Unfortunately, the plug IS iron. Or at least steel, but I'm betting iron. In any case, it's magnetic, so that rules brass out. I've been hitting it with PB Blaster and then a BFH and a cold chisel, but so far all I'm doing is putting some nice gouges in the plug and not much else. As far as finding where the pipe exits the house, that might be easier said than done. We've got a concrete porch on the front of the house and most likely it exits the house under that porch. I would imagine we could probably dig up my wife's flower bed in front of the porch and see what we can find. We have to be careful, though, because our water line comes in right about in the same area as well. About how far down would it be buried? Thanks for the pointers!