City of Chicago leased truck leaving Reliable (3741 S. Pulaski Rd. without a tarp.-Below is a reprint of notice that Reliable Asphalt gave out to hired truck drivers.)

BY ORDER OF THE CHICAGO DEPARTMENT OF ENVIRONMENT: All trucks entering and leaving this facility must be tarped. Any truck entering this facility with materials to dump will not be allowed to dump unless the load is tarped. Any truck that is not equipped with a working tarp will not be loaded. There will be no exceptions to this rule. Trucks may remove tarps from incoming materials at the tarp rack under Pulaski Bridge. Trucks must tarp loads either at the stone piles or immediately after leaving the scale.

Looks to me like there was an exception to the rule; the trucks the city are leasing and city owned trucks. The truck above doesn't even have a tarp affixed to the trailer.