You've got it greene! Your daughter in effect already has a rain garden. You just need to help her make it a garden. Sounds like it might be a great spot for some Cannas and gingers, too, if there's any sun available?
Deb, on the "permeous" spelling issue, I think it must be either porous or permeable. (but we knew what you meant) Whipped concrete (with bubbles and spaces) for walkways, ungrouted pavers and bricks, gravel and shell driveways etc. are very common down here - it's known as 'porous paving' and is strongly recommended for preventing storm water runoff, same as where you are. Except, when it rains, it rains harder here, trust me. None of that dribbling and dripping for days on end. More like standing under a fire hose blast. (I'm originally from Vancouver BC, btw)
Rain gardens, on the other hand, are not so common, although there are a lot of drainage ponds and water gardens that have water all the time. The land is very flat, and we are virtually a desert for nearly 8 months of the year. It only rains dependably from June through September. (although of course this year . . .
we had a wet May and so far no rain in June to speak of).
