Flooding fix gradual
Freak summer flooding two weeks ago might have caused residents to despair at Porirua’s stormwater upgrade programme but improvements are coming, says Porirua City Council.
Pukaki Gr in Waitangirua and Semple St in the MegaCentre were under water on the night of February 4 after a oncein-30-year rainstorm battered Wellington.
But some of Porirua’s worst flooding spots are having nearly $ 700,000 spent on them this financial year, says Peter Bailey, the council’s general manager of asset management and operations.
The 10-year budget for stormwater upgrades is $4 million.
Pukaki Gr’s flooding was caused by plastic bottles blocking the cul-de-sac’s drains, Mr Bailey says. The council is installing grates over many of the city’s sumps, or entrances to drains, to stop flooding and prevent rubbish flowing to the harbour, he says. The grates will soon be installed in Pukaki Gr.
However, full stormwater pipe and sump upgrades are limited this year for areas where there is a greater risk of water entering houses and businesses, Mr Bailey says.
Other problem areas will be addressed in coming years.
Porirua’s stormwater issues stem from ageing pipes that can’t handle present volumes of water, and not enough sumps to let the water in. Upgrades will involve a total redesign of pipe networks based on flow volumes, larger pipes, and increased sumps, Mr Bailey says.
However, flooding will never completely disappear. Stormwater pipes are designed to cope with a one-in-10-year event, so streets would still flood in a larger event like on February 4, Mr Bailey says.
Also, houses built on low-lying areas across the city are simply prone to flooding in major downpours, especially if they have lots of concrete fill-in on their sections, he says.