For a day's work, the men receive 10 euros (around USD 13), a half-packet of rolling tobacco and, most importantly, five cans of beer: two to start the day, two at lunch and one for after work.
"This group of chronic alcoholics was causing a nuisance in Amsterdam's Oosterpark: fights, noise, disagreeable comments to women," said Gerrie Holterman, who heads the Rainbow Foundation project, financed by the Dutch state and donations.
"The aim is to keep them occupied, to get them doing something so they no longer cause trouble at the park," she said.
The alcoholics are split into two groups of around 10 people, with each group working three days a week.
The imaginative approach to the problem of anti-social behaviour demonstrates typical Dutch pragmatism which could be found shocking in other countries, but not here.
The day begins at around 9:00 am, with the workers drinking two beers and some coffee, if desired, before going to clean the streets.
Sat at a large table, Gerrie carefully notes each person's beer consumption, but there is an atmosphere of trust: if she gets called away, the alcoholics themselves record how much they have drunk.
"I think I can speak for the group and say that if they didn't give us beers then we wouldn't come," said Frank, wearing a fluorescent street cleaner's bib and carrying a bin bag and litter-grabber.
"We need alcohol to function, that's the disadvantage of chronic alcoholism," said the 45-year-old, somewhat fatalistically.
Frank says he has been jailed for violence, has never worked for anyone and has no fixed abode.
For lunch, the team returns to the shed where they get two beers and a warm meal, before heading off again for the afternoon shift.
The working day ends with a final beer at around 3:30 pm.
"You have to see things like this: everyone benefits," said Gerrie.
"They're no longer in the park, they drink less, they eat better and they have something to keep them busy during the day."
"Heroin addicts can go to shooting galleries, so why shouldn't we also give people beer" she said.
Project participants also say they are happy to be there, all taking part voluntarily.