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{{alert|This page is an edit and testing page use by the wiki authors.  It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.|alert-danger}}
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[[File:General information page image.png|right|100px|alt=image]]
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[[File:Pdf image.png|100px|thumb|right|alt=pdf image|<font size=3>[https://stormwater.pca.state.mn.us/index.php?title=File:Green_Infrastructure_benefits_of_permeable_pavement_-_Minnesota_Stormwater_Manual.pdf Download pdf]</font size>]]
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[[File:Permeable interlocking concrete pavement cross section.jpg|thumb|300 px|alt=This schematic illustrates typical permeable interlocking concrete pavement cross section and basic components of a pervious concrete system|<font size=3>Schematic illustrating typical permeable interlocking concrete pavement cross section and basic components of a pervious concrete system.</font size>]]
  
[permeable pavement picture profile]
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<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 pavements]'''</span> allow stormwater runoff to filter through surface voids into an underlying stone reservoir where it is temporarily stored and/or <span title="Infiltration Best Management Practices (BMPs) treat urban stormwater runoff as it flows through a filtering medium and into underlying soil, where it may eventually percolate into groundwater. The filtering media is typically coarse-textured and may contain organic material, as in the case of bioinfiltration BMPs."> [https://stormwater.pca.state.mn.us/index.php?title=Stormwater_infiltration_Best_Management_Practices '''infiltrated''']</span>.
  
==Green infrastructure and multiple benefits==
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While designs vary, all permeable pavements have a similar structure, consisting of a surface pavement layer, an underlying stone aggregate reservoir layer, optional <span title="An underground drain or trench with openings through which the water may percolate from the soil or ground above"> '''underdrains'''</span>, and geotextile over uncompacted soil subgrade. From a hydrologic perspective, permeable pavement is typically designed to manage rainfall landing directly on the permeable pavement surface area. Permeable pavement surface areas may accept runoff contributed by adjacent impervious areas such as driving lanes or rooftops. Runoff from adjacent vegetated areas must be stabilized and not generating sediment as its transport accelerates permeable pavement surface clogging. Additionally, the capacity of the underlying reservoir layer limits the <span title="The total drainage area, including pervious and impervious surfaces, contributing to a BMP"> '''[https://stormwater.pca.state.mn.us/index.php?title=Contributing_drainage_area_to_stormwater_BMPs contributing drainage area]'''</span>.  
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.
 
  
==Permeable pavement==
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Permeable pavement can be used in conjunction with other stormwater measures to ensure maximum benefit. Examples include
Permeable pavement is a beneficial technology for stormwater management. This technology is highly beneficial for long term soil and water preservation of a site and has significant water quality impact for downstream systems such as lakes, rivers, and ponds. This technology operates by allowing water to flush quickly through pavement systems that would otherwise act as a conveyance system and remove water from a site. This water is instead drained directly downward through the pavement and into the ground underneath.
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*permeable pavement built with underground cisterns, vaults, or other treatment devices;
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*permeable pavement used with <span title="Rain water harvesting is the practice of collecting rain water from impermeable surfaces, such as rooftops, and storing for future use."> '''[https://stormwater.pca.state.mn.us/index.php?title=Stormwater_and_rainwater_harvest_and_use/reuse harvest and reuse]'''</span> systems for irrigation;
 +
*increased vegetation options at a site due to increased groundwater accessibility; and
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*systems in which other infiltration methods are difficult to achieve or may cause detrimental effects.
  
When designing a system, it is recommended to determine if permeable pavement would be feasible. Smaller sites may not see as much benefit due to lower runoff volumes but roadways, parking lots, and any other appropriate paved surface may benefit from this. Permeable pavement can be used in conjunction with other stormwater measures to ensure maximum benefit. Some key examples are:
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Different types of permeable pavement include
*Permeable pavement built with underground cisterns, vaults, or other treatment devices
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*interlocking pavers,
*Permeable pavement used with irrigation stormwater reuse
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*pervious concrete,
*Increased vegetation options at a site due to increased groundwater accessibility
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*porous asphalt, and
*Systems in which other infiltration methods are difficult to achieve or may cause detrimental effects
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*plastic grid pavers
  
Different types of permeable pavement include:
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Permeable pavement can also be used to increase the safety of a site as it has been shown to increase traction and prevent ice accumulation on roadways during adverse weather [https://www.usgs.gov/centers/upper-midwest-water-science-center/science/evaluating-potential-benefits-permeable-pavement (USGS)].
*Interlocking pavers
 
*Pervious concrete
 
*Porous asphalt
 
*Plastic grid pavers
 
  
—insert pictures of permeable pavement types--
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For more information on permeable pavements [https://stormwater.pca.state.mn.us/index.php?title=Permeable_pavement please click here].
  
With this in mind, permeable pavement can also be used to increase the safety of a site as it has been shown to increase traction for roadways during adverse weather and when used in outdoor sporting courts such as tennis and basketball, it can help prevent injuries by reducing the water that pools on the site.
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==Green infrastructure and multiple benefits==
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<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.
  
For more information on how permeable pavements work please click here.
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There is no universal definition of GI or GSI ([https://stormwater.pca.state.mn.us/index.php?title=Green_infrastructure_and_green_stormwater_infrastructure_terminology 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]].
  
==Green Infrastructure benefits of infiltration practices==
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{| class="wikitable" style="float:right; margin-left: 10px; width:500px;"
Water quality: Pollutants are removed through stormwater runoff reduction when permeable pavement is used. This allows for vegetation and biota growth, vegetative filtering, and soil adsorption when rainfall events occur at the site.
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|-
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! Benefit !! Effectiveness !! Notes
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|-
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| Water quality || <font size=4><center>&#9685;</center></font size> || Benefits are maximized for bioinfiltration. Biofiltration may export phosphorus if not designed properly.
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|-
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| Water quantity/supply || <font size=4><center>&#9685;</center></font size> || Bioinfiltration helps mimic natural hydrology. Some rate control benefit.
 +
|-
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| Energy savings || <font size=4><center>&#9684;</center></font size> ||
 +
|-
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| Climate resiliency || <font size=4><center>&#9684;</center></font size> || Provides some rate control. Impacts on carbon sequestration are uncertain.
 +
|-
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| Air quality || <center>&#9684;</center> ||
 +
|-
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| Habitat improvement || <center>&#9711;</center> || Use of perennial vegetation and certain media mixes promote invertebrate communities.
 +
|-
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| Community livability || <font size=4><center>&#9684;</center></font size> || Aesthetically pleasing and can be incorporated into a wide range of land use settings.
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|-
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| Health benefits || <font size=4><center>&#9684;</center></font size> ||
 +
|-
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| Economic savings || <font size=4><center>&#9684;</center></font size> || Generally provide cost savings vs. conventional practices over the life of the practice.
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|-
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|Macroscale benefits || <font size=4><center>&#9684;</center></font size> || Individual bioretention practices are typically microscale, but multiple bioretention practices, when incorporated into a landscape design, provide macroscale benefits such as wildlife corridors.
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|-
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| colspan="3" | Level of benefit: &#9711; - none; <font size=4>&#9684;</font size>; - small; <font size=4>&#9681;</font size> - moderate; <font size=4>&#9685;</font size> - large; <font size=6>&#9679;</font size> - very high
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|}
  
Water quantity and hydrology: Reduction in total water volume movement and retardation of peak flow from rainfall events. Helps protect from downstream flooding and can be used in conjunction with reuse systems to reduce required water consumption for onsite irrigation. Infiltration also will recharge local groundwater.
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==Green Infrastructure benefits of permeable pavement==
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*[https://stormwater.pca.state.mn.us/index.php?title=Water_quality_benefits_of_Green_Stormwater_Infrastructure '''Water quality''']: Pollutants are removed through stormwater runoff reduction via infiltration. Permeable pavements are very effective infiltration practices though they typically are small in size and require frequent maintenance.
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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''']: Permeable pavement provides reduction in total water volume movement and retardation of peak flow from rainfall events. Helps protect from downstream flooding and can be used in conjunction with reuse systems to reduce required water consumption for onsite irrigation. Infiltration also recharges local groundwater.
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*'''Energy''': Though permeable pavements are typically energy intensive during the construction phase, life cycle cost studies suggest they can provide energy savings once built. These savings are associated with reduced requirements for treatment, water savings, reduced snow and ice maintenance. Permeable pavements can also be combined with other energy saving practices, such as harvest and reuse, and with energy supply practices, such as ground source heat pumps (Antunes et al., 2018; Coupe et al., 2009; Hui et al., 2020; Imran et al., 2013; Wang et al., 2018).
 +
*[https://stormwater.pca.state.mn.us/index.php?title=Air_quality_benefits_of_Green_Stormwater_Infrastructure '''Air quality''']: In areas adjacent to permeable pavements, reduced use of deicers decreases salt dispersion via air pathways. Permeable pavements may result in lower air emissions associated with traffic and snow clearing equipment.
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*[https://stormwater.pca.state.mn.us/index.php?title=Climate_benefits_of_Green_Stormwater_Infrastructure '''Climate resiliency''']: Helps alleviate the impact on flooding for small- and medium-intensity storms and runoff events. Saves water when combined with reuse systems.
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*[https://stormwater.pca.state.mn.us/index.php?title=Wildlife_habitat_and_biodiversity_benefits_of_Green_Stormwater_Infrastructure '''Habitat improvement''']: Permeable pavement provides minimal habitat benefit, but can be combined with vegetative systems. Reduction in water temperature changes as a result of volume flow reduction.
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*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Community livability''']: Well designed permeable pavement practices helps to protect recreation sites for people by ensuring safe and healthy access to water sources. Permeable pavements can be aesthetically pleasing and provide safety features compared to traditional pavements ([https://www.epa.gov/heatislands/using-cool-pavements-reduce-heat-islands#:~:text=Benefits%20and%20Costs&text=Reduced%20stormwater%20runoff%20and%20improved,reducing%20runoff%20and%20filtering%20pollutants. US EPA]).
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*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Health benefits''']: Water quality benefits associated with reduction of nutrients, pathogens, metals, TSS, and phosphorus via infiltration. Provides improved safety features compared to traditional pavements by infiltrating water quickly through the pavement, less pooling of water, and reduced ice formation. Minimizes mosquito breeding by avoiding standing water on site.
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*[https://stormwater.pca.state.mn.us/index.php?title=Social_benefits_of_Green_Stormwater_Infrastructure '''Economic savings''']: In addition to water quality and flood control benefits, properly installed permeable pavers can prevent downstream cleanup needs. Permeable pavement can increase property aesthetics that increase property value, particularly when combined with vegetated systems.
  
Energy: Main energy savings comes from reduced energy requirements for wastewater treatment.
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==Design considerations==
 
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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 are given to maximize the GI benefit.
Air quality: Benefits are largely indirect, such as carbon sequestration.
 
 
 
Climate resiliency: Alleviates the impact on flooding, saves water through reuse systems, reduction of downstream pollutant loading
 
 
 
Habitat improvement: Reduction of soil erosion and increased soil stability promotes vegetation growth. Reduction in water temperature changes as a result of volume flow reduction. Retention of water on site helps ensure available water for vegetation and wildlife.
 
 
 
Community livability: Well designed permeable pavement practices helps to protect recreation sites for people by ensuring safe and healthy access to water sources. Water quality benefits from permeable pavement promote healthy water sources for diverse vegetation growth. This diversity allows for more heterogeneous plant growth and if the water quality is good enough, gardening practices of the local community may not be impacted. Reduction in water on surface ways helps improve safety for driving and human use.
 
 
 
Health benefits: Reduction of nutrients, pathogens, metals, TSS, and phosphorus among others. Increased longevity for fish and wildlife in the area through the reduction of compounds that would be washed into waterways as rain runoff.  
 
  
Economic benefits and savings: In addition to water quality and flood control benefits, properly installed permeable pavers can prevent downstream cleanup needs. Permeable pavement that benefits vegetation can increase property aesthetics that increase property value.
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{{alert|Permeable pavement SHOULD NOT be used in areas of high traffic volume, with heavy equipment, or with frequent start and stopping|alert-warning}}
  
==Design considerations==
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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}}
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 are given to maximize the GI benefit.
 
  
Note: Permeable pavement SHOULD NOT be used in areas of high traffic volume, with heavy equipment, or with frequent start and stopping. --- Maybe add an illustration of a treatment train involving permeable pavement
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[[File:PPment sign.png|300px|thumb|alt=permeable pavement sign|<font size=3>Example sign to be placed adjacent to permeable pavements. Source: [https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwater/BMP%20Manual/C-5%20%20Permeable%20Pavement%2004-06-17.pdf North Caroline Department of Environmental Quality].</font size>]]
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[[File:Central corridor final.jpg|thumb|300px|alt=photo for tree trench system, Central Corridor Light rail project|<font size=3>Photo of the completed tree system for the Central Corridor Light Rail Transit project, St. Paul, Minnesota. This system combines permeable pavement with a tree trench system. Image courtesy of the [http://www.capitolregionwd.org/ Capitol Region Watershed District].</font size>]]
  
*Water quality
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*Water quality and water quantity/hydrology: These benefits are combined since permeable pavement design focuses on infiltration, with the subsoil having less impact on pollutant retention compared to other infiltration practices such as bioinfiltration, where organic matter can be incorporated into the design.
**Place the permeable pavement in a location where the majority of water flows through or to
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**Ensure the subgrade is flat. Since roads are typically sloped, utilize terracing in the subgrade to achieve flat slopes. See [https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwater/BMP%20Manual/C-5%20%20Permeable%20Pavement%2004-06-17.pdf page 5 of the North Carolina design guidance].
**Design to maximize retention time and prevent short-circuiting
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**Incorporate signage into the design to ensure maintenance activities do not affect the infiltration properties of the pavement.
**Plan for the expected loading on the permeable pavement and ensure capabilities versus use line up
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**Design to maximize retention time and prevent short-circuiting. Storage may be increased by use of geotextile subgrades. An example is presented by Nnadi et al, (2014).
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**Plan for the expected loading on the permeable pavement and ensure capabilities and reduce compaction or clogging
 
**Use in conjunction with other treatments to establish a treatment train or reuse water on site
 
**Use in conjunction with other treatments to establish a treatment train or reuse water on site
*Water quantity and hydrology:
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**Some research has been conducted into use of geotextiles and other amendments for enhancing water quality treatment. See Ostrom and Davis (2019) and Nnadi et al. (2014).
**Permeable pavement can significantly reduce the runoff and can be used to meet the water quality volume treatment requirement per the Construction Stormwater Permit
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*Energy:
 +
**If feasible incorporate energy sources into the design, such as solar arrays and ground source heat pump systems
 
*Climate resiliency:
 
*Climate resiliency:
 
**Established systems using permeable pavement reduces the runoff impact on surrounding waterways through decreased pollutant loads and increased infiltration
 
**Established systems using permeable pavement reduces the runoff impact on surrounding waterways through decreased pollutant loads and increased infiltration
 
**Permeable pavement systems can be established to support vegetation through water reuse systems, promoting further enhancement of water
 
**Permeable pavement systems can be established to support vegetation through water reuse systems, promoting further enhancement of water
*Habitat improvement:
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**Use light colored pavements to reflect incoming solar energy and reduce heat island effects
**Reduction in chlorides needed as water infiltrates through relatively quickly when melted
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*Habitat improvement: Permeable pavement has minimal benefit for habitat but can be combined with vegetated practices. See habitat benefits for [https://stormwater.pca.state.mn.us/index.php?title=Green_Infrastructure_benefits_of_bioretention bioretention], [https://stormwater.pca.state.mn.us/index.php?title=Green_Infrastructure_benefits_of_tree_trenches_and_tree_boxes tree trenches], and [https://stormwater.pca.state.mn.us/index.php?title=Green_Infrastructure_benefits_of_vegetated_swales swales].
 
*Community livability:
 
*Community livability:
**Community members, depending on the system used, will likely not even realize the system is in place
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**When appropriate and feasible, incorporate vegetated practices or harvest and reuse systems (see Beechem et al., 2010) into the design to improve aesthetics and provide additional water quality and quantity benefits.
**Development of permeable systems can promote mental health through better vegetation from the increased water storage and erosion reduction on site
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**Incorporation of vegetation promotes mental health
**Develop conveyance systems in such a way to minimize changes in temperature that can be detrimental to wildlife populations
 
 
*Health benefits:
 
*Health benefits:
**Safety of community is improved by water infiltrating quickly through the pavement, less pooling of water and ice means less slipping hazards
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**Choose pavements to maximize traction in cold climates
**Minimizes mosquito by reducing standing water on site that impermeable pavement would otherwise offer
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**Use light colored pavements to reflect incoming solar energy and reduce heat island effects
**Economic benefits and savings:
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*Economic benefits and savings:
 
**Reduction in maintenance cost for vegetation if water reuse system is used in conjunction with permeable pavement
 
**Reduction in maintenance cost for vegetation if water reuse system is used in conjunction with permeable pavement
**Reduction in land space required as the pervious area can serve a dual purpose for cement and treatment that would otherwise be ineligible for water quality volume treatment
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**Integrate vegetation into the landscape design to create habitat, pathways, picnic areas, etc.
**Integrates infiltration into landscape design, including creating habitat, pathways, picnic areas, etc.
 
 
 
Information regarding performance summaries of permeable pavement can be found here.
 
  
Additional general information on permeable pavement can be found here.
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==Recommended reading==
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*[https://www.mdpi.com/2071-1050/13/8/4509/htm A Systematic Review of the Hydrological, Environmental and Durability Performance of Permeable Pavement Systems] - Sambito et al., Sustainability, 13(8), 4509; https://doi.org/10.3390/su13084509
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*[https://www.usgs.gov/centers/upper-midwest-water-science-center/science/evaluating-potential-benefits-permeable-pavement Evaluating the potential benefits of permeable pavement on the quantity and quality of stormwater runoff] - United States Geological Survey
  
Additional considerations for permeable pavement can be found here.
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==References==
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*Antunes, L.N., E. Ghisi, and L.P. Thives. 2018. [https://www.mdpi.com/2073-4441/10/11/1575 Permeable Pavements Life Cycle Assessment: A Literature Review]. Water 2018, 10(11), 1575; https://doi.org/10.3390/w10111575.
 +
*Beecham, S., T. Lucke, and B. Myers. 2010. [https://www.researchgate.net/publication/265823466_Designing_Porous_and_Permeable_Pavements_for_Stormwater_Harvesting_and_Reuse Designing Porous and Permeable Pavements for Stormwater Harvesting and Reuse]. Conference: 1st European International Association for Hydro-Environment Engineering and Research (IAHR) ConferenceAt: Edinburgh.
 +
*Coupe, S. J., S. Charlesworth, and A.S. Faraj. 2009. [http://www.sept.org/techpapers/1446.pdf COMBINING PERMEABLE PAVING WITH RENEWABLE ENERGY DEVICES: INSTALLATION, PERFORMANCE AND FUTURE PROSPECTS]. 9th. International Conference on Concrete Block Paving. Buenos Aires, Argentina, 2009/10/18-21 Argentinean Concrete Block Association (AABH) - Argentinean Portland Cement Institute (ICPA) Small Element Paving Technologists (SEPT).
 +
*Hui, J.L., L.Y. Wang, and H. Zhang. 2020. ''Integrated life cycle assessment of permeable pavement: Model development and case study''. Transportation Research Part D: Transport and Environment Volume 85, 102381. https://doi.org/10.1016/j.trd.2020.102381.
 +
*Imran, H.M., S. Akib, M.R. Karim. 2013. ''Permeable pavement and stormwater management systems: a review''. Environmental Technology, Volume 34, Issue 18. https://doi.org/10.1080/09593330.2013.782573.
 +
*Nnadi, E.O., S.J. Coupe, L.A. Sañudo-Fontaneda, and J. Rodriguez-Hernandez. 2014. ''An evaluation of enhanced geotextile layer in permeable pavement to improve stormwater infiltration and attenuation''. International Journal of Pavement Engineering, Volume 15, - Issue 10.
 +
*North Carolina Department of Environmental Quality. 2017. [https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwater/BMP%20Manual/C-5%20%20Permeable%20Pavement%2004-06-17.pdf NCDEQ Stormwater Design Manual; C-5 - permeable pavement].
 +
*Ostrom, T.K., A.P. Davis. 2019. [https://www.sciencedirect.com/science/article/pii/S0043135419308450 Evaluation of an enhanced treatment media and permeable pavement base to remove stormwater nitrogen, phosphorus, and metals under simulated rainfall]. Water Research, Volume 166, 115071. https://doi.org/10.1016/j.watres.2019.115071.
 +
*Wang, Y. H. Lia, A. Abdelhady, and J. Harvey. 2018. [https://www.sciencedirect.com/science/article/pii/S2046043017300862 Initial evaluation methodology and case studies for life cycle impact of permeability of permeable pavements]. International Journal of Transportation Science and Technology, Volume 7, Issue 3, Pages 169-178. https://doi.org/10.1016/j.ijtst.2018.07.002.
  
NOTE: It is highly recommended that permeable pavement should NOT be used in areas of high traffic volume, with heavy equipment, or with frequent start and stopping.
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[[Category:Level 2 - Management/Green infrastructure]]
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[[Category:Level 3 - Best management practices/Structural practices/Permeable pavement]]

Latest revision as of 21:23, 16 February 2023

image
This schematic illustrates typical permeable interlocking concrete pavement cross section and basic components of a pervious concrete system
Schematic illustrating typical permeable interlocking concrete pavement cross section and basic components of a pervious concrete system.

Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir where it is temporarily stored and/or infiltrated.

While designs vary, all permeable pavements have a similar structure, consisting of a surface pavement layer, an underlying stone aggregate reservoir layer, optional underdrains, and geotextile over uncompacted soil subgrade. From a hydrologic perspective, permeable pavement is typically designed to manage rainfall landing directly on the permeable pavement surface area. Permeable pavement surface areas may accept runoff contributed by adjacent impervious areas such as driving lanes or rooftops. Runoff from adjacent vegetated areas must be stabilized and not generating sediment as its transport accelerates permeable pavement surface clogging. Additionally, the capacity of the underlying reservoir layer limits the contributing drainage area.

Permeable pavement can be used in conjunction with other stormwater measures to ensure maximum benefit. Examples include

  • permeable pavement built with underground cisterns, vaults, or other treatment devices;
  • permeable pavement used with harvest and reuse systems for irrigation;
  • increased vegetation options at a site due to increased groundwater accessibility; and
  • systems in which other infiltration methods are difficult to achieve or may cause detrimental effects.

Different types of permeable pavement include

  • interlocking pavers,
  • pervious concrete,
  • porous asphalt, and
  • plastic grid pavers

Permeable pavement can also be used to increase the safety of a site as it has been shown to increase traction and prevent ice accumulation on roadways during adverse weather (USGS).

For more information on permeable pavements please click here.

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
Benefits are maximized for bioinfiltration. Biofiltration may export phosphorus if not designed properly.
Water quantity/supply
Bioinfiltration helps mimic natural hydrology. Some rate control benefit.
Energy savings
Climate resiliency
Provides some rate control. Impacts on carbon sequestration are uncertain.
Air quality
Habitat improvement
Use of perennial vegetation and certain media mixes promote invertebrate communities.
Community livability
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
Individual bioretention practices are typically microscale, but multiple bioretention practices, when incorporated into a landscape design, provide macroscale benefits such as wildlife corridors.
Level of benefit: ◯ - none; ; - small; - moderate; - large; - very high

Green Infrastructure benefits of permeable pavement

  • Water quality: Pollutants are removed through stormwater runoff reduction via infiltration. Permeable pavements are very effective infiltration practices though they typically are small in size and require frequent maintenance.
  • Water quantity and hydrology: Permeable pavement provides reduction in total water volume movement and retardation of peak flow from rainfall events. Helps protect from downstream flooding and can be used in conjunction with reuse systems to reduce required water consumption for onsite irrigation. Infiltration also recharges local groundwater.
  • Energy: Though permeable pavements are typically energy intensive during the construction phase, life cycle cost studies suggest they can provide energy savings once built. These savings are associated with reduced requirements for treatment, water savings, reduced snow and ice maintenance. Permeable pavements can also be combined with other energy saving practices, such as harvest and reuse, and with energy supply practices, such as ground source heat pumps (Antunes et al., 2018; Coupe et al., 2009; Hui et al., 2020; Imran et al., 2013; Wang et al., 2018).
  • Air quality: In areas adjacent to permeable pavements, reduced use of deicers decreases salt dispersion via air pathways. Permeable pavements may result in lower air emissions associated with traffic and snow clearing equipment.
  • Climate resiliency: Helps alleviate the impact on flooding for small- and medium-intensity storms and runoff events. Saves water when combined with reuse systems.
  • Habitat improvement: Permeable pavement provides minimal habitat benefit, but can be combined with vegetative systems. Reduction in water temperature changes as a result of volume flow reduction.
  • Community livability: Well designed permeable pavement practices helps to protect recreation sites for people by ensuring safe and healthy access to water sources. Permeable pavements can be aesthetically pleasing and provide safety features compared to traditional pavements (US EPA).
  • Health benefits: Water quality benefits associated with reduction of nutrients, pathogens, metals, TSS, and phosphorus via infiltration. Provides improved safety features compared to traditional pavements by infiltrating water quickly through the pavement, less pooling of water, and reduced ice formation. Minimizes mosquito breeding by avoiding standing water on site.
  • Economic savings: In addition to water quality and flood control benefits, properly installed permeable pavers can prevent downstream cleanup needs. Permeable pavement can increase property aesthetics that increase property value, particularly when combined with vegetated systems.

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 are given to maximize the GI benefit.

Caution: Permeable pavement SHOULD NOT be used in areas of high traffic volume, with heavy equipment, or with frequent start and stopping
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
permeable pavement sign
Example sign to be placed adjacent to permeable pavements. Source: North Caroline Department of Environmental Quality.
photo for tree trench system, Central Corridor Light rail project
Photo of the completed tree system for the Central Corridor Light Rail Transit project, St. Paul, Minnesota. This system combines permeable pavement with a tree trench system. Image courtesy of the Capitol Region Watershed District.
  • Water quality and water quantity/hydrology: These benefits are combined since permeable pavement design focuses on infiltration, with the subsoil having less impact on pollutant retention compared to other infiltration practices such as bioinfiltration, where organic matter can be incorporated into the design.
    • Ensure the subgrade is flat. Since roads are typically sloped, utilize terracing in the subgrade to achieve flat slopes. See page 5 of the North Carolina design guidance.
    • Incorporate signage into the design to ensure maintenance activities do not affect the infiltration properties of the pavement.
    • Design to maximize retention time and prevent short-circuiting. Storage may be increased by use of geotextile subgrades. An example is presented by Nnadi et al, (2014).
    • Plan for the expected loading on the permeable pavement and ensure capabilities and reduce compaction or clogging
    • Use in conjunction with other treatments to establish a treatment train or reuse water on site
    • Some research has been conducted into use of geotextiles and other amendments for enhancing water quality treatment. See Ostrom and Davis (2019) and Nnadi et al. (2014).
  • Energy:
    • If feasible incorporate energy sources into the design, such as solar arrays and ground source heat pump systems
  • Climate resiliency:
    • Established systems using permeable pavement reduces the runoff impact on surrounding waterways through decreased pollutant loads and increased infiltration
    • Permeable pavement systems can be established to support vegetation through water reuse systems, promoting further enhancement of water
    • Use light colored pavements to reflect incoming solar energy and reduce heat island effects
  • Habitat improvement: Permeable pavement has minimal benefit for habitat but can be combined with vegetated practices. See habitat benefits for bioretention, tree trenches, and swales.
  • Community livability:
    • When appropriate and feasible, incorporate vegetated practices or harvest and reuse systems (see Beechem et al., 2010) into the design to improve aesthetics and provide additional water quality and quantity benefits.
    • Incorporation of vegetation promotes mental health
  • Health benefits:
    • Choose pavements to maximize traction in cold climates
    • Use light colored pavements to reflect incoming solar energy and reduce heat island effects
  • Economic benefits and savings:
    • Reduction in maintenance cost for vegetation if water reuse system is used in conjunction with permeable pavement
    • Integrate vegetation into the landscape design to create habitat, pathways, picnic areas, etc.

Recommended reading

References

This page was last edited on 16 February 2023, at 21:23.