The floodgates are at the bottom end of the Manawatū River. Photo / Darryl Butler
The floodgates are at the bottom end of the Manawatū River. Photo / Darryl Butler
An ageing piece of infrastructure protecting communities at the bottom end of Manawatū River from flooding is tagged for a $2.5 million upgrade.
The Moutoa Floodgates - which have opened twice in the past fortnight due to heavy rain events - were originally built in 1962, on a stretch of the river between Foxton and Shannon.
When the floodgates are opened, water goes down a 10km spillway, a shortcut directly to sea. This happens whenever the water levels in Palmerston North go above 5.2m, and when levels at the floodgates are expected to go over 8.2m.
Regional council Horizons group manager catchment operations Dr Jon Roygard said the upgrades are part of future-proofing and strengthening flood protection assets to keep communities safe and increase flood resilience.
“Construction of the floodgates was completed in 1962, meaning they are more than 60 years old. Naturally, parts of them have aged since then and require replacing or upgrading to ensure they remain fit for purpose,” he said.
“These gates are a significant asset in our flood protection network. As such, we are working with contractors to ensure this work is carried out in a manner that reduces impacts to the operation of the gates.
“Replacement parts will be mostly fabricated offsite and installed in stages to help reduce impacts to gate operation.
“We anticipate up to two of the nine gates will be out of service at any one time while works are under way.”
Contractors will carry out most of the work in good weather where possible, he said.
“Due to the unpredictability and sometimes short notice of changing weather patterns, contingency plans are in place to further mitigate this risk.
“We are also finalising flood modelling to assess potential impacts of more severe flooding, and to determine necessary flood contingency plans.
“This modelling will be completed before any significant upgrade work begins that would put gates out of commission for an extended period of time.”
Meanwhile, motorists travelling over the gates during the next 12 months may experience delays while upgrade work is under way.
Traffic management will be in place, with possible lane closures between 7am-5pm on weekdays.
The contract for the mechanical upgrades was recently awarded by the council for about $2.5 million, with 75% of that provided by central government’s Kānoa – Regional Economic Development & Investment Unit.
