driveway swale

[Anonymous]

I'm looking for guidance on designing a swale detail in front of a garage that has 20' in length driveway sloping approx 15 degrees towards the garage.
Highest average rainfall in winter is 6.5-7.5" a month.
I'm getting varying answers from asphalt contractors and would like to have a formula to help figure this out. Regarding depth, width etc.
Any chance someone has something like that?
Also concerned abut cars bottoming out if swale is too deep, so trying to find the sweet spot.

[Anonymous]

Best tutorial on the subject.

http://www.youtube.com/watch?v=se5wtq2HrL4

It's in German I think, but very clear.

[Anonymous]

Thanks for the reply.
Although it shows a driveway sloping towards a garage, it does not address my main concern regarding a swale: which is volume water and size of of the swale.

[Hmooslechner]

It was my Vid. I laways try to make things better.. so i would be happy to get a hand-drawing of Your needs.

a swale should be situated at the deepest point and out of the garage, so that no water could rush in. It should be big enough to catch the water whats coming on. We in europe calculate a heavy rainstorm it with 300 liters per second per hektar(100*100m). - for 20 Minutes. So it depends on the open area, where int can rain in.

Our industry givs us tables which Diameter (DN) the swale should be dimensiond from the ammount of water.

What also can be important - what will follow with the water You are collecting with the swale. Do You have to pump it to a higher Level? Is it possible to let it direct into a river or so? Do You need an extra Generater to run the pumps in case of a shutdown-blackout?