I installed an 18' x 33' last year. Fortunately, I have a flat yard and was able to get a contractor friend to remove and haul away the turf. I then used a long 2' x 4' and a level to make the install area dead flat. I recruited extra hands and read the instructions repeatedly. If you have any experience in construction, it is a simple process but a lot of work. I spent three days on the foundation and my pool turned out dead flat and plumb with a 1" difference in water level from low to high.
I got a great deal on the pool and saved a bunch on the install.
The critical part is to get the excavating flat. It would be wise to shore up the exposed grade with a retaining wall too. Spend the time on the foundation. The hardest thing for me to manage was the pool wall because of the size and weight but we got enough hands together and got it up.
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