Here’s news that may not be news to anyone: city garbage collectors sometimes loaf on the job.

An investigation by the city’s Office of the Inspector General has just confirmed it, finding that sanitation crews in ten wards generally only worked about six hours of their eight-hour shifts.

Perhaps most striking about the IG’s report [PDF] are the estimates of what this kind of waste across the city ends up costing taxpayers: nearly $21 million a year in wages, benefits, gas, truck maintenance, and other inefficiencies.

The report comes a week before Mayor Daley and his staff introduce the city’s next budget, which will presumably include plans for coping with an estimated $420 million deficit.

At the same time, the mayor and Streets and Sanitation commissioner Michael Picardi have promised to continue the city’s slow rollout of curbside recycling services after dumping the expensive and ineffective Blue Bag program earlier this year. Under current city plans the new Blue Bin program would cost millions of dollars for additional staff, trucks, and other expenses.

As with previous investigations by the IG’s office, this one raises questions–never fully answered–about how and why rank-and-file workers were allowed to cheat the taxpayers. Workers report to ward superintendents, who report to higher-ups downtown and serve with the consent of the local aldermen; the people running this operation either knew this was going on or should have. As the Trib‘s Dan Mihalopoulos reports, the blame game’s already under way.

Even aside from the loafing tax paid by Chicago residents, it’s pretty clear that our waste disposal services could be provided more cheaply. Garbage trucks are staffed with three-person crews, though most other cities employ two workers per truck and many private companies just one. Trucks often return to waste transfer centers, where they dump the trash they pick up, without full loads, costing more in work hours, fuel, and wear and tear. And after initial investment, recycling should generate revenue from the sale of reusable materials and reduced landfilling bills, but in the absence of a coherent, citywide waste reduction plan Chicago’s disposal costs have continued to mount.