Drainage swales are shallow-sided, sloped channels intended for the conveyance of surface runoff. They are located between or around buildings and are graded to intercept and convey surface runoff to the nearest on-site catch basin, preventing lot-to-lot drainage.
Minimum Swale Slope Requirements
The minimum slope for a swale depends on the surface.
- Grass drainage swale: 1.5%
- Concrete drainage swale: 0.75%
For other requirements for swales, refer to the lot grading drawings page.
Example Swales
-
Concrete Swale on an Industrial Property -
Parking Lot with a Swale Towards the Catch Basin -
Concrete Surface Sloping Towards a Catch Basin -
Swale on Apartment Site -
Graded to Catchbasin -
Grass Swale -
Internal Swale -
Concrete Swale -
On-site Concrete Swale -
Grass Swale at an Apartment Sloped to Catch Basin