We are installing an above ground pool on a steep slope. We’re looking to put a 21-foot pool on a 25-foot circle. The 25-foot circle will have a 53-inch retaining wall on each side. One wall holds up the hill. The other wall holds the dirt on the hill. See image below.
I have a few questions.
1) How much space will we need to leave between the pool and the vertical retaining wall next to it? I spoke to a local installer and it was difficult to get answers. He said 2-feet. When I said we were going with a 2-foot pool, he said we need a 25-foot circle. 2-feet will get tight at the posts correct?
2) The installer said we need 6-inches of compacted Class 5 across the entire surface area under the pool. My retaining wall contractor says we only need 4-inches. Reading posts on the forum, it looks like people go with 6-inchs. Should we use something other than Class 5?
3) The installer said we need 6-inches of sand. Reading some posts on the forum, maybe we should skip the sand and go with a Gorilla Pad and Foam Cove?
4) The installer said we should go with a “Winter Cover” between the Class 5 and the sand. He said we need to do this to prevent the gravel from coming up through the sand and making contact with the liner. Why not skip the sand all together? Is there a difference between Class 5 and “road screenings”?
5) I see that some people add cement blocks for the rails to stand on. Do I need this or will the compacted gravel suffice?
6) Can anyone recommend an experienced installer who can answer questions that my retaining wall guy has been asking? We will of course hire the installer. I’m not impressed with the installer we talked to at the retail store. In fact, I will buy the pool elsewhere if we can get it. The 21-foot pool seems hard to find.

I have a few questions.
1) How much space will we need to leave between the pool and the vertical retaining wall next to it? I spoke to a local installer and it was difficult to get answers. He said 2-feet. When I said we were going with a 2-foot pool, he said we need a 25-foot circle. 2-feet will get tight at the posts correct?
2) The installer said we need 6-inches of compacted Class 5 across the entire surface area under the pool. My retaining wall contractor says we only need 4-inches. Reading posts on the forum, it looks like people go with 6-inchs. Should we use something other than Class 5?
3) The installer said we need 6-inches of sand. Reading some posts on the forum, maybe we should skip the sand and go with a Gorilla Pad and Foam Cove?
4) The installer said we should go with a “Winter Cover” between the Class 5 and the sand. He said we need to do this to prevent the gravel from coming up through the sand and making contact with the liner. Why not skip the sand all together? Is there a difference between Class 5 and “road screenings”?
5) I see that some people add cement blocks for the rails to stand on. Do I need this or will the compacted gravel suffice?
6) Can anyone recommend an experienced installer who can answer questions that my retaining wall guy has been asking? We will of course hire the installer. I’m not impressed with the installer we talked to at the retail store. In fact, I will buy the pool elsewhere if we can get it. The 21-foot pool seems hard to find.