I have seen many posts on jacking up on sagging corners on other types of Intex pools but not the ultra frame. As most know on a Ultra frame the bottom and side stick or push out far beyond the frame on top so using a jack sitting on the ground with a wood pylon going up to the top rail won't work. Two the frame is covered in vinyl liner except the very corners which only helps the corner pieces not the middle. I have three spots towards the middle where the "supposedly" compacted DG (about 5" thick)sagged when the rain season hit hard. You can clearly see the sag when you are in the pool and the pool leans down to the left as apposed to the perfectly plumb deck above it. I knew I should have paid the money and got a cement pad poured in ($3000.00 verus $350.00). Well anyway I somewhat sucessfully tried a dig underneath two pads and inserted a car jack-sized board/ and car jack under the frame's foot. I slowely jacked up 2-3 inches and was able to dig then hammer in some wood 4x4's under it, removed the jack and added/ hammered more wood blocks in the remaining hole. And it turned out okay...somewhat back to the orignal height.
Now I have 3 spots where it has also sagged (**** DG!) and 2 of them are smack against the rear yard wall and fence where the long jack + handle will not fit. i.e. 2 feet between pool side and the fence. Jacking from the side is a no no since it tweaks the frame left to right and can bend the frame/rip the vinyl.
My thought is a bottle jack but digging down 8-13 inches in virgin clay mixed with DG is a *****. Any insight how I can do this? I really wish I could use a cherry picker like some people have shown but don't se any other method than from digging and jacking from below. Your thoughts?