Work to restore Christchurch's earthquake-damaged New Brighton pier is nearing completion.
To enable repairs, waterproof tube casings called caissons were built around the pier's pylons by Fulton Hogan.
That allows workers to operate at sea level, strengthening the columns underneath, while being protected from the water.
Fulton Hogan is building four-metre-wide casings around the columns, then burying them metres deep in the sand, by using water jets to blast the sand on the sea floor away and lowering the casings, as the sand resettles.
The $10 million project began in February and is on track for completion by April next year.
Project manager Hayden Sturzaker told Stuff it took some time to figure out how to do it.
"The biggest challenge with that is, of course, access," he said. "To obtain access, we're required to install casings around each individual column.
"They're assembled from the pier deck. Once they hit the sea bed, we fluidise the sand with high-pressure jets.
"Imagine standing in the sand and sort of moving your feet and you settle - we're just doing that with water under pressure. That's what creates that turbulence and allows the casings to settle."
Newshub.
