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<!--[[File:Pdf image.png|100px|thumb|alt=pdf image|<font size=3>[ Download pdf]</font size>]]-->
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[[File:Pdf image.png|100px|thumb|alt=pdf image|<font size=3>[https://stormwater.pca.state.mn.us/index.php?title=File:Green_Infrastructure_benefits_of_infiltration_practices_-_Minnesota_Stormwater_Manual.pdf Download pdf]</font size>]]
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[[File:picture of permeable interlocking concrete pavement 1.jpg|thumb|300 px|alt=Photo illustrating permeable interlocking pavement. Permeable interlocking pavers consist of concrete or stone units with open, permeable spaces between the units.|<font size=3>Photo illustrating permeable interlocking concrete pavement.</font size>]]
 
[[File:picture of permeable interlocking concrete pavement 1.jpg|thumb|300 px|alt=Photo illustrating permeable interlocking pavement. Permeable interlocking pavers consist of concrete or stone units with open, permeable spaces between the units.|<font size=3>Photo illustrating permeable interlocking concrete pavement.</font size>]]
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[[file:RG pic1.jpg|thumb|300px|alt=photo of a rain garden|<font size=3>Bioinfiltration (rain garden) in a residential development. Photo courtesy of Katherine Sullivan.</font size>]]
 
[[file:RG pic1.jpg|thumb|300px|alt=photo of a rain garden|<font size=3>Bioinfiltration (rain garden) in a residential development. Photo courtesy of Katherine Sullivan.</font size>]]
  
Infiltration is the practice of draining water into soils, typically through engineered systems such as <span title="Bioretention, also called rain gardens, is a terrestrial-based (up-land as opposed to wetland) water quality and water quantity control process. Bioretention employs a simplistic, site-integrated design that provides opportunity for runoff infiltration, filtration, storage, and water uptake by vegetation. Bioretention areas are suitable stormwater treatment practices for all land uses, as long as the contributing drainage area is appropriate for the size of the facility. Common bioretention opportunities include landscaping islands, cul-de-sacs, parking lot margins, commercial setbacks, open space, rooftop drainage and street-scapes (i.e., between the curb and sidewalk). Bioretention, when designed with an underdrain and liner, is also a good design option for treating Potential stormwater hotspots. Bioretention is extremely versatile because of its ability to be incorporated into landscaped areas. The versatility of the practice also allows for bioretention areas to be frequently employed as stormwater retrofits."> '''bioinfiltration'''</span> (rain gardens), <span title="Infiltration basins, infiltration trenches, dry wells, and underground infiltration systems capture and temporarily store stormwater before allowing it to infiltrate into the soil. As the stormwater penetrates the underlying soil, chemical, biological and physical processes remove pollutants and delay peak stormwater flows."> [https://stormwater.pca.state.mn.us/index.php?title=Infiltration '''infiltration basins''']</span>, <span title="Dry swales, sometimes called grass swales, are similar to bioretention cells but are configured as shallow, linear channels. They typically have vegetative cover such as turf or native perennial grasses. Dry swales may be constructed as filtration or infiltration practices, depending on soils."> [https://stormwater.pca.state.mn.us/index.php?title=Dry_swale_(Grass_swale) '''dry swales''']</span> with <span title="A check dam is a structure installed perpendicular to flow in a natural or manmade conveyance channel to reduce flow velocity. By slowing flow velocities, check dams can serve multiple functions including reduction of channel scour and erosion, enhancement of sediment trapping, and greater treatment of the water quality control volume via enhanced water detention or retention. Typical check dam materials include rock, earth, wood, and concrete. "> '''check dams'''</span>, and <span title="Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir for temporary storage and/or infiltration. The most commonly used permeable pavement surfaces are pervious concrete, porous asphalt, and permeable interlocking concrete pavers (PICP)."> '''[https://stormwater.pca.state.mn.us/index.php?title=Permeable_pavement permeable pavement]'''</span>. The practice of infiltration is beneficial for soils, maintaining natural hydrology, and has a significant water quality impact for downstream lakes, rivers, and ponds. Depending on design, stormwater infiltration practices can be a key component of GI to promote the health and well-being of animals, vegetation, and the people that rely upon these waters when designing sites.
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Infiltration is the practice of draining water into soils, typically through engineered systems such as <span title="Bioretention, also called rain gardens, is a terrestrial-based (up-land as opposed to wetland) water quality and water quantity control process. Bioretention employs a simplistic, site-integrated design that provides opportunity for runoff infiltration, filtration, storage, and water uptake by vegetation. Bioretention areas are suitable stormwater treatment practices for all land uses, as long as the contributing drainage area is appropriate for the size of the facility. Common bioretention opportunities include landscaping islands, cul-de-sacs, parking lot margins, commercial setbacks, open space, rooftop drainage and street-scapes (i.e., between the curb and sidewalk). Bioretention, when designed with an underdrain and liner, is also a good design option for treating Potential stormwater hotspots. Bioretention is extremely versatile because of its ability to be incorporated into landscaped areas. The versatility of the practice also allows for bioretention areas to be frequently employed as stormwater retrofits."> '''bioinfiltration'''</span> (rain gardens), <span title="Infiltration basins, infiltration trenches, dry wells, and underground infiltration systems capture and temporarily store stormwater before allowing it to infiltrate into the soil. As the stormwater penetrates the underlying soil, chemical, biological and physical processes remove pollutants and delay peak stormwater flows."> [https://stormwater.pca.state.mn.us/index.php?title=Infiltration '''infiltration basins''']</span>, <span title="Dry swales, sometimes called grass swales, are similar to bioretention cells but are configured as shallow, linear channels. They typically have vegetative cover such as turf or native perennial grasses. Dry swales may be constructed as filtration or infiltration practices, depending on soils."> [https://stormwater.pca.state.mn.us/index.php?title=Dry_swale_(Grass_swale) '''dry swales''']</span> with <span title="A check dam is a structure installed perpendicular to flow in a natural or manmade conveyance channel to reduce flow velocity. By slowing flow velocities, check dams can serve multiple functions including reduction of channel scour and erosion, enhancement of sediment trapping, and greater treatment of the water quality control volume via enhanced water detention or retention. Typical check dam materials include rock, earth, wood, and concrete. "> '''check dams'''</span>, and <span title="Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir for temporary storage and/or infiltration. The most commonly used permeable pavement surfaces are pervious concrete, porous asphalt, and permeable interlocking concrete pavers (PICP)."> '''[https://stormwater.pca.state.mn.us/index.php?title=Permeable_pavement permeable pavement]'''</span>. The practice of infiltration is beneficial for soils, maintaining natural hydrology, and has a significant water quality impact for downstream lakes, rivers, and ponds. Depending on design, stormwater infiltration practices can be a key component of <span title="Green Infrastructure refers to ecological systems, both natural and engineered, that act as living infrastructure. Green Infrastructure elements are planned and managed primarily for stormwater control, but also exhibit social, economic and environmental benefits (Syracuse University)."> '''green infrastructure'''</span> (GI) to promote the health and well-being of animals, vegetation, and the people that rely upon these waters when designing sites.
  
 
Some of the more common infiltration practices include
 
Some of the more common infiltration practices include
*infiltration basins and trenches,
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*[[Permeable pavement]]
*rain gardens,
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*[[Trees|Tree trench/tree box]]
*vegetated swales,
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*[[Bioretention|Bioretention - bioinfiltration]]
*underground infiltration systems,
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**Note: '''Bioretention practices are often called Rain Gardens'''
*permeable pavement, and
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*[[Infiltration]] - this links to the following practices
*tree trenches.
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**Infiltration trench, including dry wells
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**Infiltration basin
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**Underground infiltration
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*[[Dry swale (Grass swale)]]
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*[[High-gradient stormwater step-pool swale]]
  
 
For further reading on different types of infiltration, see [[Stormwater infiltration Best Management Practices]] and [[BMPs for stormwater infiltration]].
 
For further reading on different types of infiltration, see [[Stormwater infiltration Best Management Practices]] and [[BMPs for stormwater infiltration]].
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{{alert|On sites where the Construction Stormwater General Permit applies, infiltration may be prohibited due to site conditions. For more information, see [[When infiltration is not authorized under a stormwater permit]]|alert-danger}}
  
 
==Green infrastructure and multiple benefits==
 
==Green infrastructure and multiple benefits==
 
<span title="Green stormwater infrastructure is designed to mimic nature and capture rainwater where it falls. Green infrastructure reduces and treats stormwater at its source while while also providing multiple community benefits such as improvements in water quality, reduced flooding, habitat, carbon capture, etc."> '''Green infrastructure'''</span> (GI) encompasses a wide array of practices, including stormwater management. <span title="Green stormwater infrastructure (GSI) describes practices that use natural systems (or engineered systems that mimic or use natural processes) to capture, clean, and infiltrate stormwater; shade and cool surfaces and buildings; reduce flooding, create wildlife habitat; and provide other services that improve environmental quality and communities’ quality of life. (City of Tucson)"> '''Green stormwater infrastructure'''</span> (GSI) encompasses a variety of practices primarily designed for managing stormwater runoff but that provide additional benefits such as habitat or aesthetic value.
 
<span title="Green stormwater infrastructure is designed to mimic nature and capture rainwater where it falls. Green infrastructure reduces and treats stormwater at its source while while also providing multiple community benefits such as improvements in water quality, reduced flooding, habitat, carbon capture, etc."> '''Green infrastructure'''</span> (GI) encompasses a wide array of practices, including stormwater management. <span title="Green stormwater infrastructure (GSI) describes practices that use natural systems (or engineered systems that mimic or use natural processes) to capture, clean, and infiltrate stormwater; shade and cool surfaces and buildings; reduce flooding, create wildlife habitat; and provide other services that improve environmental quality and communities’ quality of life. (City of Tucson)"> '''Green stormwater infrastructure'''</span> (GSI) encompasses a variety of practices primarily designed for managing stormwater runoff but that provide additional benefits such as habitat or aesthetic value.
  
There is no universal definition of GI or GSI ([https://www.interreg-central.eu/Content.Node/Definitions.html link here fore more information]). Consequently, the terms are often interchanged, leading to confusion and misinterpretation. GSI practices are designed to function as stormwater practices first (e.g. flood control, treatment of runoff, volume control), but they can provide additional benefits. Though designed for stormwater function, GSI practices, where appropriate, should be designed to deliver multiple benefits (often termed "multiple stacked benefits". For more information on green infrastructure, ecosystem services, and sustainability, link to [[Multiple benefits of green infrastructure and role of green infrastructure in sustainability and ecosystem services]].
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There is no universal definition of GI or GSI ([https://www.interreg-central.eu/Content.Node/Definitions.html link here for more information]). Consequently, the terms are often interchanged, leading to confusion and misinterpretation. GSI practices are designed to function as stormwater practices first (e.g. flood control, treatment of runoff, volume control), but they can provide additional benefits. Though designed for stormwater function, GSI practices, where appropriate, should be designed to deliver multiple benefits (often termed "multiple stacked benefits". For more information on green infrastructure, ecosystem services, and sustainability, link to [[Multiple benefits of green infrastructure and role of green infrastructure in sustainability and ecosystem services]].
  
 
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==Green Infrastructure benefits of infiltration practices==
 
==Green Infrastructure benefits of infiltration practices==
*[https://stormwater.pca.state.mn.us/index.php?title=Water_quality_benefits_of_Green_Stormwater_Infrastructure '''Water quality''']: Stormwater infiltration practices are excellent water quality treatment practices. Engineered media, soils, and the underlying vadose zone provide effective retention of most pollutants, as indicated in the accompanying table. Chloride and nitrate are exceptions, though concentrations of these are generally below water quality standards except for chloride during deicing season. Infiltration should be avoided in areas where contaminants in soil or groundwater may be mobilized by infiltrating water. For more information, see [[Surface water and groundwater quality impacts from stormwater infiltration]]
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*[https://stormwater.pca.state.mn.us/index.php?title=Water_quality_benefits_of_Green_Stormwater_Infrastructure '''Water quality''']: Stormwater infiltration practices are excellent water quality treatment practices. Engineered media, soils, and the underlying vadose zone provide effective retention of most pollutants (see [[Minimum bioretention soil media depths recommended to target specific stormwater pollutants]]). Chloride and nitrate are exceptions, though concentrations of these are generally below <span title="Water quality standards (WQS) are provisions of state, territorial, authorized tribal or federal law approved by EPA that describe the desired condition of a water body and the means by which that condition will be protected or achieved."> '''water quality standards'''</span> except for chloride during <span title="Deicing typically refers to removal of salt from impervious surfaces, such as roads, driveways, parking lots, and sidewalks. Chemicals, most commonly sodium chloride, are often used for deicing."> '''deicing'''</span> season. Infiltration should be avoided in areas where contaminants in soil or groundwater may be mobilized by infiltrating water. For more information, see [[Surface water and groundwater quality impacts from stormwater infiltration]]
 
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*[https://stormwater.pca.state.mn.us/index.php?title=Water_quantity_and_hydrology_benefits_of_Green_Stormwater_Infrastructure '''Water quantity and hydrology''']: Infiltration practices reduce the volume of stormwater runoff and retard peak flow from rainfall events, thus reducing flood potential in areas downstream of the practice. They are most effective for small- and medium-intensity rain and runoff events unless sized to meet larger events. Infiltration promotes groundwater recharge, potentially increasing <span title="Baseflow (also called drought flow, groundwater recession flow, low flow, low-water flow, low-water discharge and sustained or fair-weather runoff) is the portion of streamflow delayed shallow subsurface flow".> '''baseflow'''</span> and/or recharge of deeper aquifers.
{{:Minimum bioretention soil media depths recommended to target specific stormwater pollutants
 
}}
 
 
 
*[https://stormwater.pca.state.mn.us/index.php?title=Water_quantity_and_hydrology_benefits_of_Green_Stormwater_Infrastructure '''Water quantity and hydrology''']:Infiltration practices reduce the volume of stormwater runoff and retard peak flow from rainfall events, thus reducing flood potential in areas downstream of the practice. They are most effective for small- and medium-intensity rain and runoff events unless sized to meet larger events. Infiltration promotes groundwater recharge, potentially increasing baseflow and/or recharge of deeper aquifers.
 
 
*'''Energy savings''': Larger infiltration practices that incorporate trees and provide shade reduce air conditioning costs. Since infiltration reduces stormwater runoff, they help prevent road deterioration and reduce maintenance costs ([https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands;US EPA]).
 
*'''Energy savings''': Larger infiltration practices that incorporate trees and provide shade reduce air conditioning costs. Since infiltration reduces stormwater runoff, they help prevent road deterioration and reduce maintenance costs ([https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands;US EPA]).
 
*[https://stormwater.pca.state.mn.us/index.php?title=Air_quality_benefits_of_Green_Stormwater_Infrastructure '''Air quality''']: Benefits of infiltration practices are largely indirect, such as sequestration of carbon and other greenhouse gasses. Carbon sequestration is generally insignificant unless vegetation is incorporated into the practice and the soil or <span title="Engineered media is a mixture of sand, fines (silt, clay), organic matter, and occasionally other amendments (e.g. iron) utilized in stormwater practices, most frequently in bioretention practices. The media is typically designed to have a rapid infiltration rate, attenuate pollutants, and allow for plant growth."> [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Materials_specifications_-_filter_media '''engineered media''']</span> promotes biologic activity.
 
*[https://stormwater.pca.state.mn.us/index.php?title=Air_quality_benefits_of_Green_Stormwater_Infrastructure '''Air quality''']: Benefits of infiltration practices are largely indirect, such as sequestration of carbon and other greenhouse gasses. Carbon sequestration is generally insignificant unless vegetation is incorporated into the practice and the soil or <span title="Engineered media is a mixture of sand, fines (silt, clay), organic matter, and occasionally other amendments (e.g. iron) utilized in stormwater practices, most frequently in bioretention practices. The media is typically designed to have a rapid infiltration rate, attenuate pollutants, and allow for plant growth."> [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Materials_specifications_-_filter_media '''engineered media''']</span> promotes biologic activity.
 
*[https://stormwater.pca.state.mn.us/index.php?title=Climate_benefits_of_Green_Stormwater_Infrastructure '''Climate resiliency''']: Properly installed infiltration practices reduce the impact of flooding during rainfall events, particularly small- and medium-sized events. Vegetated infiltration systems promote photosynthesis and carbon sequestration. Incorporation of larger plants such as trees or vegetation that provides shade reduces effects of heat islands ([https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands;US EPA]).
 
*[https://stormwater.pca.state.mn.us/index.php?title=Climate_benefits_of_Green_Stormwater_Infrastructure '''Climate resiliency''']: Properly installed infiltration practices reduce the impact of flooding during rainfall events, particularly small- and medium-sized events. Vegetated infiltration systems promote photosynthesis and carbon sequestration. Incorporation of larger plants such as trees or vegetation that provides shade reduces effects of heat islands ([https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands;US EPA]).
*[https://stormwater.pca.state.mn.us/index.php?title=Wildlife_habitat_and_biodiversity_benefits_of_Green_Stormwater_Infrastructure '''Habitat improvement''']: Infiltration results in decreased runoff and erosion, which increases soil stability. This promotes vegetation growth that further stabilizes a site and creates habitat for birds, pollinator insects, and potentially small mammals. Soil or media may be engineered to promote invertebrate avtivity. Reduced runoff associated with increased infiltration reduces adverse effects of elevated temperatures that harm coldwater organisms.
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*[https://stormwater.pca.state.mn.us/index.php?title=Wildlife_habitat_and_biodiversity_benefits_of_Green_Stormwater_Infrastructure '''Habitat improvement''']: Infiltration results in decreased runoff and erosion, which increases soil stability. This promotes vegetation growth that further stabilizes a site and creates habitat for birds, pollinator insects, and potentially small mammals. Soil or media may be engineered to promote invertebrate activity. Reduced runoff associated with increased infiltration reduces adverse effects of elevated temperatures that harm coldwater organisms.
*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Community livability''']: Infiltration that results in groundwater recharge and improved baseflow provides increased recreational opportunities helps ensure safe and healthy access to water sources. Incorporating aesthetically pleasing landscaping when planning infiltration systems may help improve mental health of the site users ([https://www.canr.msu.edu/news/what_are_the_physical_and_mental_benefits_of_gardening What are the physical and mental benefits of gardening? - Michigan State University Extension]). Large infiltration practices that incorporate trees into the design provide shade that can reduce air temperatures ([https://www.epa.gov/sites/default/files/2014-06/documents/treesandvegcompendium.pdf Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation; EPA]).
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*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Community livability''']: Infiltration that results in groundwater recharge and improved baseflow provides increased recreational opportunities and helps ensure safe and healthy access to water sources. Incorporating aesthetically pleasing landscaping when planning infiltration systems may help improve mental health of the site users ([https://www.canr.msu.edu/news/what_are_the_physical_and_mental_benefits_of_gardening What are the physical and mental benefits of gardening? - Michigan State University Extension]). Large infiltration practices that incorporate trees into the design provide shade that can reduce air temperatures ([https://www.epa.gov/sites/default/files/2014-06/documents/treesandvegcompendium.pdf Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation; EPA]).
 
*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Health benefits''']: Infiltration provides cleaner waterways through the reduction of nutrients, pathogens, metals, TSS, and phosphorus and provides healthier environments to the humans, wildlife, and vegetation that use these waters.
 
*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Health benefits''']: Infiltration provides cleaner waterways through the reduction of nutrients, pathogens, metals, TSS, and phosphorus and provides healthier environments to the humans, wildlife, and vegetation that use these waters.
 
*[https://stormwater.pca.state.mn.us/index.php?title=Economic_benefits_of_Green_Stormwater_Infrastructure '''Economic benefits and savings''']: In addition to water quality and flood control benefits ([https://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9496(2004)130:6(498) Braden and Johnston, 2004)], properly designed infiltration can prevent downstream cleanup costs. Well maintained infiltration systems combined with vegetation may increase property aesthetics and property value. Properly designed and functioning infiltration systems reduce downstream infrastructure costs ([https://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9496(2004)130:6(498) Braden and Johnston, 2004)].
 
*[https://stormwater.pca.state.mn.us/index.php?title=Economic_benefits_of_Green_Stormwater_Infrastructure '''Economic benefits and savings''']: In addition to water quality and flood control benefits ([https://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9496(2004)130:6(498) Braden and Johnston, 2004)], properly designed infiltration can prevent downstream cleanup costs. Well maintained infiltration systems combined with vegetation may increase property aesthetics and property value. Properly designed and functioning infiltration systems reduce downstream infrastructure costs ([https://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9496(2004)130:6(498) Braden and Johnston, 2004)].
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{{alert|The following discussion focuses on design considerations. All benefits delivered by the practice require appropriate construction, operation, and maintenance of the practice. O&M considerations should be included during the design phase of a project. For information on O&M for GSI practices, see [[Operation and maintenance of green stormwater infrastructure best management practices]]|alert-warning}}
 
{{alert|The following discussion focuses on design considerations. All benefits delivered by the practice require appropriate construction, operation, and maintenance of the practice. O&M considerations should be included during the design phase of a project. For information on O&M for GSI practices, see [[Operation and maintenance of green stormwater infrastructure best management practices]]|alert-warning}}
  
Note: Under the Minnesota Construction Stormwater Permit GI, particularly infiltration, must be considered first when selecting stormwater treatment methods.  However, if Class D soils are present on the site infiltration practices cannot be used. Class A soils are the most desirable for infiltration but infiltration systems can also be successful with B or C soils. --- Maybe add a chart indicating soil penetrability of different HSG groups —
 
 
*Water quality
 
*Water quality
**Follow [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_infiltration appropriate design guidance] to maximize capture of runoff. Consider local climate characteristics ([https://indigo.uic.edu/articles/journal_contribution/The_Environmental_and_Ecological_Benefits_of_Green_Infrastructure_for_Stormwater_Runoff_in_Urban_Areas/10770875 Gonzalez-Meler et al., 2013]).
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**Follow [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_infiltration appropriate design guidance] to maximize capture of runoff. Consider local climate characteristics ([https://indigo.uic.edu/articles/journal_contribution/The_Environmental_and_Ecological_Benefits_of_Green_Infrastructure_for_Stormwater_Runoff_in_Urban_Areas/10770875 Gonzalez-Meler et al., 2013]), which may affect the type and design characteristics of a practice.
**Design infiltration basins to minimize short-circuiting that results in water bypassing the treatment zones in the practice. Deep macropores may lead to short-circuiting but may be desirable for maximizing infiltration. If macropore development is encouraged, ensure water preferentially transported vertically receives appropriate treatment by ensuring underlying soils can effectively treat pollutants.
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**Design infiltration basins to minimize <span title="A condition that occurs when water flows along a nearly direct pathway from the inlet to the outlet of a tank or basin, often resulting in shorter contact, reaction, or settling times in comparison with the calculated or presumed detention times."> '''short-circuiting'''</span> that results in water <span title="Stormwater runoff in excess of the design flow, which is diverted around a stormwater structure"> '''bypassing'''</span> the treatment zones in the practice. Deep <span title="A pore in soil of such size that water drains from it by gravity and is not held by capillary action"> '''macropores'''</span> may lead to short-circuiting but may be desirable for maximizing infiltration volume. If macropore development is encouraged, ensure water preferentially transported vertically receives appropriate treatment by ensuring underlying soils can effectively treat pollutants.
 
**Infiltration systems with ecological diversity can help promote water quality treatment through effective uptake of pollutants (e.g. nutrients) or through breakdown of pollutants (e.g. promote microbiologic breakdown, such as by ensuring a food source (e.g. organic matter) and oxygenated environment). Diversifying the vegetation will remove a wider range of pollutants and maximize the water treatment
 
**Infiltration systems with ecological diversity can help promote water quality treatment through effective uptake of pollutants (e.g. nutrients) or through breakdown of pollutants (e.g. promote microbiologic breakdown, such as by ensuring a food source (e.g. organic matter) and oxygenated environment). Diversifying the vegetation will remove a wider range of pollutants and maximize the water treatment
 
**Ensure adequate <span title="Pretreatment reduces maintenance and prolongs the lifespan of structural stormwater BMPs by removing trash, debris, organic materials, coarse sediments, and associated pollutants prior to entering structural stormwater BMPs. Implementing pretreatment devices also improves aesthetics by capturing debris in focused or hidden areas. Pretreatment practices include settling devices, screens, and pretreatment vegetated filter strips."> [https://stormwater.pca.state.mn.us/index.php?title=Pretreatment '''pretreatment''']</span>
 
**Ensure adequate <span title="Pretreatment reduces maintenance and prolongs the lifespan of structural stormwater BMPs by removing trash, debris, organic materials, coarse sediments, and associated pollutants prior to entering structural stormwater BMPs. Implementing pretreatment devices also improves aesthetics by capturing debris in focused or hidden areas. Pretreatment practices include settling devices, screens, and pretreatment vegetated filter strips."> [https://stormwater.pca.state.mn.us/index.php?title=Pretreatment '''pretreatment''']</span>
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**Promoting macropore development results in increased infiltration. Macropores are associated with vegetation and increased invertebrate activity. These can be enhanced through use of deep-rooted perennial vegetation and organic-rich <span title="Engineered media is a mixture of sand, fines (silt, clay), organic matter, and occasionally other amendments (e.g. iron) utilized in stormwater practices, most frequently in bioretention practices. The media is typically designed to have a rapid infiltration rate, attenuate pollutants, and allow for plant growth."> [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Materials_specifications_-_filter_media '''engineered media''']</span> or soil ([https://www.sciencedirect.com/science/article/pii/S030147971530058X Ossola et. al, 2015]).
 
**Promoting macropore development results in increased infiltration. Macropores are associated with vegetation and increased invertebrate activity. These can be enhanced through use of deep-rooted perennial vegetation and organic-rich <span title="Engineered media is a mixture of sand, fines (silt, clay), organic matter, and occasionally other amendments (e.g. iron) utilized in stormwater practices, most frequently in bioretention practices. The media is typically designed to have a rapid infiltration rate, attenuate pollutants, and allow for plant growth."> [https://stormwater.pca.state.mn.us/index.php?title=Design_criteria_for_bioretention#Materials_specifications_-_filter_media '''engineered media''']</span> or soil ([https://www.sciencedirect.com/science/article/pii/S030147971530058X Ossola et. al, 2015]).
 
**Distributed infiltration systems throughout an area site typically provide increased hydrologic capacity, partly as a result of reducing the risk and impacts of system failure. One way to increase distribution of infiltration systems is to encourage infiltration on individual parcels ([https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/wrcr.20317 Cadavid and Ando, 2013]; [https://www.sciencedirect.com/science/article/abs/pii/S0043135422002366 Shahzad et al., 2022]).
 
**Distributed infiltration systems throughout an area site typically provide increased hydrologic capacity, partly as a result of reducing the risk and impacts of system failure. One way to increase distribution of infiltration systems is to encourage infiltration on individual parcels ([https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/wrcr.20317 Cadavid and Ando, 2013]; [https://www.sciencedirect.com/science/article/abs/pii/S0043135422002366 Shahzad et al., 2022]).
**Maximize water storage by [https://stormwater.pca.state.mn.us/index.php?title=Soil_water_storage_properties manipulating the media] and incorporating [http://chesapeakestormwater.net/wp-content/uploads/downloads/2014/03/Internal-Water-Storage-for-Bioretention-2009.pdf internal storage].
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**Maximize water storage by [https://stormwater.pca.state.mn.us/index.php?title=Soil_water_storage_properties manipulating the media] and incorporating [https://epa.ohio.gov/static/Portals/41/storm_workshop/lid/IWS.Dec10.pdf internal storage].
 
**Increase the size of infiltration systems, if feasible, to maximize capture of runoff.
 
**Increase the size of infiltration systems, if feasible, to maximize capture of runoff.
 
*Climate resiliency:
 
*Climate resiliency:
**To reduce heat island effects, select vegetation that reflects solar energy, absorbs solar energy and releases it slowly, or that maximizes evapotranspiration [http://www1.nyc.gov/assets/orr/images/content/header/ORR_ClimateResiliencyDesignGuidelines_PRELIMINARY_4_21_2017.pdf NYC Mayor’s Office of Recovery and Resiliency].
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**To reduce heat island effects, select vegetation that reflects solar energy, absorbs solar energy and releases it slowly, or that maximizes evapotranspiration ([https://www1.nyc.gov/assets/orr/pdf/NYC_Climate_Resiliency_Design_Guidelines_v4-0.pdf NYC Mayor’s Office of Recovery and Resiliency]).
**Oversize bowl depth (storage) to account for increased precipitation. [http://wildlife.ohiodnr.gov/portals/wildlife/PDFs/Public%20Areas/BRC%20and%20PP%20Climate%20Change%20(US%20units).pdf Winston (2016)] recommends oversizing by 33-45% for bioretention in northern Ohio. Oversizing can also be accomplished by reducing loading to individual bioretention practices.
+
**Oversize bowl depth (storage) to account for increased precipitation. [https://pubmed.ncbi.nlm.nih.gov/26906696/ Winston (2016)] recommends oversizing by 33-45% for bioretention in northern Ohio. Oversizing can also be accomplished by reducing loading to individual bioretention practices.
**Establish thicker media depths ([http://wildlife.ohiodnr.gov/portals/wildlife/PDFs/Public%20Areas/BRC%20and%20PP%20Climate%20Change%20(US%20units).pdf Winston (2016)] recommends 48 to 102 inches for northern Ohio) to enhance vegetation survival during wet or extended dry periods.
+
**Establish thicker media depths ([https://pubmed.ncbi.nlm.nih.gov/26906696/ Winston (2016)] recommends 48 to 102 inches for northern Ohio) to enhance vegetation survival during wet or extended dry periods.
**Utilize [http://chesapeakestormwater.net/wp-content/uploads/downloads/2014/03/Internal-Water-Storage-for-Bioretention-2009.pdf internal water storage]
+
**Utilize [https://epa.ohio.gov/static/Portals/41/storm_workshop/lid/IWS.Dec10.pdf internal water storage]
 
**Select vegetation that can be easily established but also provides potential for carbon sequestration. This includes incorporation of trees and shrubs into the design.
 
**Select vegetation that can be easily established but also provides potential for carbon sequestration. This includes incorporation of trees and shrubs into the design.
 
*Habitat improvement:
 
*Habitat improvement:
**Providing a littoral shelf for the growth of macrophytes in an infiltration system promotes healthier wildlife populations
+
**Utilize native, perennial vegetation, including shrubs and trees if space allows. For more information, see [[Minnesota plant lists]].
**Planting plants for pollinators in infiltration systems is an effective area to establish healthier pollinator colonies  — link to pollinator page
+
**Incorporate landscape features, such as form, plant layering, and plant density. For more information on landscape factors, see [https://scisoc.confex.com/scisoc/2015am/webprogram/Paper91320.html this presentation] by Dr. Steven Rodie (University of Nebraska at Omaha)
 +
**Maximize leaf/plant litter depth and the number of plant taxa
 +
**Consider shape and size to create larger interior habitats
 +
**Evaluate adjacent plant communities for compatibility with proposed bioretention area species. Identify nearby vegetated areas that are dominated by nonnative invasive species.
 +
**Promote soil (media) that maximizes habitat for invertebrate. This includes adjusting pH, limiting the amount of gravel, and promoting development of organic matter. See [http://www.sciencedirect.com/science/article/pii/S0169204609001029 Kazemi et al.] (2009) for more information.
 +
{{alert|Biofiltration practices (bioretention with an underdrain) may export phosphorus. Select an appropriate mix or add amendments that attenuate phosphorus to the design.|alert-warning}}
 +
[[File:Bioretention facility in St Paul MN.PNG|right|thumb|300 px|alt=This is a picture of Bioretention facility in St Paul MN|<font size=3>Bioretention practices can be incorporated into street landscapes. These bioretention practices include a variety of plants and are incorporated into a setting that includes mature trees, providing variety and contrast. Image Courtesy of Emmons & Olivier Resources, Inc.</font size>]]
 
*Community livability:
 
*Community livability:
 
**Include recreational infrastructure and interpretative signs
 
**Include recreational infrastructure and interpretative signs
**Construct the infiltration system in a way that ensures safety and perceived safety of the area. A few examples would be to use shallower infiltration systems to avoid child accidents, attracting pollinators that are appropriate for the nearby community, or planting shrubs, fencing, or vegetation that prevents people from entering the system
+
**Construct the infiltration system in a way that ensures safety and perceived safety of the area. A few examples would be to use shallower infiltration systems to avoid child accidents, attracting [https://stormwater.pca.state.mn.us/index.php?title=Pollinator_friendly_Best_Management_Practices_for_stormwater_management pollinators] that are appropriate for the nearby community, or planting shrubs, fencing, or vegetation that prevents people from entering the system
 
**Conduct surveys prior to and after development to identify community desires and construct features that enhance education, recreation, and other benefits of infiltration
 
**Conduct surveys prior to and after development to identify community desires and construct features that enhance education, recreation, and other benefits of infiltration
 
**Develop conveyance systems in such a way to minimize changes in temperature that can be detrimental to wildlife such a temperature sensitive fish
 
**Develop conveyance systems in such a way to minimize changes in temperature that can be detrimental to wildlife such a temperature sensitive fish
 
*Health benefits:
 
*Health benefits:
**Infiltration that incorporates landscaping principles reduce heat stress associate with heat islands (Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation (epa.gov))
+
**Infiltration that incorporates landscaping principles reduce heat stress associate with heat islands ([https://www.epa.gov/sites/default/files/2014-06/documents/treesandvegcompendium.pdf Reducing Urban Heat Islands: Compendium of Strategies - Trees and Vegetation])
**Infiltration that incorporates landscaping principles increases the mental health of the communities that use the area (What are the physical and mental benefits of gardening? - MSU Extension)
+
**Infiltration that incorporates landscaping principles increases the mental health of the communities that use the area ([https://www.canr.msu.edu/news/what_are_the_physical_and_mental_benefits_of_gardening What are the physical and mental benefits of gardening? Darnton and McGuire, 2014])
 
**Infiltration systems naturally control mosquito habitats by going dry within a few days compared to stormwater ponds
 
**Infiltration systems naturally control mosquito habitats by going dry within a few days compared to stormwater ponds
 
*Economic benefits and savings:
 
*Economic benefits and savings:
**Properly designed infiltration can prevent downstream cleanup costs
 
 
**Infiltration systems that incorporate desired landscape vegetation may increase property aesthetics and value
 
**Infiltration systems that incorporate desired landscape vegetation may increase property aesthetics and value
 +
**Choose the correct infiltration bmp. This includes both the type of practice (infiltration trench or basin, underground infiltration, bioinfiltration, tree trench, permeable pavement), sizing (multiple smaller practices vs. a larger practice0, and design considerations for the chosen practice. For more information see the design considerations on the following pages.
 +
***[[Green Infrastructure benefits of bioretention]]
 +
***[[Green Infrastructure benefits of tree trenches and tree boxes]]
 +
***[[Green Infrastructure benefits of permeable pavement]]
  
 
==Recommended reading==
 
==Recommended reading==
 +
*[https://www.risc.solutions/wp-content/uploads/2021/08/Design-Guide-for-Green-Infrastructure-BMPs-RISC-Report-August-2021.pdf A Design Guide for Green Stormwater Infrastructure Best Management Practices]. Jack Eskin, Tom Price, Jason Cooper, William Schleizer; 2014.
 
*[https://stormwaterbook.safl.umn.edu/infiltration-practices Stormwater Treatment: Assessment and Maintenance - Infiltration Practices]. University of Minnesota, St. Anthony Falls Laboratory.
 
*[https://stormwaterbook.safl.umn.edu/infiltration-practices Stormwater Treatment: Assessment and Maintenance - Infiltration Practices]. University of Minnesota, St. Anthony Falls Laboratory.
 
*[https://www.epa.gov/sites/default/files/2015-10/documents/brownfield_infiltration_decision_tool.pdf Implementing Stormwater Infiltration Practices at Vacant Parcels and Brownfield Sites]. US EPA Publication Number 905F13001, July 2013.
 
*[https://www.epa.gov/sites/default/files/2015-10/documents/brownfield_infiltration_decision_tool.pdf Implementing Stormwater Infiltration Practices at Vacant Parcels and Brownfield Sites]. US EPA Publication Number 905F13001, July 2013.
Line 114: Line 125:
 
*Darnton, J., and L. McGuire. 2014. [https://www.canr.msu.edu/news/what_are_the_physical_and_mental_benefits_of_gardening What are the physical and mental benefits of gardening?]. Michigan State University Extension.
 
*Darnton, J., and L. McGuire. 2014. [https://www.canr.msu.edu/news/what_are_the_physical_and_mental_benefits_of_gardening What are the physical and mental benefits of gardening?]. Michigan State University Extension.
 
*Gonzalez-Meler, M.A., L. A. Cotner, D. A. Massey, M. L. Zellner, and E. S. Minor. 2013. [https://indigo.uic.edu/articles/journal_contribution/The_Environmental_and_Ecological_Benefits_of_Green_Infrastructure_for_Stormwater_Runoff_in_Urban_Areas/10770875 Ecology and Evolution Group, Department of Biological Scienc The Environmental and Ecological Benefits of Green Infrastructure for Stormwater Runoff in Urban Areas].  
 
*Gonzalez-Meler, M.A., L. A. Cotner, D. A. Massey, M. L. Zellner, and E. S. Minor. 2013. [https://indigo.uic.edu/articles/journal_contribution/The_Environmental_and_Ecological_Benefits_of_Green_Infrastructure_for_Stormwater_Runoff_in_Urban_Areas/10770875 Ecology and Evolution Group, Department of Biological Scienc The Environmental and Ecological Benefits of Green Infrastructure for Stormwater Runoff in Urban Areas].  
*Ossola, A., A. K. H. Hahs, S. J. Livesley. 2015. ''Habitat complexity influences fine scale hydrological processes and the incidence of stormwater runoff in managed urban ecosystems''. Journal of Environmental Management. https://doi.org/10.1016/j.jenvman.2015.05.002.
+
*New York City's Mayor’s Office of Resiliency. 2020. [https://www1.nyc.gov/assets/orr/pdf/NYC_Climate_Resiliency_Design_Guidelines_v4-0.pdf Climate Resiliency Design Guidelines - Version 4.0]
Volume 159, Pages 1-10
+
*Ossola, A., A. K. H. Hahs, S. J. Livesley. 2015. ''Habitat complexity influences fine scale hydrological processes and the incidence of stormwater runoff in managed urban ecosystems''. Journal of Environmental Management. Volume 159, Pages 1-10. https://doi.org/10.1016/j.jenvman.2015.05.002.
 
*Shahzad, H., B.Myers, J.Boland, G.Hewa, and T.Johnson. 2022. ''Stormwater runoff reduction benefits of distributed curbside infiltration devices in an urban catchment''. Water Research Volume 215. https://doi.org/10.1016/j.watres.2022.118273.
 
*Shahzad, H., B.Myers, J.Boland, G.Hewa, and T.Johnson. 2022. ''Stormwater runoff reduction benefits of distributed curbside infiltration devices in an urban catchment''. Water Research Volume 215. https://doi.org/10.1016/j.watres.2022.118273.
 
*US EPA. [https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands]. Accessed November 9, 2022.
 
*US EPA. [https://www.epa.gov/heatislands/using-trees-and-vegetation-reduce-heat-islands Using Trees and Vegetation to Reduce Heat Islands]. Accessed November 9, 2022.
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*[https://stormwater.pca.state.mn.us/index.php?title=Understanding_and_interpreting_soils_and_soil_boring_reports_for_infiltration_BMPs Understanding and interpreting soils and soil boring reports for infiltration BMPs]
 
*[https://stormwater.pca.state.mn.us/index.php?title=Understanding_and_interpreting_soils_and_soil_boring_reports_for_infiltration_BMPs Understanding and interpreting soils and soil boring reports for infiltration BMPs]
 
*[https://stormwater.pca.state.mn.us/index.php?title=Determining_soil_infiltration_rates Determining soil infiltration rates]
 
*[https://stormwater.pca.state.mn.us/index.php?title=Determining_soil_infiltration_rates Determining soil infiltration rates]
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[[Category:Level 2 - Management/Green infrastructure]]
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[[Category:Level 3 - Best management practices/Structural practices/Infiltration (trench/basin)]]

Latest revision as of 19:32, 31 January 2023

image
Photo illustrating permeable interlocking pavement. Permeable interlocking pavers consist of concrete or stone units with open, permeable spaces between the units.
Photo illustrating permeable interlocking concrete pavement.
photo of a rain garden
Bioinfiltration (rain garden) in a residential development. Photo courtesy of Katherine Sullivan.

Infiltration is the practice of draining water into soils, typically through engineered systems such as bioinfiltration (rain gardens), infiltration basins, dry swales with check dams, and permeable pavement. The practice of infiltration is beneficial for soils, maintaining natural hydrology, and has a significant water quality impact for downstream lakes, rivers, and ponds. Depending on design, stormwater infiltration practices can be a key component of green infrastructure (GI) to promote the health and well-being of animals, vegetation, and the people that rely upon these waters when designing sites.

Some of the more common infiltration practices include

For further reading on different types of infiltration, see Stormwater infiltration Best Management Practices and BMPs for stormwater infiltration.

Warning: On sites where the Construction Stormwater General Permit applies, infiltration may be prohibited due to site conditions. For more information, see When infiltration is not authorized under a stormwater permit

Green infrastructure and multiple benefits

Green infrastructure (GI) encompasses a wide array of practices, including stormwater management. Green stormwater infrastructure (GSI) encompasses a variety of practices primarily designed for managing stormwater runoff but that provide additional benefits such as habitat or aesthetic value.

There is no universal definition of GI or GSI (link here for more information). Consequently, the terms are often interchanged, leading to confusion and misinterpretation. GSI practices are designed to function as stormwater practices first (e.g. flood control, treatment of runoff, volume control), but they can provide additional benefits. Though designed for stormwater function, GSI practices, where appropriate, should be designed to deliver multiple benefits (often termed "multiple stacked benefits". For more information on green infrastructure, ecosystem services, and sustainability, link to Multiple benefits of green infrastructure and role of green infrastructure in sustainability and ecosystem services.

Benefit Effectiveness Notes
Water quality
Most pollutants are retained in the engineered media, soil, or vadose zone. If transported to groundwater, concentrations of most pollutants are below water quality standards. Chloride is an exception.
Water quantity/supply
Can provide effective flood control for small- and medium-intensity storms.
Energy savings
Climate resiliency
Flood control. Impacts on carbon sequestration are uncertain.
Air quality
Habitat improvement
Use of perennial vegetation and certain media mixes promote invertebrate communities, pollinators, birds, and potentially small mammals.
Community livability
When vegetation is incorporated, aesthetically pleasing and can be incorporated into a wide range of land use settings.
Health benefits
Economic savings
Generally provide cost savings vs. conventional practices over the life of the practice.
Macroscale benefits
Macroscale effects depend on the size of the practice. Some infiltration practices, typically underground or tree trench systems, can be very large and have macroscale benefits.
Level of benefit: ◯ - none; - small; - moderate; - large; - very high

Green Infrastructure benefits of infiltration practices

  • Water quality: Stormwater infiltration practices are excellent water quality treatment practices. Engineered media, soils, and the underlying vadose zone provide effective retention of most pollutants (see Minimum bioretention soil media depths recommended to target specific stormwater pollutants). Chloride and nitrate are exceptions, though concentrations of these are generally below water quality standards except for chloride during deicing season. Infiltration should be avoided in areas where contaminants in soil or groundwater may be mobilized by infiltrating water. For more information, see Surface water and groundwater quality impacts from stormwater infiltration
  • Water quantity and hydrology: Infiltration practices reduce the volume of stormwater runoff and retard peak flow from rainfall events, thus reducing flood potential in areas downstream of the practice. They are most effective for small- and medium-intensity rain and runoff events unless sized to meet larger events. Infiltration promotes groundwater recharge, potentially increasing baseflow and/or recharge of deeper aquifers.
  • Energy savings: Larger infiltration practices that incorporate trees and provide shade reduce air conditioning costs. Since infiltration reduces stormwater runoff, they help prevent road deterioration and reduce maintenance costs (Using Trees and Vegetation to Reduce Heat Islands;US EPA).
  • Air quality: Benefits of infiltration practices are largely indirect, such as sequestration of carbon and other greenhouse gasses. Carbon sequestration is generally insignificant unless vegetation is incorporated into the practice and the soil or engineered media promotes biologic activity.
  • Climate resiliency: Properly installed infiltration practices reduce the impact of flooding during rainfall events, particularly small- and medium-sized events. Vegetated infiltration systems promote photosynthesis and carbon sequestration. Incorporation of larger plants such as trees or vegetation that provides shade reduces effects of heat islands (Using Trees and Vegetation to Reduce Heat Islands;US EPA).
  • Habitat improvement: Infiltration results in decreased runoff and erosion, which increases soil stability. This promotes vegetation growth that further stabilizes a site and creates habitat for birds, pollinator insects, and potentially small mammals. Soil or media may be engineered to promote invertebrate activity. Reduced runoff associated with increased infiltration reduces adverse effects of elevated temperatures that harm coldwater organisms.
  • Community livability: Infiltration that results in groundwater recharge and improved baseflow provides increased recreational opportunities and helps ensure safe and healthy access to water sources. Incorporating aesthetically pleasing landscaping when planning infiltration systems may help improve mental health of the site users (What are the physical and mental benefits of gardening? - Michigan State University Extension). Large infiltration practices that incorporate trees into the design provide shade that can reduce air temperatures (Reducing Urban Heat Islands: Compendium of Strategies: Trees and Vegetation; EPA).
  • Health benefits: Infiltration provides cleaner waterways through the reduction of nutrients, pathogens, metals, TSS, and phosphorus and provides healthier environments to the humans, wildlife, and vegetation that use these waters.
  • Economic benefits and savings: In addition to water quality and flood control benefits (Braden and Johnston, 2004), properly designed infiltration can prevent downstream cleanup costs. Well maintained infiltration systems combined with vegetation may increase property aesthetics and property value. Properly designed and functioning infiltration systems reduce downstream infrastructure costs (Braden and Johnston, 2004).

Design considerations

Maximizing specific green infrastructure (GI) benefits of constructed areas requires design considerations prior to installation. While site limitations cannot always be overcome, the following recommendations for a designer are given to maximize the GI benefit. In addition to the following information, many design considerations applicable to bioretention should be considered for infiltration practices.

Caution: The following discussion focuses on design considerations. All benefits delivered by the practice require appropriate construction, operation, and maintenance of the practice. O&M considerations should be included during the design phase of a project. For information on O&M for GSI practices, see Operation and maintenance of green stormwater infrastructure best management practices
  • Water quality
    • Follow appropriate design guidance to maximize capture of runoff. Consider local climate characteristics (Gonzalez-Meler et al., 2013), which may affect the type and design characteristics of a practice.
    • Design infiltration basins to minimize short-circuiting that results in water bypassing the treatment zones in the practice. Deep macropores may lead to short-circuiting but may be desirable for maximizing infiltration volume. If macropore development is encouraged, ensure water preferentially transported vertically receives appropriate treatment by ensuring underlying soils can effectively treat pollutants.
    • Infiltration systems with ecological diversity can help promote water quality treatment through effective uptake of pollutants (e.g. nutrients) or through breakdown of pollutants (e.g. promote microbiologic breakdown, such as by ensuring a food source (e.g. organic matter) and oxygenated environment). Diversifying the vegetation will remove a wider range of pollutants and maximize the water treatment
    • Ensure adequate pretreatment
    • Design the infiltration system to minimize effects of groundwater (e.g. elevated groundwater table), mounding beneath the system, and intersection with underlying sewer systems (Thompson et. al, 2021).
  • Water quantity and hydrology:
    • Follow appropriate design guidance to maximize capture of runoff. Consider local climate characteristics (Gonzalez-Meler et al., 2013).
    • Promoting macropore development results in increased infiltration. Macropores are associated with vegetation and increased invertebrate activity. These can be enhanced through use of deep-rooted perennial vegetation and organic-rich engineered media or soil (Ossola et. al, 2015).
    • Distributed infiltration systems throughout an area site typically provide increased hydrologic capacity, partly as a result of reducing the risk and impacts of system failure. One way to increase distribution of infiltration systems is to encourage infiltration on individual parcels (Cadavid and Ando, 2013; Shahzad et al., 2022).
    • Maximize water storage by manipulating the media and incorporating internal storage.
    • Increase the size of infiltration systems, if feasible, to maximize capture of runoff.
  • Climate resiliency:
    • To reduce heat island effects, select vegetation that reflects solar energy, absorbs solar energy and releases it slowly, or that maximizes evapotranspiration (NYC Mayor’s Office of Recovery and Resiliency).
    • Oversize bowl depth (storage) to account for increased precipitation. Winston (2016) recommends oversizing by 33-45% for bioretention in northern Ohio. Oversizing can also be accomplished by reducing loading to individual bioretention practices.
    • Establish thicker media depths (Winston (2016) recommends 48 to 102 inches for northern Ohio) to enhance vegetation survival during wet or extended dry periods.
    • Utilize internal water storage
    • Select vegetation that can be easily established but also provides potential for carbon sequestration. This includes incorporation of trees and shrubs into the design.
  • Habitat improvement:
    • Utilize native, perennial vegetation, including shrubs and trees if space allows. For more information, see Minnesota plant lists.
    • Incorporate landscape features, such as form, plant layering, and plant density. For more information on landscape factors, see this presentation by Dr. Steven Rodie (University of Nebraska at Omaha)
    • Maximize leaf/plant litter depth and the number of plant taxa
    • Consider shape and size to create larger interior habitats
    • Evaluate adjacent plant communities for compatibility with proposed bioretention area species. Identify nearby vegetated areas that are dominated by nonnative invasive species.
    • Promote soil (media) that maximizes habitat for invertebrate. This includes adjusting pH, limiting the amount of gravel, and promoting development of organic matter. See Kazemi et al. (2009) for more information.
Caution: Biofiltration practices (bioretention with an underdrain) may export phosphorus. Select an appropriate mix or add amendments that attenuate phosphorus to the design.
This is a picture of Bioretention facility in St Paul MN
Bioretention practices can be incorporated into street landscapes. These bioretention practices include a variety of plants and are incorporated into a setting that includes mature trees, providing variety and contrast. Image Courtesy of Emmons & Olivier Resources, Inc.
  • Community livability:
    • Include recreational infrastructure and interpretative signs
    • Construct the infiltration system in a way that ensures safety and perceived safety of the area. A few examples would be to use shallower infiltration systems to avoid child accidents, attracting pollinators that are appropriate for the nearby community, or planting shrubs, fencing, or vegetation that prevents people from entering the system
    • Conduct surveys prior to and after development to identify community desires and construct features that enhance education, recreation, and other benefits of infiltration
    • Develop conveyance systems in such a way to minimize changes in temperature that can be detrimental to wildlife such a temperature sensitive fish
  • Health benefits:
  • Economic benefits and savings:

Recommended reading

References

Related pages

Additional References from the Minnesota Stormwater Manual

This page was last edited on 31 January 2023, at 19:32.