Gale had quake-like impact on network
Damage to North Canterbury's electricity networks caused by last week's destructive windstorm is considered to be similar to that suffered during the September 2010 earthquake.
Winds gusting more than 100kmh on September 10 cut power to more than 40,000 homes in the Selwyn, Christchurch, Waimakariri, and Hurunui districts, with about 600 still without power more than a week later.
Orion chief executive Rob Jamieson said the impact of the storm, which cut power to 28,000 homes in Selwyn and Christchurch and 14,000 in the Waimakariri and Hurunui regions, was comparable to that of the magnitude-7.1 quake that hit Canterbury on September 4, 2010.
"This is the largest storm that has hit Canterbury since 1975. In terms of network damage, it is significantly larger than all other storms we have had since 1975 and only the February 2011 earthquake has had a bigger impact on Orion."
It took about three weeks to fully restore power after the 1975 windstorm, and the fact Orion had many more rural customers now showed its progress at restoring power this time was "very good", given the scale of damage.
When asked why Orion did not replace overhead powerlines with underground lines, Jamieson said the company took a balanced approach to assessing the risk of natural hazards and had determined overhead lines were the "optimal solution" for delivering power to rural areas.
"Every other network company in New Zealand has come to the same conclusion in relation to their rural networks. Cables are very expensive to install over the long distances witnessed in the rural area.
"It would likely cost well in excess of $500 million to underground the majority of our rural network and hence increased use of cables would result in large price increases to rural customers."
Orion chief operating officer John O'Donnell said all homes in Christchurch now had power back on, but about 500 homes in rural Selwyn were still without power last night.
"More contractors from throughout the South Island are arriving.
"We are throwing everything we have at this," he said.
About 100 homes remained without power north of the Waimakariri River, with MainPower crews continuing to repair tree-damaged lines and poles.
- © Fairfax NZ News
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