Overhaul for coastal waterway
The $400,000 repair of the Waihao Box has started.
The box was built in 1910 to create an opening through the gravel beach to the sea for the Waihao River and Wainono Lagoon.
However, in recent years, coastal erosion and storm damage have caused major wear. Environment Canterbury (ECan) river engineer Bruce Scarlett said repairs would take up to two months.
Most of the heavy machinery arrived on site yesterday. A pile driver would arrive next week.
"We're banking on the weather as it's a big job, but if we get this right, it should protect the box for another 30 years," he said.
Mr Scarlett said the work would involve taking apart about 20 metres of the box at the seaward end and shifting the entire structure several metres inland in response to changes in the coastal profile.
"We're rebuilding only 10 metres of that 20m; it's a repositioning job. Some of the timber is over 100 years old and falling apart. We need to fix this as it's so important for the effective drainage of the Waihao and Wainono catchments."
Mr Scarlett said the reserve at the end of Byrnes Rd would have to be closed during the work.
"This is already a hazardous area because of the often heavy seas and the shifting nature of the gravels around the box."
The box has been repaired at least four times during its existence, with the last major work in 1977. ECan took over management of the box in 1996.
The repairs could cost more than $400,000, mostly funded by the Wainono Drainage Group - a group of about 30 ratepayers farming on the lagoon margins.
The group's spokesman, Mick Laming, said it had to go into debt to cover the costs. "But it is a necessary project, as the box has become woven into the overall ecology of the river system."
Mr Scarlett said the group's costs would be recovered by rates over an extended period.
- © Fairfax NZ News