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→Water Quality
==Overview==
==Overview==
Permeable pavements are an alternative to conventional impervious pavement that allows stormwater to drain through the surface and into a stone reservoir, where it infiltrates into the underlying native soil or is temporarily detained. Depending on the native soil properties and physical constraints, the system may be designed with no underdrain for full infiltration, with an underdrain for partial infiltration, or with an impermeable liner and underdrain for a non-infiltrating, or detention and filtration only practice.
Permeable pavements are an alternative to conventional impervious pavement that allows stormwater to drain through the surface and into a stone reservoir, where it infiltrates into the underlying native soil or is temporarily detained. Depending on the native soil properties and physical constraints, the system may be designed with no underdrain for full infiltration, with an underdrain for partial infiltration, or with an impermeable liner and underdrain for a non-infiltrating, or detention and filtration only practice.
Take a look at the downloadable Permeable Pavements Factsheet below for a .pdf overview of this LID Best Management Practice:
{{Clickable button|[[File:P.P Pic.png|150 px|link=https://wiki.sustainabletechnologies.ca/images/7/7e/Permeable_Pavement_Factsheet.pdf]]}}
Permeable pavement types include:
Permeable pavement types include:
{{textbox|Permeable paving is ideal for:
{{textbox|Permeable paving is ideal for:
*Sites with limited space for other surface stormwater BMPs
*Sites with limited space for other surface stormwater BMPs
*Projects such as low traffic roads, parking lots, driveways, pedestrian plazas and walkways}}
*Projects such as low traffic roads, parking lots, driveways, pedestrian plazas and walkways
*Locations where increased skid resistance and melting rate of snow and ice, and decreased demand for de-icing salt application during winter are desireable}}
'''The fundamental components of a permeable paving system are:'''
'''The fundamental components of a permeable paving system are:'''
<gallery mode="packed-hover" perrow=5 widths=150px heights=150px>
<gallery mode="packed-hover" perrow=5 widths=150px heights=150px>
File:Frankenthal - Versickerungsfähige Pflaster.jpg|Permeable Interlocking Concrete Pavers (PICP) on a roadway.
File:Frankenthal - Versickerungsfähige Pflaster.jpg|Permeable Interlocking Concrete Pavers (PICP) on a roadway.
File:Gridpavers.jpg|Permeable Grid System in parking stalls filled with gravel (Source: Alexander Eichler).
File:Gridpaver.png.jpg|Permeable Grid System filled with gravel (Source: Alexander Eichler).
File:ArticulatedBlockPavers.png|Permeable Articulated Block Systems; mostly used for erosion control sites.
File:ArticulatedBlockPavers.png|Permeable Articulated Block Systems; mostly used for erosion control sites.
File:perviousconcrete.png|Pervious Concrete applied to an alleyway in Chicago (Source: City of Chicago).
File:perviousconcrete.png|Pervious Concrete applied to an alleyway in Chicago (Source: City of Chicago).
==Planning considerations==
==Planning considerations==
===Infiltration===
===Infiltration===
For information about constraints to infiltration practices, and approaches and tools for identifying and designing within them see [[Infiltration]].
Systems located in low permeability soils with an infiltration rate of less than 15 mm/hr (i.e., hydraulic conductivity of less than 1x10<sup>-6</sup> cm/s), require incorporation of a perforated pipe underdrain. Pavements require an impermeable geomembrane where the underlying soils are contaminated or the pavement is within two year time-of-travel wellhead protection area (see local drinking water source protection plan)
===Native Soil===
Permeable pavements can be constructed over any soil type, but hydrologic soil group (HSG) A or B soils are best for achieving water balance and erosion control objectives. Facilities should be located on portions of the site with the highest infiltration rates. Native soil infiltration rate at the proposed facility location and depth should be confirmed through in-situ measurements of hydraulic conductivity under field saturated conditions. For guidance on infiltration testing and selecting a design infiltration rate see [[Design infiltration rate]]. Systems located on low permeability soils with an infiltration rate of less than 15 mm/hr (i.e., hydraulic conductivity of less than 1x10<sup>-6</sup> cm/s), should include a perforated pipe [[Underdrain | underdrain]]. A liner will be required if native soils are contaminated.
===Space===
===Space===
Permeable pavements should be located down-gradient from building foundations. If the pavement does not receive drainage from other surfaces, no setback is required. If the pavement receives drainage from other surfaces a minimum setback of four metres down-gradient is recommended. A smaller setback may be permissible where foundations are protected by a geomembrane.
Permeable pavements should be located down-gradient from building foundations. If the pavement does not receive drainage from other surfaces, no setback is required. If the pavement receives drainage from other surfaces a minimum setback of four metres down-gradient is recommended. A smaller setback may be permissible where foundations are protected by a geomembrane.
The use of permeable pavement on highway shoulders has been found to be technically feasible and can be cost-effective when compared to conventional practices.<ref> Weiss, P., Kayhanian, M., Gulliver, J.S., Khazanovich, L. 2019. Permeable pavement in northern North American urban areas: research review and knowledge gaps. International Journal of Pavement Engineering.Vol. 20, No. 2, 143-162. https://www.tandfonline.com/doi/full/10.1080/10298436.2017.127948</ref>
===Site Topography===
===Site Topography===
Permeable pavement surface slope should be at least 1% and no greater than 5%. Steeper slopes may require additional features (see subgrade section below). Pervious areas should not drain onto permeable pavements.
Permeable pavement surface slope should be at least 1% and no greater than 5%. Steeper slopes may require additional features (see subgrade section below). Pervious areas should not drain onto permeable pavements.
===Groundwater===
===Water Table===
Maintaining a separation of one metre between the elevations of the base of the practice and the seasonally high water table, or top of bedrock is recommended. Lesser or greater values may be considered based on groundwater mounding analysis. See [[Groundwater]] page for further guidance and a spreadsheet tool.
Maintaining a separation of one metre between the elevations of the base of the practice and the seasonally high water table, or top of bedrock is recommended. Lesser or greater values may be considered based on groundwater mounding analysis. See [[Groundwater]] page for further guidance and a spreadsheet tool.
===Private Sites===
===Private Sites===
If permeable paving systems are installed on private lots, property owners or managers will need education on their routine maintenance needs, understanding the long-term maintenance plan. They may also be subject to a legally binding maintenance agreement. An incentive program, such as a storm sewer user fee based on the area of impervious cover on a property that is directly connected to a storm sewer, could be used to encourage property owners or managers to maintain existing practices.
If permeable paving systems are installed on private lots, property owners or managers will need education on their routine maintenance needs, understanding the long-term maintenance plan. They may also be subject to a legally binding maintenance agreement. An incentive program, such as a storm sewer user fee based on the area of impervious cover on a property that is directly connected to a storm sewer, could be used to encourage property owners or managers to maintain existing practices.
For a table summarizing information on planning considerations and site constraints see [[Site considerations]].
==Design==
==Design==
[[File:PermeablePaving CrossSection.png|thumb|550px|Permeable Pavement cross-sections showing full and partial infiltration designs (without and with underdrains, respectively). Source: GVRD, 2005]]
===Subgrade===
===Subgrade===
For infiltrating pavements, subgrade slopes should be minimized so that runoff will be able to infiltrate evenly through the entire surface. For steeply sloped sites (>5%), check dams, berms or weir structures on the native soils of the pavement should be considered. If the system is not designed for infiltration, the bottom should be sloped at 1 to 5% toward the underdrain. Subgrades should be compacted to 95% Standard Proctor Density. If a lesser value is desired to promote infiltration, a thicker sub-base should be considered. Subgrade soils should not be scarified.
For infiltrating pavements, subgrade slopes should be minimized so that runoff will be able to infiltrate evenly through the entire surface. For steeply sloped sites (>5%), check dams, berms or weir structures on the native soils of the pavement should be considered. If the system is not designed for infiltration, the bottom should be sloped at 1 to 5% toward the underdrain. Subgrades should be compacted to 95% Standard Proctor Density. If a lesser value is desired to promote infiltration, a thicker sub-base should be considered. Subgrade soils should not be scarified.
===Geotextile===
The use of geotextile fabric between layers within the permeable pavement cross-section can limit infiltration rates due to the collection of solids on the filter fabric that slows infiltration as the pavement ages. While the use of geotextile fabric can improve retention of total suspended solids, the potential for clogging and the cost of rehabilitation typically negate the advantages of geotextile fabric.<ref> Weiss, P., Kayhanian, M., Gulliver, J.S., Khazanovich, L. 2019. Permeable pavement in northern North American urban areas: research review and knowledge gaps. International Journal of Pavement Engineering.Vol. 20, No. 2, 143-162. https://www.tandfonline.com/doi/full/10.1080/10298436.2017.127948</ref>
===Pretreatment===
===Pretreatment===
===Underdrain===
===Underdrain===
The diagram below displays permeable pavement cross sections showing full and partial infiltration designs.<ref>Greater Vancouver Regional District (GVRD). 2005. Stormwater Source Control Design Guidelines 2005. Prepared by Lanarc Consultants Limited, Kerr Wood Leidal Associates Limited and Goya Ngan. </ref> See [[Underdrains]] page for further guidance.
The diagram to the right displays permeable pavement cross sections showing full and partial infiltration designs.<ref>Greater Vancouver Regional District (GVRD). 2005. Stormwater Source Control Design Guidelines 2005. Prepared by Lanarc Consultants Limited, Kerr Wood Leidal Associates Limited and Goya Ngan. </ref> See [[Underdrains]] page for further guidance.
===Access Structures===
===Access Structures===
===Overflow===
===Overflow===
All designs require an overflow outlet connected to a storm sewer with capacity to convey larger storms. This is normally achieved with a catch basin outlet, but water may also be directed to a downstream practice (e.g. bioretention, swale). Another option is a gravel diaphragm or trench along the downgradient edge of the pavement that drains to the storage reservoir below.
All designs require an overflow outlet connected to a storm sewer with capacity to convey larger storms. This is normally achieved with a catch basin outlet, but water may also be directed to a downstream practice (e.g. bioretention, swale). Another option is a gravel diaphragm or trench along the downgradient edge of the pavement that drains to the storage reservoir below.
{{:Permeable pavements: Specifications}}
{{:Permeable pavements: Specifications}}
Further details for specifically permeable interlocking pavers (PICPs) by the American Society of Civil Engineers (ASCE), including: base depths, layering specifications, vehicular load requirements etc. can be found in the following standard - [https://ascelibrary.org/doi/book/10.1061/9780784415009 Permeable Interlocking Concrete Pavement, Standard ASCE/T&DI/ICPI 68-18] as well.
===Foundation Aggregates===
===Foundation Aggregates===
[[File:OverflowEdge.png|thumb|Porous asphalt system with overflow edge draining to a reservoir. Source: Pennsylvania Department of Environmental Protection (PDEP). 2006.]]
All aggregates should meet the following criteria:
All aggregates should meet the following criteria:
* Porosity of 0.4
* Porosity of 0.4
For more information, also see [[Aggregates]] page.
For more information, also see [[Aggregates]] page.
===Sizing Stone Reservoirs===
===Sizing Stone Reservoirs===
Permeable paving is not typically used in locations subject to heavy loads. However, some permeable pavements are designed for heavy loads and have been used in commercial port loading and storage areas. A flexible geogrid structure may be used to improve the structural capacity of the pavement by spreading loads over a larger area. Increasing the base thickness will also improve structural capacity.
Permeable paving is not typically used in locations subject to heavy loads. However, some permeable pavements are designed for heavy loads and have been used in commercial port loading and storage areas. A flexible geogrid structure may be used to improve the structural capacity of the pavement by spreading loads over a larger area. Increasing the base thickness will also improve structural capacity.
<gallery mode="packed" widths=300px heights=300px>
<gallery mode="packed" widths=300px heights=300px>
File:PaveDrain.jpg|PaveDrain at the LSRCA headquarters in Newmarket, ON is an example of an articulated block system designed for heavy loads.
File:Articulatedblocksystem.png|Permeable articulated block system at the LSRCA headquarters in Newmarket, ON is designed for heavy loads.
File:Geogitter-4.jpg|Geogrids like these are sometimes incorporated into the layers of permeable pavement foundation aggregates to provide additional stability and conserve aggregate material.
File:Geogitter-4.jpg|Geogrids like these are sometimes incorporated into the layers of permeable pavement foundation aggregates to provide additional stability and conserve aggregate material.
</gallery>
</gallery>
===Modelling permeable pavements in the Treatment Train Tool===
===Modelling permeable pavements in the Treatment Train Tool===
'''[[Permeable pavements: TTT]]'''
'''[[Permeable pavements: TTT]]'''
==Construction Considerations==
==Construction==
Properly installed permeable pavement requires trained and experienced construction contractors. The following general recommendations apply:
Properly installed permeable pavement requires trained and experienced construction contractors. The following general recommendations apply:
*'''Sediment Control''': The treatment area should be fully protected during construction so that no sediment reaches the permeable pavement system. Construction vehicle traffic should not be permitted on the permeable pavement and its drainage areas once the pavement has been installed.
*'''Sediment Control''': The treatment area should be fully protected during construction so that no sediment reaches the permeable pavement system. Construction vehicle traffic should not be permitted on the permeable pavement and its drainage areas once the pavement has been installed.
*'''Base Construction''': Aggregate should be placed in 100 mm to 150 mm lifts and compacted with a minimum 9 ton steel drum vibratory roller. A light weight deflectometer may be used to test compaction level of open graded stone and compare to specifications.
*'''Base Construction''': Aggregate should be placed in 100 mm to 150 mm lifts and compacted with a minimum 9 ton steel drum vibratory roller. A light weight deflectometer may be used to test compaction level of open graded stone and compare to specifications.
*'''Weather''': Porous asphalt and pervious concrete require a specific temperature range to set properly and the setting time can be several days<ref>City of Portland. 2004. Portland Stormwater Management Manual. Prepared by the Bureau of Environmental Services (BES). Portland, OR.</ref>.
*'''Weather''': Porous asphalt and pervious concrete require a specific temperature range to set properly and the setting time can be several days<ref>City of Portland. 2004. Portland Stormwater Management Manual. Prepared by the Bureau of Environmental Services (BES). Portland, OR.</ref>.
Take a look at the [[Construction]] and [[Finishing grades and surface layer installation: permeable pavements]] page by clicking below for further details about proper construction practices.
<br/>
{{Clickable button|[[File:P.P Pic.png|150px|link=https://wiki.sustainabletechnologies.ca/wiki/Finishing_grades_and_surface_layer_installation:_permeable_pavements]]}}
==Inspection and Maintenance==
==Inspection and Maintenance==
Permeable pavements require regular inspection and maintenance to ensure proper functioning. The limiting factor for permeable pavements is clogging of the surface course or joint filler between pavers. As these start to fill, the trapped sediment becomes finer and finer until they eventually become clogged. Ideally, signs should be posted on the site identifying permeable pavement. This can also serve as a public awareness and education opportunity. See: [[Permeable pavements: Maintenance]]
Permeable pavements require regular inspection and maintenance to ensure proper functioning. The limiting factor for permeable pavements is clogging of the surface course or joint filler between pavers. As these start to fill, the trapped sediment becomes finer and finer until they eventually become clogged. Ideally, signs should be posted on the site identifying permeable pavement. This can also serve as a public awareness and education opportunity. See: [[Permeable pavements: Maintenance]].
<br>
Take a look at the [[Inspection and Maintenance: Permeable Pavement]] page by clicking below for further details about proper inspection and maintenance practices:
{{Clickable button|[[File:Perme pavement banner.JPG|150 px|link=https://wiki.sustainabletechnologies.ca/wiki/Inspection_and_Maintenance:_Permeable_Pavement]]}}
==Life Cycle Costs==
==Life Cycle Costs==
Initial construction costs for permeable pavements are typically higher than conventional asphalt pavement surfaces, largely due to the price of the surface course and thicker aggregate base needed for stormwater storage. However, the cost difference is reduced or eliminated when total life-cycle costs, or the total cost to construct and maintain the pavement over its lifespan, are considered. Other potential savings and benefits include reduced need for storm sewer pipes and other stormwater practices, less developable land consumed for stormwater treatment, and ancillary benefits (improved aesthetics and reduced urban heat island effect). These systems are especially cost effective in existing urban development where parking lot expansion is needed, but there is not sufficient space for other types of BMPs. They combine parking, stormwater infiltration, retention, and detention into one facility. See also: [[Cost analysis resources]]
Initial construction costs for permeable pavements are typically higher than conventional asphalt pavement surfaces, largely due to the price of the surface course and thicker aggregate base needed for stormwater storage. However, the cost difference is reduced or eliminated when total life-cycle costs, or the total cost to construct and maintain the pavement over its lifespan, are considered. Other potential savings and benefits include reduced need for storm sewer pipes and other stormwater practices, less developable land consumed for stormwater treatment, and ancillary benefits (improved aesthetics and reduced urban heat island effect). These systems are especially cost effective in existing urban development where parking lot expansion is needed, but there is not sufficient space for other types of BMPs. They combine parking, stormwater infiltration, retention, and detention into one facility. See also: [[Cost analysis resources]]<br>
To learn about Life Cycle Costs associated with this practice (i.e. Pre-construction, Excavation, Materials & Installation, Project Management, Overhead, Inspection and Maintenance, Rehabilitation and other associated costs), visit the [[Permeable pavements: Life Cycle Costs]] & [[Porous Asphalt: Life Cycle Costs]] pages to view accurate (found to be within ±14% of actual construction costs<ref>Credit Vally Conservation (CVC). 2019. Life-cycle costing tool 2019 update: sensitivity analysis. Credit Valley Conservation, Mississauga, Ontario. https://sustainabletechnologies.ca/app/uploads/2020/04/LCCT-Sensitivity-Analysis_March2020.pdf</ref>) BMP cost estimates for full-, partial- and no-infiltration design variations. Alternatively you can use the [https://sustainabletechnologies.ca/lid-lcct/ STEP's Low Impact Development Life Cycle Costing Tool (LID LCCT)] to generate cost estimates customized to your own LID stormwater design project specifications.
Take a look at the [[Permeable pavements: Life Cycle Costs]] & [[Porous Asphalt: Life Cycle Costs]] pages by clicking the corresponding links below for further details:
{{Clickable button|[[File:Construction Breakdown PP Full Infil.PNG|150 px|link=https://wiki.sustainabletechnologies.ca/wiki/Permeable_pavements:_Life_Cycle_Costs]]}}
{{Clickable button|[[File:Construction Breakdown PA Full Infil.PNG|125 px|link=https://wiki.sustainabletechnologies.ca/wiki/Porous_Asphalt:_Life_Cycle_Costs]]}}<br>
==Performance==
==Performance==
|Partial-based on available storage, native soil infiltration rate and if a flow restrictor is used
|Partial-based on available storage, native soil infiltration rate and if a flow restrictor is used
|-
|-
|'''Permeable Interlocking Pavements'''
|'''Permeable pavement with underdrain and impermeable liner'''
|No-some volume reduction occurs through evaporation
|No-some volume reduction occurs through evaporation
|Yes-size for water quality storage requirement
|Yes-size for water quality storage requirement
Research on the volumetric runoff reduction performance of permeable pavements have been conducted on pavements with and without an underdrain in the base. Volumetric performance improves when:
Research on the volumetric runoff reduction performance of permeable pavements have been conducted on pavements with and without an underdrain in the base. Volumetric performance improves when:
* Native soils have high infiltration capacity.
* Native soils have high infiltration capacity.
* Impervious surface draining onto the permeable pavement is limited or absent.
* Impervious surfaces draining onto the permeable pavement surface is limited or absent.
* Underdrain is elevated above the native soil and/or a flow restrictor is installed on the underdrain.
* Underdrain is elevated above the native soil and/or a flow restrictor is installed on the underdrain or outlet storm sewer pipe.
All permeable pavements have very high surface infiltration rates when appropriately maintained. Therefore, the surface course type (i.e. PICP, pervious concrete) is not a key factor in determining volumetric runoff reduction performance.
All permeable pavements have very high surface infiltration rates when appropriately constructed and maintained. Therefore, the surface course type (e.g. permeable interlocking concrete pavers, pervious concrete, porous asphalt, etc.) is not a key factor in determining volumetric runoff reduction performance.
{|class="wikitable"
{|class="wikitable"
!'''LID Practice'''
!'''LID Practice'''
!'''Location'''
!'''Location'''
!'''<u><span title="Note: Runoff reduction estimates are based on differences between runoff volume from the practice and total precipitation over the period of monitoring unless otherwise stated." >Runoff Reduction*</span></u>'''
!'''<span title="Note: Runoff reduction estimates are based on differences between runoff volume from the practice and total precipitation over the period of monitoring unless otherwise stated." >Runoff Reduction*</span>'''
!'''Reference'''
!'''Reference'''
|-
|-
|rowspan="6" style="text-align: center;" | Permeable pavement without underdrain
|rowspan="7" style="text-align: center;" | Permeable pavement without underdrain
|style="text-align: center;" |Guelph, Ontario
|-
|style="text-align: center;" |90%
|style="text-align: center;" |King City, Ontario
|style="text-align: center;" |James (2002)<ref>James, W. 2002. Green Roads: Research into Permeable Pavers. Stormwater.
|style="text-align: center;" |'''<span title="Note: In this study, there was no underdrain in the pavement base, but an underdrain was located 1 m below the native soils to allow for sampling of infiltrated water. Temporary water storage fluctuations in the base were similar to those expected in a no underdrain design." >99%*</span>'''
|style="text-align: center;" |<span class="plainlinks">[https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf TRCA (2008)]</span><ref>TRCA. 2008. Permeable Pavement and Bioretention Swale Demonstration Project. Seneca College, King City, Ontario. https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf</ref>
|-
|-
|style="text-align: center;" |Pennsylvania
|style="text-align: center;" |Pennsylvania
|style="text-align: center;" |Kwiatkowski et al. (2007)<ref name="example1">Kwiatkowski, M., Welker, A.L., Traver, R.G., Vanacore, M., Ladd. T. 2007. Evaluation of an infiltration best management practice utilizing pervious concrete. Journal of the American Water Resources Association. Vol. 43. No. 5. pp. 1208-1222.</ref>
|style="text-align: center;" |Kwiatkowski et al. (2007)<ref name="example1">Kwiatkowski, M., Welker, A.L., Traver, R.G., Vanacore, M., Ladd. T. 2007. Evaluation of an infiltration best management practice utilizing pervious concrete. Journal of the American Water Resources Association. Vol. 43. No. 5. pp. 1208-1222.</ref>
|-
|-
|style="text-align: center;" |France
|style="text-align: center;" |Connecticut
|style="text-align: center;" |97%
|style="text-align: center;" |'''<span title="Note: Runoff reduction estimates are based on differences in runoff volume between the practice and a conventional impervious surface over the period of monitoring." >72%*</span>'''
|style="text-align: center;" |Legret and Colandini (1999)<ref>Legret, M and V. Colandani. 1999. Effects of a porous pavement structure with a reservoir structure on runoff water: water quality and fate of metals. Water Science and Technology. 39(2): 111-117</ref>
|style="text-align: center;" |Gilbert and Clausen (2006)<ref>Gilbert, J. and J. Clausen. 2006. Stormwater runoff quality and quantity from asphalt,
paver and crushed stone driveways in Connecticut. Water Research 40: 826-832.</ref>
|-
|-
|style="text-align: center;" |Washington
|style="text-align: center;" |Washington
performance of permeable pavement systems. Water Research 37(18): 4369-4376 </ref>
performance of permeable pavement systems. Water Research 37(18): 4369-4376 </ref>
|-
|-
|style="text-align: center;" |Connecticut
|style="text-align: center;" |Guelph, Ontario
|style="text-align: center;" |'''<u><span title="Note: Runoff reduction estimates are based on differences in runoff volume between the practice and a conventional impervious surface over the period of monitoring." >72%*</span></u>'''
|style="text-align: center;" |90%
|style="text-align: center;" |Gilbert and Clausen (2006)<ref>Gilbert, J. and J. Clausen. 2006. Stormwater runoff quality and quantity from asphalt,
|style="text-align: center;" |James (2002)<ref>James, W. 2002. Green Roads: Research into Permeable Pavers. Stormwater.
March/April.</ref>
|-
|style="text-align: center;" |France
|style="text-align: center;" |97%
|style="text-align: center;" |Legret and Colandini (1999)<ref>Legret, M and V. Colandani. 1999. Effects of a porous pavement structure with a reservoir structure on runoff water: water quality and fate of metals. Water Science and Technology. 39(2): 111-117</ref>
|-
|rowspan="10" style="text-align: center;" | Permeable pavement with underdrain
|-
|style="text-align: center;" |Montreal
|style="text-align: center;" |26 to 98%
|style="text-align: center;" |Vaillancourt ''et al.'' (2019) <ref>Vaillancourt, C., Duchesne, S., & Pelletier, G. 2019. Hydrologic performance of permeable pavement as an adaptive measure in urban areas: case studies near Montreal, Canada. Journal of Hydrologic Engineering, 24(8), 05019020.</ref>
|-
|style="text-align: center;" |Mississauga
|style="text-align: center;" |61 to 99%
|style="text-align: center;" |<span class="plainlinks">[https://cvc.ca/wp-content/uploads/2018/05/IMAX-Low-Impact-Development-Monitoring-Case-Study-may-24.pdf CVC (2018)]</span><ref>CVC. 2018. Case Study: Monitoring Low Impact Development at the IMAX demonstration site. February, 2018. https://cvc.ca/wp-content/uploads/2018/05/IMAX-Low-Impact-Development-Monitoring-Case-Study-may-24.pdf</ref>
|-
|-
|style="text-align: center;" |King City, Ontario
|style="text-align: center;" |Seoul, Korea
|style="text-align: center;" |'''<u><span title="Note: In this study, there was no underdrain in the pavement base, but an underdrain was located 1 m below the native soils to allow for sampling of infiltrated water. Temporary water storage fluctuations in the base were similar to those expected in a no underdrain design." >99%*</span></u>'''
|style="text-align: center;" |30 to 65%
|style="text-align: center;" |[https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ TRCA (2008)]
|style="text-align: center;" |Shafique ''et al.'' (2018) <ref>Shafique, M., Kim, R. and Kyung-Ho, K., 2018. Rainfall runoff mitigation by retrofitted permeable pavement in an urban area. Sustainability, 10(4), p.1231.</ref>
|-
|-
|rowspan="7" style="text-align: center;" | Permeable pavement with underdrain
|style="text-align: center;" |Northern Ohio
|style="text-align: center;" |16 to 99%
|style="text-align: center;" |Winston ''et al.'' (2015) <ref>Winston, R. J., Dorsey, J. D., & Hunt, W. F. (2015). Monitoring the performance of bioretention and permeable pavement stormwater controls in Northern Ohio: hydrology, water quality, and maintenance needs. Chagrin River Watershed Partners. Inc. under NOAA award No. NA09NOS4190153.</ref>
|-
|-
|style="text-align: center;" |Vaughan, Ontario
|style="text-align: center;" |Vaughan, Ontario
|style="text-align: center;" |45%<sup>2</sup>
|style="text-align: center;" |'''<span title="Note: Runoff reduction estimates are based on differences in runoff volume between the practice and a conventional impervious surface over the period of monitoring.">45%*</span>'''
|style="text-align: center;" |[https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf/ Van Seters and Drake (2015)]
|style="text-align: center;" |<span class="plainlinks">[https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf Van Seters and Drake (2015)]</span><ref>Van Seters, T. and Drake, J. 2015. Five Year Performance Evaluation of Permeable Pavements. Kortright, Vaughan - Final Draft. December 2015. © Toronto and Region Conservation Authority. https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf</ref>
|-
|-
|style="text-align: center;" |North Carolina
|style="text-align: center;" |North Carolina
|style="text-align: center;" |45% to 60%
|style="text-align: center;" |45% to 60%
|style="text-align: center;" |Schueler ''et al.'' (1987)<ref>Schueler, T. 1987. Controlling urban runoff: a practical manual for planning and designing urban BMPs. Metropolitan Washington Council of Governments. Washington, DC. </ref>
|style="text-align: center;" |Schueler ''et al.'' (1987)<ref>Schueler, T. 1987. Controlling urban runoff: a practical manual for planning and designing urban BMPs. Metropolitan Washington Council of Governments. Washington, DC. </ref>
|-
|-
| colspan="2" style="text-align: center;" |'''<u><span title="Note: This estimate is provided only for the purpose of initial screening of LID practices suitable for achieving stormwater management objectives and targets. Performance of individual facilities will vary depending on site specific contexts and facility design parameters and should be estimated as part of the design process and submitted with other documentation for review by the approval authority." >Runoff Reduction Estimate*</span></u>'''
| colspan="2" style="text-align: center;" |'''<u><span title="Note: This estimate is provided only for the purpose of initial screening of LID practices suitable for achieving stormwater management objectives and targets. Performance of individual facilities will vary depending on site specific contexts and facility design parameters and should be estimated as part of the design process and submitted with other documentation for review by the approval authority." >Runoff Reduction Estimate*</span></u>'''
|-
|-
|}
|}
In a numerical modelling study comparing the predicted hydrologic performance of permeable interlocking concrete pavers without underdrains in New York and Hong Kong, Liu et al. (2017) found pavements performed significantly better in a relatively drier climate (e.g., New York), reducing nearly 90% of runoff volume compared to 70% in a relatively wetter climate (e.g., Hong Kong) and that runoff volume was found to be mostly governed by rainfall intensity.<ref> Liu, C.Y., Chui, T.F.M. 2017. Factors Influencing Stormwater Mitigation in Permeable Pavement. Water. 9, 988. https://www.mdpi.com/2073-4441/9/12/988</ref>
In Canadian and Swedish field studies, vacuum cleaning could only partially restore the surface infiltration capacity of permeable interlocking concrete pavers (PICP) with large spatial variability in the observed infiltration rates post cleaning.<ref> Drake, J., Bradford, A. 2013. Assessing the Potential for Restoration of Surface Permeability for Permeable Pavements Through Maintenance. Water Science and Technology. 2013, 68, 1950-1958. https://pubmed.ncbi.nlm.nih.gov/24225094/ </ref> <ref>Al-Rubaei, A.M., Stenglein, A.L., Viklander, M., Blecken, G.T. 2013. Long-Term Hydraulic Performance of Porous Asphalt Pavements in Northern Sweden. Journal of Irrigation and Drainage Engineering. 39 (6) June 2013. https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IR.1943-4774.0000569 </ref> Potential options for rehabilitating clogged permeable pavements identified to date include combining pressure washing with pure vacuum sweeping to help dislodge sediment accumulated within joints of PICP and porous asphalt <ref> Seghal, K.S., Drake, J., Van Seters, T., Vander Linden, W.K. 2018. Improving Restorative Maintenance Practices for Mature Permeable Interlocking Concrete Pavements. Water. 10 (11), 1588. https://www.mdpi.com/2073-4441/10/11/1588 </ref> <ref> Winston, R.J., Al-Rubaei, A.M., Blecken, G.T., Viklander, M., Hunt, W.F. 2016. Maintenance measures for preservation and recovery of permeable pavement surface infiltration rate – The effects of street sweeping, vacuum cleaning, high pressure washing and milling. Journal of Environmental Management. 169(2016):132-144. https://www.sciencedirect.com/science/article/pii/S0301479715304412c </ref> <ref> Al-Rubaei, A.M., et al., 2013. Long-term hydraulic performance of porous asphalt pavements in Northern Sweden. Journal of Irrigation and Drainage Engineering, 139 (6), 499–505. https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IR.1943-4774.0000569 </ref>, and in pores of pervious concrete<ref> Chopra, M., et al., 2010. Effect of Rejuvenation Methods on the Infiltration Rates of Pervious Concrete Pavements. Journal of Hydrologic Engineering, 15 (6), 426–433. https://pennstate.pure.elsevier.com/en/publications/effect-of-rejuvenation-methods-on-the-infiltration-rates-of-pervi </ref>. Drainage performance evaluations of aged pervious concrete have shown its permeability does not decline as rapidly with age as PICP, but that vacuum cleaning techniques tested to date provide variable or insignificant restorative effect<ref> Drake, J., Bradford, A. 2013. Assessing the Potential for Restoration of Surface Permeability for Permeable Pavements Through Maintenance. Water Science and Technology. 2013, 68, 1950-1958. https://pubmed.ncbi.nlm.nih.gov/24225094/ </ref> <ref>Sustainable Technologies Evaluation Program (STEP). 2019. Permeable Pavements Maintenance. Technical Brief. October 2019. https://sustainabletechnologies.ca/app/uploads/2019/10/PDF-PP-maintenance-tech-brief_Oct2019.pdf </ref>
===Water Quality===
===Water Quality===
Like other stormwater practices, the water quality performance of permeable pavements is closely tied to the reduction of runoff volumes through infiltration, However, permeable pavements are also very effective stormwater runoff filters. Most sediments and associated contaminants are trapped within the surface pores or gravel filled joints between the pavers. A five year study of three permeable pavement surfaces in Vaughan showed total suspended solids (TSS) concentration reductions between 88 and 89% [https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf/ (Van Seters and Drake, 2015)]. Other STEP studies in the Greater Toronto Area have displayed similar results, with only 7% of 181 permeable pavement effluent samples having TSS concentrations above 30 mg/L (median = 7 mg/L)[https://sustainabletechnologies.ca/app/uploads/2015/06/SynthesisWaterQuality_Statistics_May2015.pdf/ TRCA, 2015].
[[File:Permeable_pavement_TSS.png|200px|thumb]]
Like other stormwater practices, the water quality performance of permeable pavements is closely tied to the reduction of runoff volumes through infiltration. However, permeable pavements are also very effective stormwater runoff filters. Most sediments and associated contaminants are trapped within the surface pores or gravel filled joints between the pavers. A five year study of three permeable pavement surfaces in Vaughan showed total suspended solids (TSS) concentration reductions between 88 and 89% [https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf/ (Van Seters and Drake, 2015)]. Other STEP studies in the Greater Toronto Area have displayed similar results, with only 7% of 181 permeable pavement effluent samples having TSS concentrations above 30 mg/L (median = 7 mg/L)[https://sustainabletechnologies.ca/app/uploads/2015/06/SynthesisWaterQuality_Statistics_May2015.pdf/ TRCA, 2015].<br>
Another group of studies of permeable pavements examines the quality of water infiltrated through soils beneath the installations. In these studies the quality of infiltrated water is used as a measure of the potential for contamination of groundwater. One such study of a permeable interlocking concrete pavement installed in a college parking lot in King City, Ontario, showed that stormwater infiltrated through a 60 cm granular reservoir and 1 metre of native soil had significantly lower concentrations of several typical parking lot contaminants relative to runoff from an adjacent asphalt surface [https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ (TRCA, 2008)]. These results are consistent with research on the quality of infiltrated water from permeable pavements in Washington<ref name="example2" /> and Pennsylvannia<ref name="example1" />. As with all stormwater infiltration practices, risk of groundwater contamination from infiltration of runoff laden with road de-icing salt constituents (typically sodium and chloride) may be a concern in lands designated as source protection areas. Chloride ions are extremely mobile in the soil and are readily transported by percolating water to aquifers.
<br>
[[File:Permeable_pavement_TP.png|200px|thumb]]
The two box plot figures to the right show combined stormwater effluent quality results from STEP monitoring projects conducted over a 12-year time period (between 2005 and 2017) at sites within Greater Toronto Area (GTA) municipalities. Total Suspended Solid (TSS) effluent concentration results for permeable pavement practices represent the combined results from 4 sites in the GTA. Median TSS concentration was found to be 8.95 mg/L and exceeded the Canadian Water Quality Guideline of 30 mg/L (CCME, 2002<ref>Canadian Council of Ministers of the Environment (CCME). 2002. Canadian water quality guidelines for the protection of aquatic life: Total particulate matter. In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment, Winnipeg</ref>) during only 12% of the 296 monitored storm events, similar to STEP [[Bioretention#Water_Quality| Bioretention performance]] results. In comparison, median TSS effluent concentration for permeable pavements in the International Stormwater BMP Database was found to be 22.0 mg/L, based on 402 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, which is below the Canadian Water Quality Guideline, but considerably higher than results from STEP studies. Median TP concentration was found to be 0.04 mg/L and exceeded the Ontario Provincial Water Quality Objective (PWQO) of 0.03 mg/L (OMOEE, 1994<ref>Ontario Ministry of Environment and Energy (OMOEE), 1994. Policies, Guidelines and Provincial Water Quality Objectives of the Ministry of Environment and Energy. Queen’s Printer for Ontario. Toronto, ON.</ref>) during 62% of the 300 monitored storm events. In comparison, median TP effluent concentration for permeable pavements in the International Stormwater BMP Database was found to be 0.100 mg/L, based on 365 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, which is also above the Ontario PWQO of 0.03 mg/L. These results indicate that the design of permeable pavements draining to phosphorus-limited receiving waterbodies should include practices or design variations to improve [[Phosphorus]] retention. This could involve including a sorption media filter manufactured treatment device as part of the treatment train design. Another example of a design variation to improve phosphorus retention is including an [[Additives| additive]] to the permeable pavement base aggregate layer to improve phosphorus retention (Ostrom and Davis, 2019)<ref>Ostrom, T.K. and Davis, A.P. 2019. Evaluation of an enhanced treatment media and permeable pavement base to remove stormwater nitrogen, phosphorus, and metals under simulated rainfall. Water research, 166, p.115071.</ref>.<br>
<br>
Another group of studies of permeable pavements examines the quality of water infiltrated through soils beneath the installations. In these studies the quality of infiltrated water is used as a measure of the potential for contamination of groundwater. One such study of a permeable interlocking concrete pavement installed in a college parking lot in King City, Ontario, showed that stormwater infiltrated through a 60 cm granular reservoir and 1 metre of native soil had significantly lower concentrations of several typical parking lot contaminants relative to runoff from an adjacent asphalt surface [https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ (TRCA, 2008)]. These results are consistent with research on the quality of infiltrated water from permeable pavements in Washington<ref name="example2" /> and Pennsylvannia<ref name="example1" />. As with all stormwater infiltration practices, risk of groundwater contamination from infiltration of runoff laden with road de-icing salt constituents (typically sodium and chloride) may be a concern in vulnerable areas for [[Source Water Protection]]. Chloride ions are extremely mobile in the soil and are readily transported by percolating water to aquifers.
===Stream Channel Erosion===
===Stream Channel Erosion===
Permeable pavements help address stream erosion and flood flows by attenuating peak flows through temporary storage and release. A STEP study in Vaughan showed a 91% peak flow reduction due in part to flow restriction on the underdrain [https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf/ (Van Seters and Drake, 2015)]. A later study of three permeable pavements in a parking lot in Mississauga showed peak flow reductions between 39 and 84% for events greater than 25 mm [https://cvc.ca/wp-content/uploads/2018/05/IMAX-Low-Impact-Development-Monitoring-Case-Study-may-24.pdf/ (CVC, 2018)].
Permeable pavements help address stream erosion and flood flows by attenuating peak flows through temporary storage and release. A STEP study in Vaughan showed a 91% peak flow reduction due in part to flow restriction on the underdrain [https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf/ (Van Seters and Drake, 2015)]. A later study of three permeable pavements in a parking lot in Mississauga showed peak flow reductions between 39 and 84% for events greater than 25 mm [https://cvc.ca/wp-content/uploads/2018/05/IMAX-Low-Impact-Development-Monitoring-Case-Study-may-24.pdf/ (CVC, 2018)].
===Other Benefits===
===Other Benefits===
[[File:Renovated Bartholdi Park (37898409602).jpg|thumb|400px|Permeable pavements (left) in Bartholdi Park, DC provides air and water to root systems contributing to healthier, longer lasting trees (Source: USCapitol)]]
* ''Winter Performance:'' Snow plow and deicing costs are reduced due to rapid drainage of snow melt. Puddling on parking lots is also reduced. A two year study of PICP in Vaughan found that the PICP provides equivalent or higher levels of safety compared with asphalt when treated with de-icing products at medium (0.049 kg/m2) or low (0.024 kg/m2) salt application rates<ref>Marvin, J., Scott, J., Van Seters, T., Bowers, B., Drake, J. Winter Maintenance of Permeable Interlocking Concrete Pavement: Evaluating Opportunities to Reduce Road Salt Pollution and Improve Winter Safety, submitted to Transportation Research Record May 2020, under review</ref>.
* ''Winter Performance:'' Snow plow and deicing costs are reduced due to rapid drainage of snow melt. Puddling on parking lots is also reduced. A two year study of PICP in Vaughan found that the PICP provides equivalent or higher levels of safety compared with asphalt when treated with de-icing products at medium (0.049 kg/m2) or low (0.024 kg/m2) salt application rates<ref>Marvin, J., Scott, J., Van Seters, T., Bowers, B., Drake, J. Winter Maintenance of Permeable Interlocking Concrete Pavement: Evaluating Opportunities to Reduce Road Salt Pollution and Improve Winter Safety, submitted to Transportation Research Record May 2020, under review</ref>.
*''Urban Heat Island Effect Reduction:'' Porous materials have less thermal conductivity and thermal capacity than traditional impervious pavement, thereby reducing the urban heat island effect <ref name="example3">Ferguson, B.K. 2005. Porous Pavements. Integrative Studies in Water Management and Land Development. Taylor and Francis: New York.</ref>. Year round measurements of asphalt and PICP surface temperatures in King City, Ontario showed asphalt temperatures above 20°C approximately 12% more often than the adjacent permeable pavers [https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ (TRCA, 2008)].
*''Urban Heat Island Effect Reduction:'' Porous materials have less thermal conductivity and thermal capacity than traditional impervious pavement, thereby reducing the urban heat island effect <ref name="example3">Ferguson, B.K. 2005. Porous Pavements. Integrative Studies in Water Management and Land Development. Taylor and Francis: New York.</ref>. Year round measurements of asphalt and PICP surface temperatures in King City, Ontario showed asphalt temperatures above 20°C approximately 12% more often than the adjacent permeable pavers [https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ (TRCA, 2008)].
*''LEED Credits:'' Permeable pavement has the potential for earning Canadian Green Building Council LEED sustainable sites credits for reducing stormwater pollution and runoff, urban heat island mitigation, and conservation of materials and resources.
*''LEED Credits:'' Permeable pavement has the potential for earning Canadian Green Building Council LEED sustainable sites credits for reducing stormwater pollution and runoff, urban heat island mitigation, and conservation of materials and resources.
==Proprietary Links==
==External links==
{{:Disclaimer}}
{{:Disclaimer}}
===Pre-cast with joints===
===Pre-cast with joints===
*[https://unilock.com/products/driveways/eco-optiloc/?region=1 Eco-Optioc, Unilock]
*[https://www.pavedrain.com/ Pavedrain]
*[https://oakspavers.com/products/enviro-pavers Enviro Pavers, Oaks]
*[https://permacon.ca/en/landscaping/permeable-en/ Permacon]
*[https://santerrastonecraft.com/landscape/paving-stones/terra-flo Santerra, Terra-flow]
*[http://santerrastonecraft.com/landscape/paving-stones/terra-flo Terra flo, Santerra]
*[https://unilock.com/ Unilock]
*[https://permacon.ca/en/ Various Products, Permacon]
===Pre-cast pervious===
===Pre-cast pervious===
*[http://hydropavers.ca/ Hydropavers pervious pavers]
*[http://hydropavers.ca/ Hydropaver]
*[http://www.storm-crete.com/ Stormcrete pervious pavers]
*[http://www.storm-crete.com/ Stormcrete]
===Cast in place===
===Cast-in-place===
*[http://www.lafarge-na.com/wps/portal/na/en/HydromediaDetailWCM_GLOBAL_CONTEXT=/wps/wcm/connectlib_na/Site_na/AllProductDataSheet_Concrete/ProductDatasheet_Concrete_1321037540751/Product_EN Hydromedia]
*[https://www.lafarge.ca/en/hydromedia#:~:text=Hydromedia%E2%84%A2%20is%20a%20fast,ground%20below%20where%20it%20belongs. Hydromedia]
*[https://www.purepave.com/ PurePave]
*[https://www.purepave.com/ PurePave]
===Plastic grid===
===Plastic grid===
*[https://www.ecorastergrid.com/ Ecoraster]
*[https://www.ecorastergrid.com/ Ecoraster]
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/hanpave/ Hanpave]
*[https://www.hahnplastics.com/Hanpave/808000.INT0100 HANH Hanpave]
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/heavy-duty-ground-grid/ HAHN heavy duty ground grid]
*[https://www.hahnplastics.com/Heavy-duty-ground-grid/GH084060 HAHN Heavy duty ground grid]
*[https://permacon.ca/en/ Permacon]
*[https://permacon.ca/en/ Permacon]
==Gallery==
==Gallery==
{{:Permeable pavements: Gallery}}
{{:Permeable pavements: Gallery}}
==References==
Also see references as direct web page links above.
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[[Category:Infiltration]]
[[Category: Green infrastructure]]