The firm that operates Blackbridge Farm is under investigation after failing to comply with a notice to remove illegally buried waste months ago.
The Environment Agency served the notice to Think Environmental, which operates Blackbridge Farm, near Burton Latimer, last year, demanding that the firm remove 3,000 tons of illegally stored waste by March 16.
The action was taken after the company deposited waste material on the site and covered it in soil, in contravention of its planning permission.
The Environment Agency also issued a suspension notice on the firm last year, meaning it cannot take any more waste on to its Blackbridge Farm site.
A spokesman for the agency said: “We are investigating non-compliance of the expired enforcement notice to remove the waste.
“The majority of waste has been excavated and stored under tarpaulin above ground on an area that is not permitted. Some waste has been moved and the rest is awaiting disposal at a landfill.
“We are regularly inspecting that waste pending the outcome of our investigation to make sure it is not causing a public nuisance, is not being added to and is not being moved on to the permitted site which is under a suspension notice.”
As of last month, the firm was still failing to clear the waste, and it has claimed in a county council report it does not have the money to pay for removal.Two major fires blighted local residents for days after breaking out on the site in autumn last year.
Meanwhile, enforcement action served by Northamptonshire County Council asking the firm to remove bio-dryed waste stored outside on the site has been complied with.
A spokesman said: “Think Environmental has been compliant with our enforcement notice since March and relocated the waste as required.”