First off, Chicken S. Anonymous, you should list your name and address so the city knows who's yard is flooding. Second, when rain comes down fast and hard, it takes time for the water to subside. The fake grass is not the problem. There's no violation for fake grass, that I am aware of. Someone has already complained about it, probably you, and as you can see, the city did not make them remove it. Maybe you should put in a gutter system that takes your water straight to the gutter.