Vegetated Swales
These are primarily designed to convey stormwater runoff in a longitudinal manner through a
drainage pathway. Their main function is to transport water from one point to another while
promoting infiltration, pollutant removal, and erosion control.
Water Treatment: While they may provide some level of water quality improvement by reducing
flow velocities and filtering out sediments, vegetated swales primarily focus on conveyance
rather than treatment.
Design and Construction: The design of vegetated swales emphasizes efficient conveyance
of stormwater, with considerations for slope, vegetation types, and erosion control measures.
They are typically simpler in design compared to bioretention swales.
Infiltration vs Conveyance: While infiltration may occur to some extent, the primary function is
to convey stormwater from one point to another. Infiltration is not the main focus.
Bioretention Swales:
These are designed not only to convey stormwater but also to capture, treat, and infiltrate
runoff. They typically contain engineered soil mixes and vegetation specifically chosen to
enhance pollutant removal and water infiltration
Water Treatment: These are specifically designed to improve water quality by capturing and
filtering pollutants as runoff passes through the engineered soil media and plant root systems.
They are effective in removing sediment, nutrients, heavy metals, and other contaminants from
stormwater.
Design and Construction: These require more specialized design and construction techniques
to ensure proper infiltration, pollutant removal, and maintenance. They incorporate layers of
engineered soil media, underdrains for excess water management, and specific plant selections
to optimize water treatment capabilities.
Infiltration vs Conveyance: These are designed to maximize infiltration of stormwater into the
soil, promoting groundwater recharge and reducing the volume of runoff discharged into
conventional drainage systems.
In summary, vegetated swales primarily focus on conveyance of stormwater, whereas bioretention
swales are specifically designed for water treatment, pollutant removal, and infiltration.
Bioretention swales are more complex in design and construction, with a greater emphasis on
improving water quality.
Bioretention Basin (Rain Garden) - is a landscaped depression or shallow basin designed to
capture, treat, and infiltrate stormwater runoff. It is a type of green infrastructure that mimics
natural hydrological processes to manage urban stormwater runoff in a sustainable way.
Design: Bioretention basins are typically designed with gentle slopes and vegetated areas that
allow stormwater to flow into the basin. The design aims to mimic natural processes by
incorporating elements such as soil, plants, and mulch to treat and infiltrate runoff.
Soil Media: The basin is filled with a specially engineered soil mix that promotes water
infiltration and provides a medium for pollutant removal. This soil mix is designed to retain water
while allowing it to slowly percolate into the ground.
Vegetation: A variety of native or adapted plants are selected for the basin based on their ability
to tolerate periodic flooding, filter pollutants, and enhance biodiversity. These plants help to
stabilize the soil, take up excess nutrients, and provide habitat for wildlife.
Underdrains: In some cases, bioretention basins may include underdrains to manage excess
water during heavy rainfall events. These underdrains help to prevent flooding and ensure that
the basin functions effectively even during extreme weather.
Overflow Management: Bioretention basins are designed with overflow structures or features
to safely convey excess water when the basin reaches its capacity. This prevents flooding and
ensures that stormwater is managed effectively.
Maintenance: Regular maintenance is essential to keep the bioretention basin functioning
properly. This may include removing debris, controlling weeds, replenishing mulch, and
inspecting the drainage system.
Bioretention basins provide numerous benefits beyond stormwater management, including
improving water quality, reducing erosion, enhancing wildlife habitat, and adding aesthetic value
to the landscape. They are increasingly being incorporated into urban and suburban
environments as part of sustainable stormwater management practices.
Sediment Basin – is a purpose-built dam designed to collect and settle sediment-laden water. It
usually consists of an inlet chamber (forebay) a primary setting pond, a decent system, and a
high-flow emergency spillway. Can be located throughout the farm. Small basins can be used
within drainage lines, while larger basins should be used where water flows converge and prior
to water entering other treatment systems or natural wetlands or waterways. Site assessment
will determine whether it is better to use a series of smaller basins or a single, larger basin.
Constructed Wetland - is an artificial wetland to treat sewage, greywater, stormwater runoff
or industrial wastewater. It may also be designed for land reclamation after mining, or as
a mitigation step for natural areas lost to land development. Constructed wetlands are engineered
systems that use the natural functions of vegetation, soil, and organisms to provide secondary
treatment to wastewater. The design of the constructed wetland has to be adjusted according to the
type of wastewater to be treated. Constructed wetlands have been used in both centralized
and decentralized wastewater systems.
