Council has developed a three-step mitigation
plan to help address the issues that has seen the repeat of localised flooding
around Totara Crescent in the Taumarunui suburb of Matapuna following heavy
rainfall events.
Executive Manager Infrastructure Vini Dutra said that the low-lying area is prone to flooding due to a number of interrelated factors including the large rural catchment above town and the design of the drainage from that.
"Following earlier flooding Council undertook a full review of the event, the contributing factors, and what works could be taken to help prevent this happening.
This saw emergency baffles installed in the culverts under SH4 and the railway to slow the flow of water off the surrounding hills.
Unfortunately, work to improve drainage on surrounding farmland and the intensity of the recent rainfall events overwhelmed the baffles, and a more substantial solution is required.
The good news is that the earlier technical assessment work undertaken by Council has allowed us to identify three simple mitigation measures we can take relatively quickly to reduce a lot of the nuisance flooding threat.
The first key step is the installation of a more robust baffle solution in the culvert under SH4 to slow down the flow of water off the surrounding hills and farmland.
The other actions include installing a larger storm water piping at the Tuku St crossing and working with KiwiRail to clear the drainage channel along that section of the main trunk line.”
Mr Dutra added that discussions with our consulting water engineer gives us confidence that these mitigation measures should be successful in preventing a lot of the nuisance flooding threat.
"We will be keeping a close eye on the impact of these solutions including undertaking further analysis to monitor and measure any residual issues.
This will allow us to understand whether further mitigation works are needed such as a new discharge path to the river, or a new storm water inlet at the Totara Crescent low point.
Unfortunately, with climate change bringing more intense weather events mitigating for them is likely to require larger and more expensive solutions," he said.
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