Two fires at Calne Aggregates and the Viridor landfill site in Calne have been referred to the police as suspicious.
Firefighters from Calne and Chippenham were called to the first fire at Calne Aggregates, Abberd Lane, at 9pm on Wednesday, July 9.
They found flames coming from a single bay barn containing two skips full of general waste and used two hose reel jets to extinguish the fire.
Several cylinders were in the building, including a fire extinguisher and a butane cylinder. They were unaffected by the fire but were cooled down as a precaution.
While crews were at Calne Aggregates, emergency call handlers were alerted to a fire at the Viridor landfill site, Sand Pit Lane, at 9.45pm.
Two water pumps from Marlborough and a water carrier from Royal Wootton Bassett were sent to the site, where 1,000 tonnes of landfill waste was on fire. They fought the fire until 5.17am, hours after firefighters left Calne Aggregates at 10.43pm.
A spokesman for Wiltshire Fire and Rescue Service said: “In the Viridor fire we liaised with the Environment Agency and also Public Health England, because of the smoke, but the fire was extinguished before there was a real issue.”