The NSW Environment Protection Authority is monitoring the clean-up of an industrial site at Hexham, after firefighters spent most of Sunday battling a blaze that broke out in a large scrap heap.
Twenty fire crews from 11 stations raced to the Maitland Road site in the late morning to fight the blaze, which spewed black smoke into the air across nearby suburbs.
An EPA spokesperson said on Monday that the smoke plume had dissipated and all firewater was contained to the site - most had been removed to a facility legally able to treat that kind of wastewater.
"The EPA attended the site [on Sunday] and will continue to monitor clean-up at the premises, which is regulated under an EPA Environment Protection License," the spokesperson said.