As the runoff flows along the length of the swale, the vegetation slows and filters it and allows it to infiltrate into the ground. This root complex is also very efficient at moving water down into the soil and minimizing offsite flow. This mix combines both deep rooted plants and very dense fibrously rooting plants so that both the soil surface and deeper soils are protected from erosion. A bioswale or vegetated swale is a form of bioretention used to partially treat water quality, attenuate flooding potential and convey stormwater away from critical infrastructure. Site layout in the site layout, identify vegetated swale location in relation to and in consideration of buildings, water supply wells, karst, lot boundaries, site topography, drainage patterns, and existing or proposed public. I set up another control subcatchment with the same characteristics as the first as. Therefore, swales are best suited for residential, industrial, and commercial areas with low flow and smaller. Flow passes through the channel where it is filtered through the soil bed and vegetation. How to maintain your rain garden, bioswale, and micro. It is open source public software and is free for use worldwide.
The maintenance objectives for vegetated swale systems include keeping up the hydraulic and removal efficiency of the channel and maintaining. Pdf the performance of vegetated swales for urban stormwater. Portland bes vegetated swales are broad, shallow channels designed to convey and infiltrate stormwater runoff. Grass swales are vegetated open channels that are designed to manage the runoff by reducing the. Site topography may also dictate a need for additional structural controls. From a landscaping perspective, swales are barely noticeable because they are both wide and shallow. The plans included in your package provide more details. Frequency depends on location and desired aesthetic appeal. Subject to high flows, they rely on shallow slopes.
Vegetated swale inspection checklist fairfax county. From a water quality perspective, they are preferable to pipes because they allow more soil and water contact, as well as more opportunity for infiltration. The minimum drainage area contributing to a vegetated swale is not restricted. The first step in designing a vegetated swale is to determine the constraints of the site. Draft for public comment wisconsin department of natural. These systems are linear, with length to width dimensions much greater than the more typical 2. As with any stormwater management structure, property owners should provide a budget for ongoing maintenance, such as regular mowing and repairs as. Vegetated swales serve to remove sediment, nutrients and other contaminants, increase infiltration, and beautify the development.
A vegetated swale is a gently sloping landscaped depression that. Vegetated swale tc30 january 2003 california stormwater bmp handbook 5 of new development and redevelopment. It is designed to attenuate and in ut in the process. Average annual operating and maintenance costs of vegetated swales can be estimated using table 3. Vegetated swales can serve as part of a stormwater drainage system and can replace curbs, gutters and storm sewer systems. These open, shallow channels slow runoff, filter it, and promote infiltration into the ground. The useful life of a vegetated swale system is directly proportional to its maintenance frequency. Green solution vegetated swale 3 rivers wet weather. Parallel swales may be used if calculations show greater width is needed. A vegetated swale typically contains the following components. There are many urban stormwater management softwares available in.
As the property owner, you are responsible for all of the maintenance. A sediment has filled entire basin and is level with the drop inlet b presence of cattails indicate wetland conditions and failure to drain properly c use of nonselective herbicide led to swale erosion regulated municipal separate storm sewer systems ms4s are required to address maintenance as. Vegetated swales in urban stormwater modeling and management kyle w. These facilities need regular maintenance, similar to other landscaped areas, including. Waters design features 2018 edition on vegetated swales, bioretention. Volume 2 technical handbook georgia stormwater management manual 4. A new software to estimate vehicle emissions in australia. The vegetated swale should be inspected at least two times a year, once in the spring and once in the fall, by a qualiied representative of the owner or qualiied owner familiar with the design and maintenance requirements of the vegetated swale.
In germany, the construction and maintenance of infiltration swales is. A drainage swale, also known as a vegetated swale or grass swale, is just a fancy term for a wide shallow ditch that is designed to carry away runoff water from rain, sprinklers, and so on. Vegetated swale official website for the city of sandy. Grass swales wv department of environmental protection. Vegetated swales typically cost less to construct than curbs and gutters or underground stormwater conveyance pipes. As runoff passes through the vegetation, contaminants are removed by. The decisions made by everyone on the project team play a role in how costly or easy is will be to maintain gi practices. How to maintain your drainage swale page 1 of 2 20 l montgomery county, maryland. You can prolong the life of your swale and save on maintenance. For example, vegetated filtration systems display lower cost and invested personnel hours than conventional pond systems. Total suspended solids tss sediment oil and grease organics metals background vegetated swales are shallow, open.
Pdf vegetated swales are becoming a common feature of water. A vegetated swale is a broad, shallow, trapezoidal or parabolic channel, densely planted with a variety of trees, shrubs, andor grasses. Designers may choose to utilize available hydraulic design software to. Wet swales are designed to retain water and maintain marshy conditions for the support of aquatic vegetation. The densely planted swale filters stormwater as it flows the length of the swale and allows infiltration of water into the ground. Check for sediment accumulation and erosion within the swale. The design of swales seeks to reduce stormwater volume. I set up a vegetative swale lid control that occupies the full subcatchment. Palm coast has an effective drainage system that is.
The swales are vegetated along the bottom and sides of the channel, with side vegetation at a height greater than the maximum design stormwater volume. The topography of the site should permit the design of a channel with appropriate slope and crosssectional area. In steeper slope situations, check dams a vegetated swale is a broad, shallow, trapezoidal or some cases infiltrate runoff volume from adjacent. The enhanced grassed swale is a vegetated open conveyance channel designed to include a filter bed of prepared soil that overlays an underdrain system. Vegetated swales are particularly well suited to small drainage areas. The goal is to sustain the citys original swale design so that it functions in the way it was built to perform. Vegetated swale parabolic channel, densely planted with a variety of trees, shrubs, andor grasses. These low maintenance plant communities may be established wherever runoff must be transported from hardscapes to retention areas. Vegetated swales bioswales, grassy swales s wales are gently sloping depressions planted with dense vegetation or grass that treat stormwater runoff from rooftops, streets, and parking lots. If properly designed and regularly maintained, vegetated swales can last indefinitely. It is designed to attenuate and in some cases infiltrate runoff volume from adjacent impervious surfaces, allowing some pollutants to settle out in the process. They are vegetated, open channels, most often lined with grass.
Table 2 shows the estimated capital costs of a vegetated swale. Vegetated swales are an excellent alternative to conventional curb and gutter conveyance. Pdf urban stormwater management model and tools for. Chapter 9 swale and filter strip design, construction and maintenance 9. A vegetated swale, also called a drainage swale or bioswale, is a shallow stormwater channel that is densely planted with a variety of grasses, shrubs, andor trees designed to slow, filter, and infiltrate stormwater runoff. Storm water management model swmm water research us epa. The water quality improvement function of a vegetated swale is predicated on its ability to maintain minimal flow velocities within the channel. Open channels that use vegetation to primarily remove suspended solids. Vegetated open channels that are designed to convey the design storm volume rpv and cv, may also convey the fv as designed. The bed of the swale flow area shall slope at about 2% from toe of side slope to center of swale. Vegetated swales shall have a maximum treatment width of 10 feet. Vegetated swales are an important low impact development technique used to convey stormwater runoff. Vegetated swales can serve as conveyance for storm water in place of traditional curbs and gutters.
Epas storm water management model swmm is used throughout the world for planning, analysis, and design related to stormwater. Wsud treatment measures design and maintenance considerations. Runoff is collected and conveyed by a perforated pipe and gravel underdrain system to the outlet. White abstract despite the runoff reduction efficiencies recommended by various regulatory agencies, minimal research exists regarding the ability of vegetated swales to. The vegetated swale bed shall be at least 2feet wide and no more than 7 feet wide. Grass vegetated channels systems shall n ot be designed to provide storm water detention.