The debris that caused the SH1 Ashburton/Hakatere River bridge to close will be cleared “in the next fortnight”, Waka Kotahi says.

Environment Canterbury has jurisdiction over river management, but as the debris is impacting the bridges it will be Waka Kotahi New Zealand Transport Agency and KiwiRail’s job to remove it.

Waka Kotahi is responsible for debris up against, or within 50 metres of, a bridge or culvert, senior network manager for Mid and South Canterbury Scott McKenzie said.

The work is planned to occur in the next fortnight “when flows further reduce to allow easy access and safe crossing to get all of the debris off the piers and clear of the structure in one operation”.

“We will also be completing works around the KiwiRail bridge, taking a collaborative approach previously agreed from prior flood events."

It was suggested at a recent Ashburton District Council activity briefing meeting that Waka Kotahi would use a digger from the bridge to clear some debris as a trial for doing preventative clearing during a flood event, but McKenzie said the work will likely occur from the riverbed itself.

Using a digger on the bridge “can’t be ruled out, but wouldn’t typically be the first solution as it could damage the bridge deck and would potentially only have minimal effect when the river was in full flood”.

“Normally, it is easier, safer, and more efficient to monitor, intervening where required then addressing and removing and clearing debris once flood waters recede.”

ECan flood protection – recovery manager Shaun McCracken said an excavator had been working on the Hinds River railway bridge, and it would likely move onto the SH1 road bridge next.

ECan’s responsibility sits with the management of debris in the rest of the river, “which we’ve put huge resources into over the past two years”, McCracken said.

Meanwhile, Waka Kotahi regional relationships director James Caygill, and other key staff involved in Civil Defence emergency events will be asked about the bridge management and processes around its closure by the council at Wednesday’s meeting.

FACTBOX

Damage to the Ashburton District Council roading network from the July heavy rain event is being estimated to be around $500,000. The final figure will be presented to council in a report to submit a request to Waka Kotahi for emergency works funding.

By Jonathan Leask