Originally posted by: funboy42
I dont know what they are called but the have a engine on them and a very heavy like metal sled. It will vibrate the piss out of you. Make you hole and you use that machine to pound the ground till it is level using just a leveler.
You can't just use a plate vibrator. I just put in a 14 x 18 above ground pool in-ground by digging a big ass hole 4' deep.
My 14 x 18 pool is roughly 7000 gallons or about 280.9 lbs sq/ft A typical playe compactor weighs about 300 lbs on a 17" x 24" plate, or roughly 106 lbs per sq/ft. The water is roughly twice as heavy as the compactor.
'Undisturbed earth' in this area (illinois) will support well over 1000 lbs sq/ft. To put in the pool, you just dig until the ground is flat. That's it. Using a plate compactor doesn't do a whole heck of a lot. All it would do is push any rocks on the surface down since the weight of the compactor will be almost entirely on the rock. But you are supposed to remove them beforehand.
Besides, you are supposed to put between 2 to 4 inches of sand down along with a 4-8" cove around the edges to prevent washout. The sand is the most impotant thing to get level.
To make sure it is level, use a waterlevel as Greenman suggested. a string level will tend to compensate and be self leveling. You could be off by an inch over 20 feet and the level would still read as being 'level'. I used a 6' level first as funboy42 said, but I still ended up with a deviation of about 1/2" depensing on which direction I leveled from. the pool had to be within 1/8" or the wall would come out of the bottom.