Canterbury better prepared for wind

01:40, Sep 01 2014
Harry Meijer
STORM CASUALTY: Canterbury farmer Harry Meijer's centre pivot irrigator was blown over the gales of September 17.

Almost a year on from the windstorm that flattened pine plantations, tipped over irrigators and ripped roofs off countless buildings, most of the damage in rural Canterbury has been repaired and about an extra 300,000 cubic metres of timber has been exported to China.

The worst winds in Canterbury since 1975 struck on the evening of September 10, with a recordsetting 251.9kmh recorded on Mt Hutt. Just over a month later another norwest gale blew in, just as devastating as the first.

Irrigation New Zealand estimates 800 irrigators were damaged, with many centre pivots flipped upside down, the resulting damage taking months to repair and costing millions of dollars.

The largest rural insurer, FMG, with about 40 per cent of the market, has settled 271 claims, at a cost of $7 million.

Co-owner of Plains Irrigators Liz Stephens said her company came up with a strategic plan after the windstorm, getting partdamaged machines back in action first, albeit at a reduced capacity, and then concentrating on clients whose pivots had been totalled.

''It's devastating for our clients and our staff not to be able to go out and fix everybody's in the first week. Our staff found that particularly difficult, saying to people, 'It's going to be three months but we will come and take off the broken bits so at least you can water with three or four spans'.'' The most vulnerable parts of centre pivots are at the outer end.

The overhangs, that can spread the water an extra 60 metres as the machine goes round, are relatively easily damaged and also at risk are what are called corners.

''Usually a centre pivot just goes round in a circle but in New Zealand, because land is worth money and there's lot of water, we do the corners and we have these funny corner arms that walk in and out.

There's quite a lot of risk associated with them from a wind perspective,'' said Irrigation New Zealand chief executive Andrew Curtis.

Even when the pivot is parked parallel to the wind, as is recommended practice in big winds, the overhangs and corners can still catch the breeze. As well as sustaining damage themselves, the battering many suffered also placed stress on the rest of the machine, leading to more destruction.

To get irrigators back in action as fast as possible Plains Irrigators removed many overhangs and corners and capped the end of the pivot so at least it could still water part of the pasture usually covered.

''The machines had gone round watering pretty well without them and we went back and had them completed mostly in March this year,'' said Stephens.

Burnt Hill, North Canterbury, dairy farmer Harry Meijer lost power in the gales but within 24 hours he was sharing a generator with a neighbour. His centre pivot, which was being used for effluent, was tipped upside down.

''I'd like to think we're a wee bit smarter in how we think about things now. Having said that, many of us still put our effluent out through the pivot and even when there's a warning, we might only have 12 to 24 hours' notice.

Those pivots walk awfully slowly and we've really got to be on the ball if we want to have our pivots in a safe direction.

''Our pivot takes two-and-a-half days to do a full round so if we're a quarter of a round out, say, so we're at right angles to the wind, it's the thick end of two thirds of a day to get to a wind-safe direction.''

Meijer has increased his effluent storage and all his staff have been brought up to speed with the farm's backup travelling effluent irrigator, so that if there's another wind event that puts the centre pivot out of action he won't have to worry about what to do with his effluent.

''A two-man team can have it going within half an hour. It's future-proofing things, if you like,'' he said.

While some farms were without irrigation water for months, the worst of the effects were moderated by a cooler, wetter summer than usual in Canterbury. That cool weather is also thought to have helped keep felled pines in good enough condition for harvesting.

''It's been quite extraordinary that we're still harvesting. We're getting very little deterioration or losses as a consequence of heavy sap stain,'' said forestry consultant and marketer Alan Laurie.

After the winds, it was generally expected the trees would last about three months, but not far into the new year.

''Heat and moisture together are what will induce heavier sap stain but the wetter period may have just elevated the root growth beyond the norm. It's hard to say – there could be a range of factors – but I suspect the wetter conditions would have helped.'' Laurie said the post-storm cleanup was nearly finished, with the windblow harvest boosting Canterbury's annual cut from about 700,000 cubic metres to more than a million.

''Big companies like Rayonier would have just kept chugging along with a similar cut programme and didn't really take on additional resources.

The privateers like ourselves were probably the ones that ramped up the volume.'' Midway through the cleanup, log prices crashed 30 per cent, but Laurie said the market was now recovering.