4th August 2008

The recent rains, bringing floods and landslips are a reminder that despite all the "experts", nature is unpredictable and building high density housing on hills or creating large sub-divisions where colossal areas of dirt are moved around to suit a grand design can have unforseen results affecting others.

As houses on hills have been placed ever closer to each other and being built with not one, but two or three bathrooms, the strain on stormwater systems which will often be old and cobbled together using outdated loading formulas is increasing to breaking point. Put extraordinary rain events into the mix and you have houses on the slide as has happened in Auckland and Wellington.

The new Pegasus town north of Woodend has shifted millions of tons of earth to create a golf course and housing project. Oh, it's well designed and proof of that is that it escaped any flooding in the latest deluge. Only trouble is that areas either side of it that historically have not had problems, got cut off, with roads and property totally flooded. Now that suggests someone hasn't done their homework well enough on the effects this project has on the surrounding land in unusual weather events.

Closer to home, the approaches to either side the Buxton bridge in Gore Bay have been washed away due to the flooding of the Buxton Creek and the beach has been scoured effectively blocking access to the north. Now it so happens that there is a new subdivision planned on the hill above the Gore Bay settlement. Some 87 houses are proposed on land which is composed mainly of solid clay with many stream under-runners. The storm water from this settlement is proposed to be discharged into the same Buxton Creek that failed to cope last week. One hopes that the Hurunui Council has enough expertise to gauge the effects that extraordinaire weather events may bring to bear on the existing infrastructure should such a project come to fruition. Given that the whole area is prone to slips during heavy rain, the wisdom of shifting tons of soil above an existing township may be called into question.

TC