Q: We built a fire pit in our backyard where the previous owners had an above ground pool. I tilled the grass and covered it with stone. A couple nights ago, we had friends over and one of our friend’s chair legs fell into a hole. The hole is maybe 6-8 inches wide, but it is maybe 2′ deep.

A: Since there doesn’t seem to be any earth piled around the mouth of the hole, my best guess is the soil is subsiding where there once was a tree root, tree branch, or tree trunk that rotted underneath the original pool.

Frankly I would fill it with soil, pack it down, and be done with it.