Eight members of the same family have pleaded guilty to running a complex series of illegal waste businesses from a former small-holding near St Austell.
The case at Truro Crown Court was brought by the Environment Agency and Devon and Cornwall Police.
Several thousand tonnes of waste were dumped on land at Rocks Farm, Bugle, bet-ween 2003 and 2011 after it was turned into an illegal waste transfer station and landfill.
Waste was burnt, sorted and recycled and a caravan letting business was run from the site.
Aerial photos taken in 1999 and 2009 revealed an increase in the amount of waste at the site.
The illegal station handled thousands of tonnes of waste a year.
Skips were used to import waste including soil, wood and metal for recycling or disposal by landfill on land at Rocks Farm.
Using archived data of Rocks Farm collected in April 2007 and comparing it with the results of a survey carried out in July 2011, the Environment Agency estimated that more than 4,500 cubic metres of material had been landfilled at the site.
The waste activities at Rocks Farm continued to grow despite there being no planning permission from Cornwall Council.
Nor were there the necessary permits from the Agency.
Three of the defendants, Jason and Shane Buckland and Paul Crocker, had waste carrier licences, but this only allowed them to transport waste to a licensed site.
It did not permit them to sort, treat and dispose of waste.
On June 30, 2011, police and Environment Agency officers executed a search warrant at Rocks Farm and made a number of arrests.
A court heard there was also a caravan site at Rocks Farm which consisted of some 51 caravans.
The site is not on the mains sewer and has its own septic tank system. When checked by Environment Agency officers, the system was found to be inadequate.
Additionally, it needed a permit but didn't have one.
Environment Agency spokesman Andy Gardiner said: "After a lengthy and complicated investigation jointly undertaken by the Environment Agency and Devon and Cornwall police, eight people have pleaded guilty to environmental offences and the sentencing has been adjourned for eight months."
At Truro Crown Court Leeroy Buckland, Shane Buckland, James Crocker and Karl Buckland pleaded guilty to depositing waste without a permit.
Shirley Buckland pleaded guilty to knowingly permitting the deposit of waste without a permit.
Roseanne Buckland, Jason Buckland and Paul Crocker pleaded guilty to the keeping, treating, recycling and/or disposal of waste without a permit.
These are all offences under the Environmental Protection Act 1990.
Shirley Buckland also pleaded guilty to the discharge of sewage effluent from caravans without a permit.