I too am going to see if I can reignite this old thread.
I just setup my new 15'x48" Intex Metal Frame pool yesterday.
To prepare the area for the pool I had to dig up the ground that was sloped to make it flat; I basically carved out a giant 17' x 17' square in our slopped backyard. I then had to put up retaining wall bricks around the walls so that the dirt wouldn't wash down over time. So far so good; it looks mostly flat (for regular ol' dirt) and the retaining wall is in place.
The ground around the edges isn't as hard and compact as the center dirt. To lay down the retaining wall bricks, I had to dig up a trench for the bricks to sit in, then fill it back up with dirt and tamp.
Now a few of the legs are already starting to sink into the dirt and I've just had the pool filled for one day.
I'm in LA where we're experiencing an EXTREME DROUGHT, so I don't want to empty 4,400 gallons of water and "try again".
Maybe it'll be fine? The legs that are sinking aren't extremely low in the ground; maybe an inch or two at the most?
It's also making the pool slightly uneven, where the sinking side is a couple inches lower (and thus the water is almost to the edge of the pool).