The RFS was called to the tip, alongside council workers, contractors and the State Emergency Service, about 5pm on Sunday after vegetation caught alight due to heat and dryness.

RFS Canobolas Zone inspector Nils Waite said crews left the scene about 3am Monday after they were satisfied the fire was out.

However, he said flare-ups were noticed on Monday morning when crews returned to inspect the scene.

"There were a couple of areas where it popped up," he said.

Inspector Waite said crews completed a backburn around the area by about 11am to ensure there was no chance of the fire spreading outside the tip area.

He said fire crews had left the scene and council workers were mopping up on Monday afternoon.

Inspector Waite said the fire area was about 100 metres long by 30 metres wide with the piles of mulch and green waste up to 10 metres tall.

He said smoke from the fire formed part of the haze that blanketed Orange on Sunday night, along with bushfire smoke.

He said the vegetation had caught alight on its own.

"It was self-combusting due to the dryness and the heat," he said.

Inspector Waite said the fire had quickly begun smouldering and had been picked up by the wind, spreading across the area, with mounds of vegetation alight.

"We're trying to break it up and spread it out and put it out," he said on Sunday.

"We're continually pumping water and foam on it trying to put it out."