I had a huge play structure when the kids were little that I donated to a church camp. When they picked it up they just cut the brackets at the ground and left the concrete and 6 inch U brackets there. I am having a shed installed and there are 12 of these in the ground that I can't get out. I have tried to shovel dirt away and pry out but can barely get them to move. It was 32 feet high so they are large. Any ideas would be welcome. I don't want to get ground wet because the shed is going there but only have 2 days to get all these out and after 3 hours working on 1 figured I needed to ask for advice. It's super hard ground with roots running thru from a tree that ran thru the middle of the structure.
If they had a 32' play structure resting on top of them and they had 6" U brackets I'm guessing the footings are at least a foot in diameter? Maybe more? Keep in mind that even if you could dig the entire thing out of the ground it's going to weigh hundreds of pounds. Unless you have some heavy equipment to pull them out you're going to have some trouble moving them. There isn't any chance you can use them as a base for the shed, is there? If not, and you absolutely have to get them out, you might look into hiring an excavating contractor to do it. It's hard to make suggestions without seeing exactly what you're dealing with, but it sounds like an excessive amount of work to do by hand.
You have got your work cut out for you if you plan to do this by hand. I really would have you consider renting or hiring a backhoe or mini excavator to do this.
If you feel you really need to do this by hand, you will need to get at the minimum, an electric demolition hammer, at the most an air compressor and jack hammer. Break the concrete down about 6 to 8", and get either a right angle grinder, be VERY careful with this, or a reciprocating saw and a LOT of long metal cutting blades. this should allow you to get the metal down about 4-6" below grade.
This may still take 3 hours per hole to do, and you will still need to do a little digging.
A few ideas: - Use an engine hoist - they are usually rated to lift 4000lb when the lifting arm is in the shorted position. - Use a few $15 angle grinders from harbor freight, and a $10 diamond masonry wheel and cut some 2" grooves. Then use a sledge and a splitting wedge to break the chunks off. You might get lucky and have large splits. - Make a giant lever. A pair of 2"x10"X10' boards with one end on a flat surface next to your footing. USe steel cable or something to connect to the existing bracket maybe 18" from the end of the board. Then that gives you a bit over 8' of lever arm to lift on. This should get you a bit over 8x lifting power on the other end that you can use a hydraulic floor jack and wood blocks, or just lifting it up with a few guys. Combine it with the engine hoist and the boards will break or the footing will come out for sure!