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