A drainage swale costs $0.50 to $1.00 per square foot or $5 to $15 per linear foot, depending on the size, depth, and grading required. A swale or irrigation ditch slows and controls the flow of storm water runoff by grading a sloped channel into the lawn. The surface may be grass, vegetation, or crushed stone.
Affordable: The average cost to build a swale drainage ranges from $0.50 to $1 per square foot or $5 to $15 per linear square foot, making this drain type one of the most affordable to install. Aesthetic appearance: Due to their inconspicuous appearance, swale drains can easily fit into your landscaping plans.
Designed water depth - The swale should be designed to hold the first 1 inch of runoff from the contributing drainage area and be a minimum depth of 12 inches (see Figure 1).
A swale is best for managing surface water over large, open areas, and is ideal for settings where a natural look is preferred. A French drain is going to be better for subsurface water issues, particularly where groundwater is a problem or you need to protect foundations from water damage.
A drainage swale costs $0.50 to $1.00 per square foot or $5 to $15 per linear foot, depending on the size, depth, and grading required. A swale or irrigation ditch slows and controls the flow of storm water runoff by grading a sloped channel into the lawn. The surface may be grass, vegetation, or crushed stone.
The primary function is to convey stormwater runoff and there is minimal water quality benefit; however, rock lined and vegetated swales may decrease the velocity of water and facilitate some infiltration. Vegetated swales may have the added benefit of filtering stormwater as it flows through the swale.
When should you not use a contour swale? Contour swales are not the tool you want to choose when the issue you are facing is too much water and oversaturation on your site. They are also best used on slopes that are 3:1 or less because that keeps your berm from getting too steep, causing further erosion.
0.5% is plenty for a concrete swale, I'd argue you could get away with 0.3%. My local jurisdiction is general fine with that. For concrete sheet flow I would say 0.5% is a bare minimum but ideally you're closer to 1%.
Reseed bare areas to avoid erosion. Be sure to water during the initial establishment period. Inspect and maintain or repair components. After rainfall, check the swale to ensure the water does not pond longer than 2 or 3 days after a rain storm.
If installing the drain involves diverting a stream or affecting a wetland, you likely need a permit to move forward. Generally, a small French drain on your property that doesn't change the flow of runoff entering and exiting your yard won't need a permit.
Interior French drains are meant for waterproofing the basement or draining your crawl space. They cost more because contractors must tear out the basement floor (most often made of concrete), install the drain, and then repair it.
An alternative to the French drain, the NDS EZ-Drain installs without gravel, saving a lot of time and money. EZ-Drain bundles consist of fabric, lightweight gravel substitute, and pipe. It's like an entire yard drainage system, bundled neatly together.
The swale cross section should be trapezoidal in shape. The steepest permissible side slope of the swale should be 2:1 (Horizontal: Vertical).
If you have a drainage swale on your property, it's your responsibility to maintain it so that it functions properly. Improperly maintained drainage swales interferes with proper drainage flows that can result in property damage caused by slope failure, erosion, or excess storm-water runoff.
The HRT of a swale can be calculated using the following formula: HRT = L / 60V (1) Where: HRT= Hydraulic Residence Time (mins); L = Swale Length (m); and V = Flow Velocity (m/s).
Dig a level trench.
The trench can be as deep as you need - 1' is about average, less if you don't plan on filling it in with anything.
One option is to reslope the soil surrounding the area, allowing for proper drainage. Another option is to install a French drain, which will redirect the excess water away from your concrete surface.
Place rocks, gravel, mulch, and/or plants within the swale. Test the effectiveness of the swale by running water through your system.
Swales can slightly reduce impervious area and reduce the pollutant accumulation and delivery associated with curbs and gutters. Disadvantages of this technique include the possibility of erosion and channelization over time and the need for more right-of-way as compared to a storm drain system.
The uphill side of the house must have a drainage waterway (swale) to direct the water around the house. This drainage swale should be at least ten feet from the house and sloped to convey accumulated water away from the dwelling efficiently, and into a proper outlet.
Definitions: Swale: A trench dug into the soil, following contour lines, to help capture runoff and the topsoil that it carries. Berm: A mound of dirt, stone, or other debris laid out following contour lines to slow the movement of water and soil.
A swale is a gentle trench that slopes down and away from a home's foundation. With the trench in place, fill the swale with river rock and then line the edges with pea gravel to create an efficient and attractive water diverter.
A lined swale is used to convey concentrated runoff to a stable outlet in situations where a grass swale is inadequate. A lined swale can be lined with concrete, manufactured concrete products, or manufactured erosion-control products. Concrete-lined swales are the only type of lining covered in this practice.
Digging a swale is an ideal way to direct excess water when it causes erosion on a hill or slope. A swale should slope downhill, and the trench should gradually get deeper. If your landscape allows, the swale should deepen by one inch for every 10 feet. It should also be two to three times as wide as it is deep.