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[[File:PermeablePaving CrossSection.png|border|550px|Permeable Pavement cross sections showing full and partial infiltration designs. Source: GVRD, 2005]]
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[[File:OverflowEdge.png|thumb|Porous asphalt system with overflow edge draining to a reservoir. Source: Pennsylvania Department of Environmental Protection (PDEP). 2006.]]
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*[http://nilex.com/products/pavedrain Pavedrain, distributed by Nilex]
Also see references as direct web page links above.
→References
==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.
[[Permeable pavements|This is a porous surface]]
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:
* Permeable interlocking pavers (concrete and composite materials)
* Permeable interlocking pavers (concrete and composite materials)
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.
==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.
===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===
|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;" |<span class="plainlinks">[https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf TRCA (2008)]</span>
|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;" |'''<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.">45%*</span></u>'''
|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;" |<span class="plainlinks">[https://sustainabletechnologies.ca/app/uploads/2016/02/KPP-Ext_FinalReport_Dec2015.pdf Van Seters and Drake (2015)]</span>
|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:TSS - permeable pavement.JPG|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:TP - permeable pavement.JPG|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 and a total of 296 monitored storm events. 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. 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 447 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 media filter manufactured treatment device as part of the treatment train design. An example of a design variation to improve phosphorus retention is including an 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===
*''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==
==References==