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* geo-grids for sites with heavy vehicle loading
* geo-grids for sites with heavy vehicle loading
* monitoring wells and clean-outs
* monitoring wells and clean-outs
<gallery mode="packed-overlay" perrow=5 widths=150px heights=150px>
File:PICPDouble.png|Permeable Interlocking Concrete Pavers (PICP) on a road with concrete edge restraints separating the impervious and permeable pavements.
File:Gridpaver.png.jpg|Permeable Grid System filled with gravel.
File:PaveDrain.jpg|Permeable Articulated Block Systems: PaveDrain at the LSRCA headquarters in Newmarket, ON is an example of an articulated block system designed for heavy loads.
File:perviousconcrete.png|Pervious Concrete applied to an alleyway in Chicago (Source: City of Chicago).
File:Porousasphalt.png|Porous Asphalt parking lot (Source: Villanova Urban Stormwater Partnership).
</gallery>
==Planning considerations==
==Planning considerations==
===Space===
===Space===
[[File:IMAX permeable pavement.JPG|thumb|Permeable pavement in the IMAX parking lot, Mississauga ON]]
[[File:IMAX permeable pavement.JPG|thumb|500px|Permeable pavement in the IMAX parking lot, Mississauga ON]]
Permeable pavements can be used for the entire parking lot, driveway or road surface, or be designed to to receive runoff from adjacent impervious surfaces. For example, the parking spaces of a parking lot or road can be permeable pavements while the drive lanes are conventional asphalt. The impervious area draining on to the permeable pavement should not exceed the area of the permeable pavement itself. Relatively clean drainage areas such as roofs may be up to 4 times the size of the pavement but should include filtration pretreatment to remove coarse debris prior to being conveyed directly to the storage reservoir.
Permeable pavements can be used for the entire parking lot, driveway or road surface, or be designed to to receive runoff from adjacent impervious surfaces. For example, the parking spaces of a parking lot or road can be permeable pavements while the drive lanes are conventional asphalt. The impervious area draining on to the permeable pavement should not exceed the area of the permeable pavement itself. Relatively clean drainage areas such as roofs may be up to 4 times the size of the pavement but should include filtration pretreatment to remove coarse debris prior to being conveyed directly to the storage reservoir.
Consult the manufacturer for the design specifications of their product. In pervious concrete and porous asphalt systems, the concrete or asphalt mix specifications and construction procedures are key to proper functioning. These systems require well-trained and experienced contractors for installation.
Consult the manufacturer for the design specifications of their product. In pervious concrete and porous asphalt systems, the concrete or asphalt mix specifications and construction procedures are key to proper functioning. These systems require well-trained and experienced contractors for installation.
{{:Permeable paving: Specifications}}
{{:Permeable pavements: Specifications}}
===Foundation Aggregates===
===Foundation Aggregates===
The bottom of the reservoir should be level so that water infiltrates evenly.
The bottom of the reservoir should be level so that water infiltrates evenly.
'''[[Permeable paving: Sizing]]'''
'''[[Permeable pavements: Sizing]]'''
===Geotextile===
===Geotextile===
[[File:PavementwithTrees.png|thumb|400px|Permeable pavers in Hoboken, NJ used around trees which allow air and water to reach the roots (Source: Bruce Ferguson)]]
[[Geotextiles]] are non-woven needle punched, or woven monofilament geotextile fabric that may be placed between the storage reservoir and native soil to maintain separation. Geotextiles are commonly used on low strength soils (CBR <4). Where expansive clays are present, a non-infiltrating design may be necessary. If used, geotextile socks around perforated pipes should conform to ASTM D6707 with minimum water flow rate conforming to ASTM D4491 (12,263 L/min/m2 at 5 cm head).
[[Geotextiles]] are non-woven needle punched, or woven monofilament geotextile fabric that may be placed between the storage reservoir and native soil to maintain separation. Geotextiles are commonly used on low strength soils (CBR <4). Where expansive clays are present, a non-infiltrating design may be necessary. If used, geotextile socks around perforated pipes should conform to ASTM D6707 with minimum water flow rate conforming to ASTM D4491 (12,263 L/min/m2 at 5 cm head).
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>
===Modeling permeable paving in the Treatment Train Tool===
===Modelling permeable pavements in the Treatment Train Tool===
'''[[Permeable paving: TTT]]'''
'''[[Permeable pavements: TTT]]'''
==Construction Considerations==
==Construction Considerations==
*'''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>.
==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 paving: Maintenance|Permeable pavement: 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]]
==Life Cycle Costs==
==Life Cycle Costs==
|style="text-align: center;" |King City, Ontario
|style="text-align: center;" |King City, Ontario
|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;" |'''<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;" |[https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ TRCA (2008b)]
|style="text-align: center;" |[https://sustainabletechnologies.ca/app/uploads/2013/03/PP_FactsheetSept2011-compressed.pdf/ TRCA (2008)]
|-
|-
|rowspan="7" style="text-align: center;" | Permeable pavement with underdrain
|rowspan="7" style="text-align: center;" | Permeable pavement with underdrain
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].
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].
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, 2008b]. 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.
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.
===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 (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===
* ''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)].
*''Improved Street Tree Health:'' Permeable pavements installed around tree planting zones in hardscapes help provide air and water to root systems, thereby contributing to healthier, longer lasting trees that require less manual irrigation.
*''Quiet Streets:'' Porous asphalt surfaces absorb sound energy and dissipate air pressure around tires before any noise is generated. Tire noise is lower in loudness and pitch for a porous surface than a corresponding dense pavement <ref name="example3" />. Segmented pavers do not share this benefit and are generally noisier than asphalt roads.
*''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==
==Proprietary Links==
*[http://nilex.com/products/pavedrain Pavedrain, distributed by Nilex]
*[http://nilex.com/products/pavedrain Pavedrain, distributed by Nilex]
*[http://santerrastonecraft.com/landscape/paving-stones/terra-flo Terra flo, Santerra]
*[http://santerrastonecraft.com/landscape/paving-stones/terra-flo Terra flo, Santerra]
*[https://permacon.ca/en/ Various Products, Permacon]
===Pre-cast pervious===
===Pre-cast pervious===
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/hanpave/ Hanpave]
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/hanpave/ Hanpave]
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/heavy-duty-ground-grid/ HAHN heavy duty ground grid]
*[https://www.hahnplastics.com/ca/products/ground-reinforcement-and-surfaces/heavy-duty-ground-grid/ HAHN heavy duty ground grid]
*[https://permacon.ca/en/ Permacon]
==Gallery==
==Gallery==
{{:Permeable paving: Gallery}}
{{:Permeable pavements: Gallery}}
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