Seems like Ozarkstriper knows his stuff. Since he advises no compaction within ten feet of the drip line, it's probably because roots occupy that area, and I'd leave more than that to allow for future growth. That's if the tree bears a good pecan or if you like the nut it bears.
I've read that seedling trees are more tolerant of wet conditions than grafted trees, but a seedling tree is unlikely to yield a pecan like the one you plant. Rarely, a seedling tree will bear a nut better than the nut you planted, but usually it's not as good.
Should you decide to remove the tree and plant cultivars of your choosing, your county agent would be an excellent source of information.
