Standing Patio Water
We recently purchased a house with a large, about 25 by 35 foot, solid cement patio. It is all one piece with no separations. The center seems to have settled and when it rains it pools in the center and grows algae. There is a grade on the rest of it, but it is slight, and the edge just matches the lawn where it also puddles since the surrounding land is higher.
There isn't much rain, but enough to keep it wet. I don't want to have the patio dug up to install a conventional drain, plus I don't think there is anywhere to drain it too without a pump.
I was wondering if I used an auger to bore a deep, 5 or 6 inch hole in the center of the concrete and filled it with large stones if that would drain it away. As I say, it's not a lot of water. It's just that is has no where to go.
If that might work, any idea how I can make a near circular 5 or 6" hole in the cement? I am afraid a jack hammer will crack it badly. What would I use to put in the hole to keep dirt from filling it up?
Any other suggestions for a more elegant solution?