Normally you will commence filling immediately after you've thoroughly stripped the area of all vegetation and topsoil. The reason for this is two-fold. You'll want to protect the underlying soil from a deep freeze (a little frost won't hurt under a deep fill) and since you already have...
You have not specified what sort of aggregate that you've been filling these two sinkholes with. I think I'd recomend excavation to a depth of 6-8 feet followed by refilling w/3-4 feet of 18-24" shot rock covered w/3 feet of 4-6" cobble, topped w/2-3 feet of 1 1/2" compacted...
Regarding your intention of renting a blade (grader to most of you) sans operator (bare), I don't mean to sound overly discouraging but you must understand that a blade is a highly specialized piece of equipment.It requires more skill than any other and takes many hours of instruction and...
