What is the minimum slope for a swale?

1 percent
The minimum slope for grassy swales and drainage ways is 1 percent to prevent standing water and muddy conditions. Slopes for walkways will not exceed 5 percent, unless unavoidable. Slopes greater than 5 percent may make the construction of special ramps for the disabled necessary. The maximum cross-slope is 2 percent.

How do you size a drainage swale?

When constructing a swale with known side slopes, the width of the swale can be defined in terms of the depth. For example, 3:1 side slopes on a swale indicates that for every 1 foot of depth, each side slope will be 3 feet wide, for a total swale width of 6 feet.

How do you make a homemade swale?

  1. Step 1: Evaluate the Slope. Construction of a swale begins with analyzing the slope of the yard and water runoff patterns to plan the route for the swale ditch.
  2. Step 2: Lay Out the Swale.
  3. Step 3: Excavate the Swale Ditch.
  4. Step 4: Lay Gravel and Drain Tile.
  5. Step 5: Finish the Swale.

What is a swale drain NZ?

A swale is a long, narrow earthwork that runs perpendicular to slope. They slow the flow of surface runoff and facilitate infiltration into the ground. They are perfectly level, unlike ditches, which are sloped to drain water away like a river.

How wide should a swale be?

There are no hard rules about the size of a swale, but the bigger it is the more water it can absorb during a rainstorm. Six- to 12-inches deep and 3- to 4-feet wide are typical dimensions. Smooth out the shape of the berm with a hard metal rake to form a planting bed.

How steep is a swale?

Swales are not appropriate on steep landscapes. Any area with more than a fifteen-degree slope (about 1:3.75) isn’t appropriate for installing swales, as the water saturation may cause slides, which could be dangerous.

How do you landscape a swale?

As long as you do not impede the flow of water, you can line your swale with gravel and place stepping stones along the base to create a walkway. Alternatively, in a shallow swale, you can install a durable, attractive, paving stone walkway.

How deep and wide should a swale be?

What is swale construction?

A swale is a shady spot, or a sunken or marshy place. Artificial swales are often infiltration basins, designed to manage water runoff, filter pollutants, and increase rainwater infiltration – green instances are the subterm bioswales.

What can you grow in a swale?

The bottom of the swale basin is only suitable for plants that thrive on high moisture levels, such as wetland species like reed and sedges. However, clover, most grasses, comfrey, and numerous other plants will tolerate the occasional inundation that occurs at the bottom of a swale.

What do swales look like?

For the sake of swale newbies, the basic concept of a swale on contour is to catch water as it drains and hold it in place until it absorbs into the ground. It looks a bit like a massive ditch with closed ends, trapping all of the water as opposed to having it flow anywhere.

Are swales effective?

Vegetated swales are most effective on soils that allow infiltration. If infiltration is desired, the underlying soil drainage rate should exceed 0.5 inches per hour. Drainage area and slope: Swales can be used to treat runoff from small drainage areas with up to 5 acres of impervious surface.