I have a job where I need to remove a 3' by 40 foot concrete slab that runs right along the side of a metal sided building. On the outside edge is asphalt. I want to remove the concrete and make it into a planting bed with a row of boxwoods going down it with river gravel for mulch. I don't know how thick the concrete is, probably only 4". Don't know whats under it. Would a mini ex be able to do this easily (without ruining the bucket) or do I need a jackhammer, or what? I can't damage the building (Obviously) or the asphalt on the outside edge. I wish I had a pic to show. Any ideas?