Despite last month’s floods, the building of the new Pyramid Bridge is going well, Gore District Council roading manager Peter Standring says.
Last July, the contract to build the bridge was awarded to Concrete Structures (NZ) Ltd and the building of the $3.79 million bridge across the Mataura River, near Riversdale, started in December.
It was expected the bridge would take six months to build.
Mr Standring said although there was no work on the site for the week of the floods, work resumed quickly after that.
“To date, the work has been tracking along nicely.”
He said the contractor had plenty of warning about the flooding and was able to move most of the heavy equipment to safe ground.
Although a trench box weighing about 2000kg was found downstream on a beach after a helicopter search.
Features of the new bridge included fewer piers, which meant less interruption to the flow of the river and any floating debris, and a new alignment on the eastern approach. The partly constructed bridge held up well in the floods.
“One section from the west bank was in place when the floods hit.
” Even at the river’s peak, there was freeboard (room) under the bridge.
“It showed the bridge was high enough for a significant flood.
” Even if the water topped the piers, the bridge is being built to withstand the side-load of flood waters.
One problem the council and Environment Southland staff were working to solve was a bund (gravel bar) formed by the floods downstream of the construction site, which had caused the river to back up.
“We are at the point of wanting to start work on earthworks for the approaches to the bridge, but the river is too deep, courtesy of the bund.”
No opening day for the bridge had been set.
“The week off-site will have a knock-on effect.”