We are wanting to get an above ground pool that is approx 20'w x52"deep. Our yard is not really level enough to use so we are thinking we could possibly set it up in our driveway. It seems level to the eye but of course it is sloped enough to allow water to drain to the back yard. Is there some kind of platform that could be built or what do you suggest??
You won't be able to (economically) build a platform to set the pool on -- water weighs a lot! Supposing that pool is round and 20 feet diameter, when filled to 50" depth it would contain about 9800 gallons and weigh almost 82000 pounds. A truckload of sand leveled on top of the driveway is probably the only way you'd make a "platform" to support this weight.
Figure out just how out-of-level your driveway actually is by constructing a water level. You'll need a garden hose and a bucket. Using the hose, fill the bucket with water. When it is full, keeping the hose end immersed in the water at all times, disconnect the hose from the faucet and carry the bucket to the high end of the driveway. Carry the disconnected end of the hose to the low end of the driveway. Slowly move that end of the hose vertically, up and down until you see the water inside rise up to the mouth of the hose without spilling over. Finally, measure the height of the water in the bucket (above the driveway surface) and the height of the water in the mouth of the hose. The difference in these two figures is the difference in elevation across the driveway.
If the slope is only a few inches you can probably just set up the pool out of level and it'll be fine. One side of the pool just won't be as deep as the other. I'm not sure how steep is too steep, but I can tell you that I set up my own above ground pool maybe 2 inches out of level and everything worked out fine.
One other thing.. I don't mean to be a wet blanket, but consider safety. You don't want neighbor kids coming along, sneaking into the pool, and having an accident (drowning, for example). You may be taking a big risk in erecting a pool outside of a fenced yard.
I use sand , if you don’t mind killing the grass the same can be used in your yard with some railroad ties, put a tarp over the sand so it doesn’t wash out and it can last for a long time , usually tall pools are left up. I will also put a tarp down on the asphalt to protect the liner it will last longer if not in direct contact with the asphalt. And if gophers dig under if in a yard the tarp helps to protect the liner there also.
First I mark the area and use a transit or laser level to provide the needed fill, if I need 4” a 4x4 , 8” a railroad tie and backfill the area with sand staple the tarp to the wood or roll the tarp 1 turn , verify the area is flat prior to setting up the pool. If using a single point laser level shoot from both sides to verify the level is true a slight deviation you would not see in 3’ can turn into your pool is 3” lower at one end, by checking both directions you eliminate any errors.