One thing to thing about if you use dirt from your land, you'll have a small "pond" that will be a breeding ground for misquitoes. If you make an 8' berm, you're going to have that much of a hole. Considered dirt brought in. Not cheap but you'll enjoy your backyard more without the lamps all around and the kids will also. You can put things in there to keep them out though. Let us know what you decide on. The size of the berm sounds like a large hole. Hope some of the guys from Magnolia like SGF will pipe in on what the bill will be. Be nice to go out and pop off a few rounds to blow off steam.