Plough confirmed as cause of massive fire
The cause of the New Zealand’s third-largest wildfire, at Pigeon Valley, has been confirmed as sparks from a disc plough.
Fire and Emergency Principal Rural Fire Officer for NelsonTasman Ian Reade said an investigation had found that the fire was accidentally sparked by an agricultural contractor using a disc plough on a rocky paddock.
The report found that sparks from metal on stone or metal on metal contact ignited dry grass in the paddock at Pigeon Valley, 30km southwest of Nelson city, on February 5. It quickly spread to a steep hillside of young pine trees.
The fire burned out of control for days, covering more than 2300 hectares of forest, property and pastures. A three-bedroom house and a shed were destroyed.
‘‘This fire proves that, in extreme weather conditions, a seemingly everyday rural activity can end up causing widespread damage,’’ Reade said.
The report by wildfire investigator Jamie Cowan said an inspection of the paddock where the fire started showed 18 significant stone strikes, some with ‘‘a significant amount of steel smeared onto the rocks’’.
‘‘I was surprised it had been disced, it was so rocky,’’ Cowan wrote.
The report said the contractor noticed smoke from an area he had ploughed about two minutes beforehand. He tried to put the fire out with the discs and an extinguisher, but it was too hot.
He had no cellphone reception in the paddock, but as he was walking out, a passerby said he had called 111.
Cowan said discing should be considered low-risk for potential ignitions in most circumstances, but in extreme fire conditions it should be subject to ‘‘trigger points’’ to identify when operations should stop.
Cowan also carried out investigations for Fire and Emergency NZ into Nelson fires that broke out during the Pigeon Valley blaze – at Rabbit Island on February 6, and at Iwa Rd in the city on February 8. He found that both had been deliberately lit.
At Iwa Rd, where the fire came close to 10 hillside homes, Cowan said the origin of the blaze was on a steep slope at the side of lower Iwa Rd, at a height where a person could have reached over the roadside fence and ignited dry grass with a lighter or other open flame.
At Rabbit Island, there were two separate fires, and Cowan again concluded that a person or persons used a lighter or other open flame to ignite the dry vegetation.
Reade said the extreme fire conditions seen last summer would become increasingly common during summer in many parts of New Zealand, particularly on the eastern seaboard.