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Deep cracks in Pilliga Forest caused by drought-busting rain will cost $1 million to fix

By Jessie Davies, Tuesday June 2, 2020 - 11:49 EST
ABC image
Some cracks are more than a metre wide, others are up to three metres deep. - ABC

An unusual phenomenon has destroyed access roads critical to firefighting and logging in the Pilliga Forest in western New South Wales.



After three extremely dry years, more than 500 cracks — some up to three metres deep — have appeared throughout the forest floor.

NSW National Parks Castlereagh area manager John Whittall estimated 60 per cent of the access roads in the forest's west end, near the township of Baradine, had been affected.

"We've counted 364 cracks so far, 30 to 40 access roads are impacted," Mr Whittall said.

"It's certainly a unique situation."

Fire risks heightened

The cracks posed a risk to tourists traversing the area, but, crucially, they limited firefighting activities.

"We've repaired the main thoroughfares so we can get to the key parts of the forest quickly," he said.

"We've had to use work-arounds and fix up roads where we planned to do hazard-reduction burns. Even then, we've had to be very careful when traveling."



Mr Whittall said fixing the problem was costly.

"So far we've spent $100,000 repairing roads and we expect it will cost another $900,000," he said.

The cost of repairs will be covered by insurance.

Logging industry impacted

The cracks have also caused disruptions to NSW Forestry Corporation's pine logging activities.

Forest manager Conan Rossler estimated 30,000 hectares of land — 40 per cent of its operations in the area— had been impacted.

"We've fixed cracks at 125 sites so far and have another 50 to go," he said.

On the surface the cracks appeared narrow but blew out underground to form cavernous spaces.

This, Mr Rossler said, presented a major safety hazard for his staff and the wider public.

"If you were to break through in a vehicle you could do yourself some serious damage."

Extra safety and accessibility assessments are now required before sections of forest can be harvested.



Then came the rain

The cracks appeared in March 2019 after a drought-busting deluge of rain.

A geotechnical expert employed by NSW National Parks determined they had been caused by erosion.

"The rain hit the hardened top layer of earth and then made its way into the erodible second layer," Mr Whittall said.

Mr Rossler expected more cracks to appear with each new heavy rainfall.

"It's an un-ending cycle that's going to require significant expenditure."



'Intriguing and amazing'

Tom Underwood, 83, grew up in the Pilliga in the remote sawmill village of Wooleybah.

His childhood home, in which he still lives, is surrounded by the arid forest's famous Cypress pine trees.

He said while the landscape was always changing, he had never seen so many cracks.

"There's a tremendous amount of them," Mr Underwood said.

"They're intriguing and amazing."

Last year, a major crack cut him off from the world.

"We couldn't leave our property. We had to shovel dirt into the hole to get out," he said.

"That's never happened in my lifetime."


- ABC

© ABC 2020

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