So your discription of your location... I'm interpreting it as, there is concrete with a path of a few inches of dirt that runs the length of the concrete? Is there any way you could post a photo of your location? Ive got this idea in my head, but it wouldn't work if the dirt doesnt run the length of the concrete that your coop and run will cover...
Anyways... "IF" the dirt strip runs the length of the concrete. You could always dig the dirt out 6 inches or so, to creat a trench. "make sure the drainage trench is longer than your run, to move the water away." Fill the trench with gravle, lay a strip of landscaping fabric over the gravle, "to keep sand out of gravle." and then layer in your sand. The trench filled with gravle would give excess water a place to drain, thus minimising any standing water in your run. It would be a basic curtain drain.
I live in NW Washington, so I understand what you mean by rain. This basic set up is what I use around my buildings, yards, and in my horses padocks to reduce any mud, or standing water. And it has worked well for me.
I don't know if I typed this in a manner than anyone but myself can understand. lol But it reads clear to me!
Anyways... "IF" the dirt strip runs the length of the concrete. You could always dig the dirt out 6 inches or so, to creat a trench. "make sure the drainage trench is longer than your run, to move the water away." Fill the trench with gravle, lay a strip of landscaping fabric over the gravle, "to keep sand out of gravle." and then layer in your sand. The trench filled with gravle would give excess water a place to drain, thus minimising any standing water in your run. It would be a basic curtain drain.
I live in NW Washington, so I understand what you mean by rain. This basic set up is what I use around my buildings, yards, and in my horses padocks to reduce any mud, or standing water. And it has worked well for me.
I don't know if I typed this in a manner than anyone but myself can understand. lol But it reads clear to me!