Hi, it seems that you are farther along for this tip to help you but I found the way my installers dug my pool quite ingenious. We are in an all clay area in Mich. and the installers dug the hole for the pool with a power sod cutter! they kept going around and around cutting 2" deeper each time till they hit the proper level. In my yard the end (15x30 oval) closest to the house is buried almost 18" and at the other end is a deep section. All done with a sod cutter. I never would have believed it had I not seen it. In all they hauled out 14 yds of dirt and installed the pool in 2 days. That was 14 yrs ago. Still on the same liner.
Ken