Installing a 24' round AGP...

[matt4x4]

I built a pad for my pool since I built it on a low spot on my property and needed to get it higher than the creek right next to it since the creek sometimes crests the banks.
The pad is about 1.5-2 feet thick at it's highest location, it is made of whatever pile of dirt I had kicking around - probably clay since everything here is clay!
On top of that I used stone dust to complete levelling the pool - the pad wintered for one season before I started building, however I believe the same compaction could easily be achieve using the right equipment.
I really don't think you have anyhting to worry about.

Pool manufacturers highly warn against it since AG pools are generally designed with "self install" in mind, I believe the manufacturers want to avoid unnecessary attempted warranty claims because if Joe Spadeandrake were to do it, he likely won't compact it properly causing early structural failure.

[CarlD]

You can build up, I did. It's a LOT more expensive than digging down. I recommend that you have the outer wall of the build-up re-inforced with a retaining wall. Use stone/block, not railroad ties.

Here's a familiar picture of mine--you can see the rows of block. Rather than rock dust, we used QP--Quarry Product, similar to crushed stone but not washed of the dirt. Packs like iron.