Your fill should probably be more gravel or coarse sand. As far as footings for the edge of the slab, just thicken the slab to 8" to a foot deep. Or you could use a separate footer of the dimensions you mentioned. A thicker slab at the edge where you'll drive off will help prevent it from cracking. You could ask some "hypothetical" questions for a "friend" of the building department in the nearest city.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.