Stormwater Management & Best Management Practices

Specific Types of Best Management Practices

Structural BMPs

Structural Stormwater Best Management Practices (BMPs) are engineered systems that are designed to mitigate the impacts of stormwater. Structural BMPs are effective tools for stormwater management in both development and retrofit situations.  Structural BMPs include systems that rely on the natural processes of soil and vegetation (e.g. Vegetated Swale) as well as systems that rely on manufactured components (e.g. Water Quality Filters). Structural BMPs can be utilized to reduce volume and peak flows, and improve water quality. 

Read below to learn about specific types of Structural BMPs.  Additional information can be found at:

Infiltration Basins and Trenches
Infiltration devices drain or infiltrate water directly into the ground, providing opportunity for groundwater recharge.  Infiltration facilities are below ground; the length of time that water is allowed to be on the surface is determined by municipal codes.

Dry Wells
Dry wells collect and infiltrate roof runoff at gutter downspouts, roof valleys, and other places where large amounts of concentrated water flow off of a roof. The water is conveyed typically through a underground pipe into a They help reduce erosion on your property and can reduce ponding and sitting water. Read more at the links below:

Rain Barrells
Rain Barrels at Phipps Conservatory, Allegheny County

Rain Barrels
A rain barrel is a device to collect rainwater from downspouts.  Rain barrels can be purchased or can be made at home.  They come in all sizes and shapes.  Some benefits of rain barrels include: reduction of stormwater runoff, promotion of local watershed awareness, education of neighbors about stormwater issues, lowered water bill by reducing metered water usage, and water reuse for landscaping, washing, etc. 

For more information on rain barrels, please see the following links:

Rain Gardens
A rain garden is a landscaped area planted with wild flowers and other native vegetation that is used to soak up rain water, from the roof, driveway, and lawn. The water slowly seeps into the ground instead of heading for the nearest storm drain. A rain garden allows for significantly more water to soak into the ground than a conventional lawn.

For more information on rain gardens please see the following links:

Rain Barrells
Pervious Concrete Pavers at Phipps Conservatory, Allegheny County

Pervious Pavement
Porous asphalt, porous concrete, and porous pavers are all types of pervious pavements.  These are typically used with infiltration beds below the pervious surfaces which allow for the temporary stormwater storage and infiltration into the ground.  These technologies are used for stormwater peak rate control.  Learn more below.

Subsurface Infiltration Bed
Temporary storage and infiltration can be attained when including subsurface infiltration beds underneath vegetated surfaces.  Subsurface infiltration beds are typically filled with stones (for void space) and wrapped in geotextile fabric.  Subsurface infiltration beds work well in large and generally flat spaces that are located downhill from impervious areas.  Learn more below.

Vegetated Swale
Vegetated swales, also known as bioswales, are broad channels that are densely planted with vegetation.  Designed to attenuate and sometimes infiltrate flow, vegetated swales provide peak rate control and also allow for pollutants to settle out, therefore improving water quality.  In sloped areas, check dams are needed to enhance the stormwater management functions of vegetated swales.  Learn more below.

Vegetated Filter Strip
Vegetated Filter Strips, also called Buffer Strips, are areas in between sources of non-point source pollutants and the receiving body of water.  They can include native or indigenous vegetation such as grasses, shrubs, and trees.  Turf grasses are also used sometimes but their functionality in stormwater management is limited.  The primary stormwater function of vegetated filter strips is water quality improvement, however, some volume reduction and ground water recharge can occur depending on site conditions such as soil and slope.  Learn more below. 

Constructed Filter
A constructed stormwater filter is a structure or excavated area that is filled with material that filters stormwater.  These devices can be designed to filter floatables, sediments, metals, hydrocarbons, and other pollutants.  There are many variations on the constructed filter, including vegetated and non-vegetated, infiltration, contained, subsurface, and linear perimeter filters.  Learn more below.

Infiltration Berm & Retentive Grading
Infiltration berms are linear landscape features that are parallel to existing site contours in areas with moderate slops.  They are earthen embankments that divert, retain, slow down, divert, and promote the infiltration of stormwater.  Berms are most effective in areas that receive runoff from small impervious areas.  Retentive grading creates small depressions that store and infiltrate stormwater.  Learn more below.

Vegetated Roof
Vegetated Roofs are roofs that are covered with specialized media and planted with vegetation; this enables the roof to hydrologically perform in a manner similar to vegetated surfaces. The media holds water which is eventually evapotranspired by the plants. Vegetated roofs’ primary function in stormwater management is volume reduction. Additional stormwater benefits include water quality improvements and some peak rate control. Environmental benefits beyond stormwater control include building temperature moderation and wildlife habitat.  Learn more below.

Runoff Capture & Reuse
Runoff Capture and Reuse refers to the variety of techniques that are used to capture precipitation, store it for period of time, and reuse the water.  Devices used to capture and store stormwater include rain barrels, cisterns, vertical storage mechanisms, and below-ground storage systems. These BMPs are most effective for use in controlling small, frequent storm events.  Stormwater management benefits of runoff capture and reuse devices include volume reduction, water quality improvements, peak rate control, and groundwater recharge.  Learn more below.

Constructed Wetland
Constructed Wetlands (CWs), also known as stormwater wetlands, are shallow aquatic systems planted with emergent vegetation.  They are highly effective at removing pollutants from stormwater; they also mitigate peak flow rates and reduce runoff volume. Beyond stormwater management, CWs provide wildlife habitat and aesthetic value.   Detention Basins, a basic BMP that temporarily stores stormwater, are often retrofitted into CWs in order to maximize stormwater management function of the space and obtain the added benefits. Learn more below.

Wet Pond/Retention Basin
Wet Ponds (WPs), also called Retention Basins, are stormwater basins that include a permanent pool of water as well as additional capacity for the temporary storage of stormwater.   They are very effective at controlling peak stormwater rates and also provide water quality benefits.  Beyond stormwater management, WPs can also provide aesthetic and wildlife benefits.  Learn more below.

Dry Extended Detention Basin
Dry Extended Detention Basins (DEDBs) are detention basins which are designed to provide temporary stormwater storage and water quality benefits.  The temporary storage of stormwater prevents downstream flooding.  Water quality benefits are achieved through sediment settling out of the stormwater while held in the DEDB.  DEDBs are often used in conjunction with other BMPs to maximize stormwater management benefits on site.    The DEDB is a design enhancement from the Dry Detention Basin, which has been popular since the 1970s.  The extended detention of stormwater maximizes water quality benefits.  Learn more below.

Water Quality Filters & Hydrodynamic Devices
Water Quality Filters are stormwater inlets that are fitted with devices to filter pollutants from stormwater.  Hydrodynamic devices are separate from inlets, but serve the same function of filtering pollutants.  Both Water Quality Filters and Hydrodynamic Devices rely on some form of settling and filtration to remove pollutants from runoff.  There are numerous variations available commerically.  Learn more below. 

Riparian Buffer Restoration
Riparian Buffer Restoration (RBR) is the restoration of the area surrounding streams, lakes, ponds, and wetlands.  The restoration of these areas provides numerous stormwater management benefits, including water quality improvement, volume reduction, groundwater recharge, and peak rate control.  Ecological benefits beyond stormwater management are numerous, including providing wildlife habitat and providing aesthetic value.  Learn more below.

Landscape Restoration
Landscape Restoration is the term used for the implementation of sustainable landscape practices outside of the Riparian Buffer and/or other specially protected areas.  Landscape Restoration can include forest restoration, meadow restoration, and the conversion of turf to meadow.  Native plants should be used and the use of pesticides and herbicides should be eliminated if possible.  Learn more below.          

Soil Amendment & Restoration
The Soil Amendment & Restoration BMP refers to the process of improving disturbed soils. By reducing compaction and adding organic materials, stormwater infiltration and pollutant removal capacity can be greatly increased.  In addition to the added stormwater capacity of the soil itself, soil amendment and restoration improves conditions for growing vegetation, which further improves stormwater management.  Learn more below. 

Floodplain Restoration
Floodplain Restoration aims to restore a floodplain to conditions present prior to development (pre-1600s).  It is a system-based BMP that strives to mimic undisturbed conditions between groundwater, stream baseflow, and vegetation. Floodplain Restoration provides substantial water quality and quantity stormwater management benefits.  Learn more below:

Level Spreader
Level spreaders are a structural BMP that is designed to reduce the erosive energy of stormwater.  Examples of Level Spreaders include earthen berms, level perforated pipes, or concrete curbs.  Level spreaders are often used in conjunction with other BMPs such as Filter Strips; Filter Strips function significantly better when stormwater is distributed across the BMP.   Learn more below:

Special Detention Areas
The implementation of Special Detention Areas entails using spaces that are not typically utilized for stormwater management, such as parking lots, to temporarily detain stormwater.  A flow control structure is typically used to allow runoff to pond.  This BMP is specifically used to control peak rate volume and is more effective when combined with other BMPs that address water quality and volume reduction.  Learn more below: 

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