We hired a backhoe excavator to dig the hole, and it was amazing how fast he whipped out all that hard clay. Well worth the money, because it would have taken us a month of sundays.
But we did the sand backfill and landscaping with "Big Silver"- our 1970's era 100hp tractor that leaks hydraulic fluid like a sieve. My husband drives, but he is blind as to what is happening on the ground- the bucket and blade block his view. I am the ground crew- I direct every motion of the bucket and blade from the ground using hand signals and a hoe. The hoe is for banging on tractor to get his attention when he is about to run me down. It has a huge diesel engine, and is so loud that he cannot hear me (that and he is half deaf- too many loud 8-track tapes in his youth).
The picture below shows the tractor being used to add back sand. The box blade is not on it in this one. It adds another six feet of length when it is.
The rock work around the pool took us a week of vacation, and other than moving piles of rock closer to the pool with the tractor, most of it was done by hand. I still have bad dreams about that.