We are finishing up our coop this week-end and the construction process has taken a toll on the ground inside the (12' x 20') run. It is basically dirt We have a huge yard and I plan to let the girls wander when we are home so they will have access to grass. Would the "girls" wear the area down to dirt anyways? Should I feel bad they they wont start out on a grassy run? Would it be a good idea to top off the run with sand and if so how deep would it need to be to keep them from getting down to the black dirt? Thanks- I appreciate all of your advice.