Natural Resources Wales is working with agencies to advise and monitor the impact of the fire.
Huwel Manley from Natural Resources Wales, said:
“We are working with the fire service and other agencies to advise and monitor the impact of this fire.
“It’s important that we keep communities and the environment safe from harm and pollution, and fires such as these can affect local air quality and pollute rivers.
“We regularly take enforcement action against individuals and businesses who pollute and damage the environment and we have been concerned about this site for some time.
“We recently prosecuted the previous occupiers of the site in respect of this illegally stored waste and had already started the process of using our statutory powers to require its removal from the site.”