Suggestions for a dog run

I have 2 more dogs than the landlord thinks I have, and we only have a dog run out the back door. I used to have a little girl here who was enterprizing enough that she earned $1 a week from about 15 people for pooperscooping. Unfortunately, her parents skipped out in the middle of the night to avoid their rent, so now I have no one.

The dog run isn't grassy, it is just dirt, with some lava rock, and shreaded mulch. The shreaded mulch is a mess, because it drags in on the dogs feet and is everywhere in the house. All the lava rock and mulch is going to go, but then i'm down to dirt. No way is grass going to grow there, so can someone suggest something to put down, that will be easier to pooper scoop, and won't drag in on the dogs feet? Sand was my first thought, but I had kids so I know how much that drags in too.