White Knights of the South

We had been warned, but still it snuck up on us. Winter was cruising over us, situation normal, then boomfa  trouble. Big snow in the south, storms, more snow, flooding and slips in the north, power outages, bridges down. While Auckland had a major power failure due to a minor wire breaking to drop onto conductors, here down south the snow caused disarray, with widespread loss of power throughout the Canterbury Plains and the Mackenzie Basin.

Snow to these areas is not unusual but it seldom settles deeply or for long. The central plain rarely gets more than a sprinkle. Christchurch receives an erratic, short-lived dump every few years. Banks Peninsulas peaks get regular white caps or a rare big hit with a metre or so in places. Junes storm saw hardly any. Christchurchs share was 10 to 50 millimetres of wet snow that did little damage and was mostly gone in a couple of days. Hard frosts that followed kept patches frozen in the shade.

Up country, things were different. The plains rise from 10 to 20 metres at the coastal cliffs to about 450 at the base of the foothills on the western fringe. Snow depth and the time it remained reflected that gradient. In general terms, preparedness also mirrored it  there is often snow near the hills but seldom any in the middle or near the sea. This years storm blanketed the whole plain, and almost the whole island.

Coverage elsewhere varied and in Otago, where they are better prepared, it was mainly a traffic issue. Canterbury was caught out, but advised to stay in.

Major job for repair crews

Outside was the domain of the repair crews. Snow-laden HV feeder lines came down. Poles broke due to the weight of snow on the lines. Connections were torn from buildings. Trees and branches fell across lines. Farm building roofs collapsed. Wires stretched. Insulators broke.

Initially, road access was limited as the snow depth over a vast area was above the practical limit of a 4WD ute, even with chains. In many places it was much deeper than that, peaking at about a metre. Snow-plough crews were promptly on the case, clearing main routes and liaising with power companies and councils to open access to critical spots. Every available plough truck, grader and loader was out pushing snow and clearing debris from roads.

A week after the big fall I drove west from Christchurch via Hororata to the Rakaia Gorge bridge, then south to Geraldine and returned via Temuka and Ashburton. There was little sign of snow before Hororata where paddocks become uniformly white and patches of snow lay on roofs and buildings. Coverage thickened as I approached the hills then suddenly vanished in the lower area of the gorge. Once back up on the plateau near Mount Hutt, a continuous blanket of snow ran to the horizon in each direction. It had compacted to a depth of 300400mm with a crunchy crust that could be walked on. One paddock in every six had deep, looping tyre tracks from feeding-out.

By now, power had been restored to most places and subscribers. Almost all roads were clear but there was little traffic.

Rivers and creeks north of the Rangitata were up slightly but still clear  a sign of very slow thaw. Further south they ran dirty and high from a more active melt. Damage to trees was evident everywhere. Firs and gums were worst hit  small firs had simply fallen or leaned, mature ones lost whole branches, often across powerlines. Every gum tree was corralled by a circle of its own debris, some of which had also damaged lines, poles and buildings. Huge branches had been pushed to the road verge.

A dearth of coffee outlets

By late morning, needing a coffee, I aimed for the Staveley Store. There was a foot of snow on the roof and outdoor tables, and a sign on the door saying Sorry, closed, no power.

Next stop south was Mt. Somers. The store there was open. Theyd been sans power for about three days with reconnection a priority in order to get the fuel pumps back on. Their coffee machine was down though, so parked in ankle deep snow by a stone hut, I was forced to fire up my gas cooker. Perfectly clear blue sky, no wind, no sound except for birds. Gorgeous, in fact, although perhaps not for the line crews who put in 12-hour-days replacing broken power poles or re-rigging crossbars, insulators and wires with stiff, cold hands. As far as I could see, everything was white.

Many properties were without power still as crews moved from repairing major feeds to the more minor and isolated problems. Repair priorities are well documented and planned. HV lines and substations are first on the list. All feeder lines from subs must be inspected before being repowered.

Damage to lines was widespread, though often minor. The snow from this storm was very wet and sticky, building up quickly on wires and stretching them or pulling down poles. About half of the damage was due to falling trees or branches. Line crews isolated such sections and returned to repair them after they were cleared by arborist teams. At least 500 poles were replaced.

Soggy ground delays vehicle access

About 35,000 businesses and homes lost power and the last were reconnected about three weeks after the event. These later ones were low priority cases such as irrigation pumps not needed in the winter, sheds, barns, baches or unoccupied houses. Some were delayed by poor vehicle access across soggy ground during the thaw.

Electricians with relevant tickets were contracted to accompany line crews to assist with property reconnection. Repair policy in such conditions is to not have crews working up poles in the dark. Better to have them get a good break and be fresh for the next and subsequent days. Tired people are more accident-prone. In favourable conditions power lines can be repaired while live. Fully insulated rubber gear is worn but it is too time-consuming for emergency repairs and not an option in bad weather.

As Stu Kilduff of Orion pointed out, when power is lost through storm most people are aware therell be a delay before its back on. They gear up to cook on the wood-burner or barbeque, and dig out the candles. What they really want to know is, how long will they have to do this? They need to plan, cut firewood or, in some cases, go out and buy a generator. Orion published daily updated maps of affected properties. Some wood-burners were unable to be used as their wetbacks needed the water pump running to supply flow.

New Zealand houses have water pipes in the outer walls which makes them vulnerable to freezing, especially if the house is not heated. Places like Canada put their pipes in internal walls for this reason. Plumbers were also busy after the snow.

Second dump not as bad as the first

There was a second snowfall about a week after the first. It was not as serious but did lay fresh snow over that which remained. Great fun for a snow-ball session but spare a thought for those repair crews out there working up poles in the wind and driving snow, turning nuts with heavy, cold wrenches or twisting fat wires with pliers and stiff, soggy, leather gloves. No room for mistakes as a result of being tired, hungry or cold.

Trudging uphill through knee-deep snow carrying a ladder and tools to re-connect a farm house; digging laden utes out of snow-drifts or a boggy paddock in the thaw  which they did for 12-hour sessions, day after day, with no shops to buy lunch or warm cafs to sit in for a quick cuppa. Munching their sandwiches while cramped in the cab of a truck with cold wet snow dripping off the bulky wet-weather gear and steaming up the windows. The word heroes comes to mind.

Good on ya, guys!