"It's a long, laborious process," Wenita planning superintendent Paul Greaves said at the fire site yesterday.
"These guys have been here day after day doing this.
"It's relentless, but we have to.
"Any one of these hot spots could start it all again."
Staff who would normally prune or thin pine trees had chipped away at the remainder of massive piles of smouldering slush (branches and wood waste) with hoses and shovels for nearly three weeks.
It was slow, dry and dusty work and, while they were making progress, the wind was not helping, time and again fanning deep-rooted embers back into life, Mr Greaves said.
This week, ditchdiggers were being used to dig out embers buried metres deep, while Wenita crews hosed them down with water.
Workers Jerreau Harris and Greg Warrington said it was not so bad now they were no longer digging.
The worst thing was the wind and dust.
Dozens of hot spots had already been tackled, with those most likely to cause further problems seen to first.
The biggest underground fires took days to extinguish, with some costing up to $30,000 to put out, Mr Greaves said.
The wind was their biggest enemy.
At the weekend, for example, gale-force winds set hot spots over much of the site smouldering again, requiring crews to work through the day and night.
Contractor Darrin Kealey said although the fire was mostly out, the danger it still presented was demonstrated on Saturday when a single ember flew into the hydraulic system of a ditchdigger, causing it to burst into flames.
The driver escaped uninjured, but the ditchdigger was badly damaged.
Mr Greaves said a flyover with an infra-red camera on Sunday had detected some hot spots on the boundary of the fire site, and ground crews spent yesterday seeking them out using heat sensors.
What was needed was rain, Mr Greaves said.
