Firefighters believe that spontaneous combustion caused a massive pile of wood at a recycling centre to go up in flames.
The blaze at the Appspond Lane base has been raging for almost three months.
Now firefighters visit the smouldering remains just once a day to check site operators are able to keep the fire under control. It should eventually burn itself out.
A spokesman for the Environment Agency said: “We are still investigating whether there are offences under the environmental legislation relating to the operator’s environmental permits and the wider impacts of the incident. We will consider enforcement action if the site is found not to be compliant with their permits.”