‘We need every chopper possible’

Report reveals how tractor working tinder-dry paddock sparked February’s devastating blaze in Pigeon Valley

On a scorching, cloudless summer’s day, a disaster was in the making. A tractor driver ploughs a stony, tinder-dry paddock while the mercury tops 28C. Tall, parched grass. A blustery wind with low humidity and an “extreme” fire danger.

The result was a “Swiss cheese effect”, where all of the holes align, and the sparking of New Zealand’s largest wildfire in more than 70 years.

February’s great Pigeon Valley blaze, 30km south of Nelson, would burn out of control for days across 35km, destroy or damage 2300ha of pine forest, raze a three-bedroom home, multiple outbuildings, fences, shelter belts, pastures, and cause the evacuation of a town of about 2500.

A final report into the origin and cause of the fire, released yesterday, reveals for the first time how the contractor’s disc plough had struck stones at least 18 times before the fatal spark. Newly released photos show rocky, charred ground that looks more like a riverbed than a paddock.

And yet, it’s been declared an unfortunate accident.

“This fire proves that, in extreme weather conditions, a seemingly everyday rural activity can end up causing widespread damage,” said the principal rural fire officer for Nelson-Tasman, Ian Reade. “It was the proverbial perfect storm.”

The investigation begins

Jamie Cowan got the call about 7pm on February 5. There’d been a big fire start up near Nelson and would the Queenstown-based experienced wildfire expert, who worked on the 2016 Port Hills fires, investigate? He was on his way. Hydraulic technician Joel Scott was driving back from the forestry block on Pigeon Valley Rd that afternoon when he spotted leaping flames.

Ditching his ute in the middle of the road, he ran towards the fire and made the first 111 call. “We’re going to need a chopper real fast,” he told the call operator at 2.14pm.

Scott took the first photo of the inferno and approached a “flustered” man at the scene.

It turned out he was the tractor driver. He’d tried to phone 111 himself but couldn’t get a cellphone signal and was watching on helpless.

He’d been discing — towing a plough behind a large Fendt tractor — since early that morning on land leased by local farmer Ian Parkes.

After churning over several neighbouring paddocks, the contractor had started on the stony area near a creek.

Scouring the scorched earth, Cowan found multiple “strike marks” on rocks where the metal discs had passed. Often, metal had been “smeared” on to the rocks.

There were 18 “significant stone strikes” found in total. Magnet tests around the strikes showed lots of metallic filings and particles.

Later, when the contracting company boss was asked how common it was for the plough’s “scrapers” — metal blades which keep the discs free of debris — to come into contact with the discs when going over rough ground, he replied, “Very common”.

The tractor driver told Cowan he’d been discing for just a few minutes when he noticed smoke coming from an area he’d just ploughed “around two minutes before”.

He desperately tried to put the fire out by discing over it. When that didn’t work, he grabbed a fire extinguisher. But by then, the fire was too hot and growing every second.

Scott said within minutes, fuelled by southerly winds, it had gone from “the size of a barbecue fire” to galloping up and over a steep and recently harvested hillside of forestry, into a vast plantation block.

The Wakefield Volunteer Fire Brigade was alerted to a vegetation fire at 2.16pm, according to the Fire and Emergency SMS incident report released to the Herald under the Official Information Act. Brightwater units were roused about the same time.

“I suggest they get every helicopter they can”

Firefighters were there by 2.34pm.

And the emergency calls kept coming — 13 in 22 minutes. There would be 27 in total.

The first helicopter arrived at 2.40pm, says Fire and Emergency NZ (Fenz). Two more came at 2.45pm.

But the blaze was already out of control. “I suggest they get every helicopter they can get their hands on, now,” said a frantic Brightwater farmer calling 111 at 2.48pm.

By 6.33pm it was “uncontained”, with five helicopters working on it.

Residents in Eves Valley and Teapot Valley were being evacuated.

One farmer at Redwood Valley lost more than 60 sheep. “It was pretty horrible, to say the least,” said agricultural contractor, TB tester and part-time farmer Steve German.

That afternoon the Redwood Valley fire was contained around homes.

Sixteen aircraft were available for the aerial assault. Six more were available by day two, with two fixedwing aircraft dropping fire-retardant.

In following days 61 units from across the country were scrambled for the biggest aerial firefighting operation in New Zealand’s history.

The blaze spread across 2316ha, spanning 36.4km — more than the 2017 Port Hills fires in Christchurch.

After 22 days, Civil Defence lifted the state of emergency.

The findings

On the second day of his probe, Cowan and a mechanic took a look at the tractor and disc plough.

They couldn’t find any obvious damage or mechanical faults and work logs and maintenance records stacked up. Cowan didn’t find any birds’ nests or grass under the bonnet which could have ignited either.

The contracting firm owner confirmed his driver didn’t smoke, and no cigarettes were found at the scene. Nor was there evidence of other fires, lightning strikes, powerlines problems or traces of arson.

Cowan decided it was most likely that the discs struck a stone or rubbed on the scrapers, and “resulted in a spark[s] or a hot surface that has contacted and ignited the fine fuels”.

He concluded the fire should be classified as “accidental” and caused by “equipment use”.

“I am confident this fire was caused by the operation of the discs in very stony ground on a hot, very dry windy day,” Cowan said.

“To determine if it was a spark from the disc or scraper, or the hot surface created when the disc and scraper have come together is a question I cannot answer. I believe this report has proven both to be competent ignition sources. Combined with the ‘Swiss cheese effect’ of perfect weather and fuel conditions, a fire from a source not historically considered a fire risk has occurred.”

Police last month said they had not pursued any criminal charges.

An independent review into Fenz’s response to the Tasman fires, which includes the likely deliberately lit Atawhai and Rabbit Island blazes, is ongoing. Fenz hopes to publicly release its findings in October.

A spokesman said Fenz will review today’s findings in coming months to decide if more action is needed.

Insurance Council chief executive Tim Grafton said while he did not know how insurers will respond to Pigeon Valley, in general terms insurers reserve the right to “pursue recovery from at fault parties and/or their insurers”.

Cowan concludes his report with some recommendations on how to prevent future disasters.

While discing should be considered “a low risk for potential ignitions in most circumstances”, when done under extreme fire conditions it should be subject to best practice “trigger points” like those used in the forestry industry.

Other basic precautions, Cowan said, should include discing a break around the outside of a paddock to prevent fire spread if an ignition does occur, discing rocky ground in the morning and having larger fire extinguishers or another portable water source on hand during extreme fire days. Further mitigation could include modifying discs so scrapers cannot contact the discs or manufacturing them out of a different compound that will not cause sparks.