I have some bull rock in my rear landscaped bed ringed with slate/flagstone. The areas in red have ponding water in heavy rains. Over time leaves have gotten between the rocks and made it easier for weeds to grow. Needless to say it's becoming overrun and I want to fix it permanently. Ideally I'd just throw mulch on top of the bull rock and add another layer of slate around the sides. Any thoughts/opinions? Post the bull rock for free to anyone who can take as much as they can?