Spot checks on builders have taken place over two days in a bid to crack down on fly-tipping in Kent.
The Environment Agency said fly-tipping costs millions each year
Last year, Swale had 8,354 fly-tipping incidents which cost the borough council more than £500,000 to clear up, the Environment Agency said.
Agency and council officers ran checks on Monday and Tuesday.
Area manager Harvey Bradshaw said fly-tipping was "a scourge on the Kent countryside" that wasted millions a year in clean-up costs.
And Alister Andrews, environmental response manager for Swale council, said anyone who created waste had "a duty of care" to ensure it was disposed of appropriately.
Builders and householders have been warned they must use registered carriers to dispose of rubbish.
Fly-tipping can lead to a court appearance and fine of up to £5,000 "just for trusting the wrong person with waste", the Environment Agency said.