
The Waiho (Waiau) River and State highway bridge at Franz Josef Glacier. The stopbank to the left is to be raised and extended 2.5km. Photo: LDR / Brendon McMahon
It is seeking consents for 35 years to help protect the township for the next 20 years from a one in 100-year flood event.
It involves 2.5 kilometres of stopbank work.
This includes raising the existing stopbank by 2m from the St James Anglican Church and the town heliport, to the 'Havill Wall' in front of the sewerage ponds. It also involves constructing a new 5m high NZ Transport Agency bank to link the Havill Wall and heliport stopbanks.
A rock lined bund from the end of the Havill Wall will run to the north-east along the riverbed to prevent overflows into the adjacent Tatare River.
"This work is required as the bed levels of the Waiho River have been rising by approximately 180mm per year for the past decades," the application says.
"No negative effects are expected."
Consent is also pending to lift the height of the existing stopbank on the south bank, from the bridge and then downstream as far as Canavans Knob, to protect State highway 6.
Construction will begin next week on the north bank and be finished by February. The successful contractor is MBD of Greymouth.
The application says gravel will be excavated from the riverbed and transported to the stopbank areas either being raised or constructed.
"Rock for armouring of the new stopbanks will be obtained from multiple sources and transported to site by rock trucks."
Because the proposed new stopbank links two existing banks together, the alignment will ensure the active river channel runs parallel with the new and existing work, the council says.
The Government approved $12 million for the south bank work also, but then paused that while it considers the long-term future of the stopbanks in that area, with calls to abandon the protection works altogether and let the river flow freely. That will involve compensating property owners on the Waiho Flat.
It has only approved the first stage of works on the south bank, to Canavans Knob.
Regional council director of operations Randal Beal said today some final design details were being worked through with the NZ Transport Agency and Department of Conservation before a separate consent application could be lodged.
"The south side is a wee bit more complicated."
The stopbank to be raised was not the high bank running alongside the highway, but a longer bank running parallel to that and nearer the main river channel, Beal said.
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