A chunk of Ashburton’s drinking water history was dismantled recently when 132 metres of steel pipe and eight supporting concrete piers were removed from the north branch of the Ashburton River, near Melrose Road.

From 1964 to the early 2000s, water for the town was primarily sourced from a gallery adjacent to the south branch of the Ashburton River at Greenstreet. Big concrete pipes brought the water about 10km by gravity from the intake and then across the north branch to Farm Road via concrete-lined steel pipes.

Group Manager Infrastructure and Open Spaces Neil McCann said the pipeline was decommissioned 20 years ago, but remained in place until last month when the steel span was removed by Greg Donaldson Contracting.

“All up, 11 12m pipes were taken down and eight concrete piers that held the pipe up over the river were removed. The piers had been collecting a build-up of debris during storm events and one of them was damaged in the 2021 floods. Removing them, and part of the old pipeline, means the river is clear of obstructions.

“Trees had grown up around some of the piers on the banks, showing just how long they had been there. This was a piece of infrastructure that was designed and built to last and it did its job well as the Greenstreet intake was the main source for the town.”

The Greenstreet supply used natural gravity to generate pressure for the town supply; it was supplemented by several bores.

Mr McCann said Council’s Assets team constantly checks and reviews the condition of the drinking water network to identify ageing pipes and programme replacements.

“Managing a large supply involves regular maintenance as well as expansion, and our team is responsible for making sure drinking water is always safe and reliable. There’s a lot of work planned in the next 10 years to meet new compliance standards and that means installing equipment that can monitor and test water quality and quantity in real time.”

Decommissioned pipes are sometimes left in the ground for other utilities to use, for things like electrical ducting, or removed and disposed of. Council worked with Environment Canterbury to schedule the removal work in the river bed.

BELOW: Old concrete piers that once held the steel pipes are being removed from the river too.