The folks across the street are redoing their garage door that has a drain trough in front. On Monday morning they started knocking out the concrete around the drain with a Bobcat mounted hydraulic jackhammer. The crew figured it was a 4" slab with just the drain area cut deep. Last I saw of them this afternoon (wednesday), they were still working on the 24" deep, reinforced concrete slab about 8' by 15' And from the way the hammer bounces, I'd say the grade of concrete was not the cheap stuff either!
Of course, when the other neighbor tried to remove the footings for his hot tub in a 3 season porch, the crew found out that the original builder was too cheap to put in forms for the frost footing. They just dug an 8' square hole 4' deep in the clay and filled it in with concrete. You should have seen the excavotor operator's face when he hooked the corner of that and it didn't move, didn't even shake.
I'm getting punchy from 3 days of jackhammers.