I agree with those comments. If you ever plan to install concrete, then
the subgrade needs to be compacted to 95% of Standard Proctor, the fill
material should be Base Course, as we call the graded material on this
side of the pond, also at 95% Proctor. If you don't know what I'm
talking about, you should hire an engineering firm to set the grades
and inspect the work.
Expensive, yes, but cheaper than doing it all over when everything
fails in a few years.
Bugs