The cost of a three-day stay by Travellers in Gunnersbury Park was today estimated at £18,000 by Hounslow Council, which must foot the bill.
That is how much it believes extra security at the site, legal fees and the clean-up operation will end up costing council taxpayers.
The clean-up began this morning as the park reopened to the public, having been closed yesterday just before 5pm due to safety fears.
As well as clearing piles of rubbish from the grounds, they are left with the task of repairing damage the vehicles have caused to the turf.
Among those who turned up at the park last night only to find it closed to the public were Vladimir Petkovic and Ljubomir Radanovic, who play friendly five-a-side football there every Wednesday.
"It's a shame that nobody can use the park while they're there. It's ridiculous that in the 21st century you can have this kind of living," said Mr Petkovic.
Although there was also a lot of criticism on Facebook of the Travellers' behaviour, there were also some sympathetic voices.
Eric Blend Lynx Almeida said on the social networking site: "Let them stay and it's a free country and you can't you can't tell them what to do."
Travellers arrived at the site on Sunday and left last night, heading to nearby Blondin Park.
