May 23, 2005

Papamoa East Houses Stay Dry During Devastating Flood

Eastern Papamoa's stormwater system has kept the area relatively dry compared to the rest of the flood-ravaged Bay of Plenty.

The Wairakei Stream Corridor was given it's first real test as 175mm* of water poured down in Papamoa East last week.

Tauranga City Council stormwater engineer John Palmer says a significant amount of modelling has gone into the effectiveness of the stream corridor and he's pleased with the way it performed last week.

"The Wairakei Stream Corridor is designed to become an elongated lake in the event of a flood. Water ponds into the corridor instead of on people's properties. We saw this model working perfectly during the floods, especially downstream (east) of Parton Road.

"The rain that fell in Papamoa East was equivalent to a one-in-ten year storm, but the corridor is designed to cope with a one-in-fifty year storm and would still keep water at least half a metre away from housing. For this reason we never expected any problems in the area last week," Palmer says.

Palmer says while some water built up on the western side of Parton Road, a larger culvert to be installed in the near future will see future flood levels even out through Papamoa East.

"While the larger culvert will help avoid a bottleneck situation such as the one we saw last week between Parton and Domain Roads, it won't see a huge increase in water levels downstream to Papamoa East. Flood waters will just be more evenly spread along the Wairakei Stream Corridor, which is designed to take a lot more water than it did last week."

As part of the drainage system, Council requires all houses in Papamoa East to be built at least five metres above sea level. Roads are generally constructed half a metre lower – becoming water catchment areas in times of flooding. While some roads suffered flooding in Papamoa last week, roads at the eastern end remained clear of water.

"People saw aerial photographs of Papamoa and thought the flooding was terrible on the roads, but in fact that's exactly where we hoped it would go – better there than through someone's home," Palmer says.

Palmer believes Papamoa East residents should rest easy knowing their houses are safe in the event of a major flood or another sustained downpour.

ENDS

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