Permeable paving

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Conceptual diagram illustrating an adjustable storage underdrainA perforated pipe used to assist the draining of soils. configuration beneath permeable interlocking pavers

Overview

Permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. allows stormwater to drain through the surface and into a stone reservoirAn underlying aggregate material bed that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe., where it infiltrates into the underlying native soilThe natural ground material characteristic of or existing by virtue of geographic origin. or is temporarily detained.

The following are different types of permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil.:

  • Permeable interlocking concrete pavers (PICP)
  • Plastic or concrete grid systems
  • Pervious concrete
  • Pervious asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces.

Permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. is ideal for:

  • Sites with limited space for other surface stormwater BMPsThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.
  • Projects such as low traffic roads, parking lots, driveways, pedestrian plazas and walkways

The fundamental components of a permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. system are:

  • interlocking blocks with infiltration spaces between
  • Precast pervious slabs or pavers
  • a cast in place surface without finesSoil particles with a diameter less than 0.050 mm., so that the finish is pervious to water
  • a bedding course to stabilize the surface
  • underground storage layer of aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

Additional components may include:

Planning considerations

Permeable pavements are surfaces that encourage infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.. They can be used in place of conventional asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. or concrete pavement. These alternatives contain pores, spaces and joints for allowing stormwater to pass through to a stone base, where it infiltrates into underlying native soils or is temporarily detained. Types of permeable pavementAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. include:

  • Pervious concrete
  • Porous asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces.
  • Permeable interlocking concrete pavers (PICP, or just permeable pavers)

Geometry and Site Layout

Permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. can be used for entire parking lot areas or driveways and can be designed to receive runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from adjacent imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces. For example, the parking spaces in a parking lot may be permeable pavers while the drive lanes themselves are imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces.. In general, the imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. area should not exceed 1.2 times the area of the permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. which receives the runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.. A hybrid permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil./infiltration chamber design can feature connection of a roof downspout directly to the stone reservoirAn underlying aggregate material bed that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe. of the permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. system, which is sized to store runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from both the pavement surface and the roof drainage areaThe total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds..

PretreatmentInitial capturing and removal of unwanted contaminants, such as debris, sediment, leaves and pollutants, from stormwater before reaching a best management practice; Examples include, settling forebays, vegetated filter strips and gravel diaphragms.

In most designs, the surface acts as pretreatmentInitial capturing and removal of unwanted contaminants, such as debris, sediment, leaves and pollutants, from stormwater before reaching a best management practice; Examples include, settling forebays, vegetated filter strips and gravel diaphragms. to the stone reservoirAn underlying aggregate material bed that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe. below. Periodic vacuum sweeping and preventative measures like not storing snow or other materials on the pavement are critical to prevent clogging. Another pretreatmentInitial capturing and removal of unwanted contaminants, such as debris, sediment, leaves and pollutants, from stormwater before reaching a best management practice; Examples include, settling forebays, vegetated filter strips and gravel diaphragms. element is to have a choking layer above the coarse gravel storage reservoir.

Landscaping

Landscaped areas must drain away from permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. to prevent sedimentsSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. from running onto the surface. Urban trees will benefit from being surrounded by permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. rather than imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. cover, because their roots receive more air and water. Interlocking pavers used around the base of a tree may be removed as the tree grows.

Risk of Groundwater Contamination

  • Stormwater infiltration practices should not receive runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from high traffic areas where large amounts of de-icing salts are applied (e.g., busy highways), nor from pollution hot spots (e.g., source areas where land uses or activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. such as vehicle fuelling, servicing or demolition areas, outdoor storage or handling areas for hazardous materials and some heavy industry sites)
  • Prioritize infiltration of runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from source areas that are comparatively less contaminated such as roofs, low traffic roads and parking areas
  • Apply sedimentationDeposition of material of varying size, both mineral and organic away from its site of origin by the action of water, wind, gravity or ice.Settling-out or deposition of particulate matter suspended in runoff. pretreatmentInitial capturing and removal of unwanted contaminants, such as debris, sediment, leaves and pollutants, from stormwater before reaching a best management practice; Examples include, settling forebays, vegetated filter strips and gravel diaphragms. practices (e.g., oil and grit separators) before infiltration of road or parking area runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.

Heavy Vehicle Traffic

Permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. is not typically used in locations subject to heavy loads. However, some permeable pavers are designed for heavy loads and have been used in commercial port loadingThe total mass of a pollutant entering a waterbody over a defined time period.The net amount of something (e.g. chemical, such as phosphorus), calculated as the product of concentration and volume in a given time. Some BMPs significantly reduce loading of pollutants to the environment by reducing volume more so than concentration. and storage areas.

Setbacks from Buildings

Permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. should be located downslope from building foundations. If the paving does not receive runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from other surfaces, no setback is required from building foundations. Otherwise, a minimum setback of 4 m down-gradient from building foundations is recommended.

On Private PropertyLand owned by private individuals or companies.

If permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. 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 imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. 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.

Design

Modeling permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. in the Treatment Train Tool

Permeable paving: TTT

Sizing stone reservoirs

The stone reservoirAn underlying aggregate material bed that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe. must meet both runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. storage and structural support requirements. The bottom of the reservoir should be level so that water infiltrates evenly. If the system is not designed for infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface., the bottom should slope at 1 - 5% toward the underdrainA perforated pipe used to assist the draining of soils..

Permeable paving: Sizing

Gallery

Materials

Consult the manufacturer for the design specifications of their product. In pervious concrete and porous asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. systems, the concrete or asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. mix specifications and construction procedures are key to proper functioning. These systems require well-trained and experienced contractors for installation.
Specifications

AggregatesA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

medium sized granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices., free from finesSoil particles with a diameter less than 0.050 mm.

In bioretention systems a choking layer of ≥ 100 mm is the recommended method to prevent migration of finer filter media into an underlying reservoir of coarse aggregate. These same mid sized granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. materials are recommended for use in Stormwater planter underdrains.

Suitable materials include:

High performance bedding (HPB)
Clean, angular aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. screened to between 6 - 10 mm. Widely available and designed specifically for drainage applications. Free from finesSoil particles with a diameter less than 0.050 mm. by definition.
HL 6
Is a clean, angular aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. screened between 10 - 20 mm. Free from finesSoil particles with a diameter less than 0.050 mm. by definition.
Pea Gravel
Rounded natural aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations., screened between 5 - 15 mm, and washed free from finesSoil particles with a diameter less than 0.050 mm..
In most scenarios, a geotextile layer is unnecessary and have been associated with rapid decline and clogging in some circumstances.
Note the uniform size and angularity of this clear stone sample. Note also that the fragments all appear to have a film of fine particles adhering; this material would be improved by being washed prior to use.

This article gives recommendations for aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. to be used to store water for infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.. This is usually called 'Clear stone' at aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. yards. To see an analysis of Ontario Standard Specifications for granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. materials, see OPS Aggregates. For advice on decorative surface aggregatesA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. see Stone

Gravel used for underdrains in bioretention, infiltration trenches and chambers, and exfiltration trenches should be 20 OR 50 mm, uniformly-graded, clean (maximum wash loss of 0.5%), crushed angular stone that has a void ratio of 0.4[1].

The clean wash to prevent rapid accumulation of finesSoil particles with a diameter less than 0.050 mm. from the aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. particles in the base of the reservoir. The uniform grading and the angularity are important to maintain pore throats and clear voids between particles. (i.e. achieve the void ratio). Porosity and permeability are directly influenced by the size, gradation and angularity of the particles [2]. See jar test for on-site verification testing protocols.

Gravel with structural requirements should also meet the following criteria:

  • Minimum durability index of 35
  • Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions

Standard specifications for the gradation of aggregatesA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. are maintained by ASTM D2940


GeotextileFilter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils.

The properties of geotextiles vary widely.

Geotextiles can be used to prevent downward migration of smaller particles in to larger aggregatesA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations., and slump of heavier particles into finer underlying courses. The formation of biofilm on geotextiles has also been shown to improve water quality:

  • By degrading petroleum hydrocarbons[3]
  • By reducing organic pollutant and nutrient concentrations [4]
  • When installing geotextiles an overlap of 150 - 300 mm should be used.

Material specifications should conform to OPSS 1860 for Class II geotextileFilter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils. fabrics [5].

  • Fabrics should be woven monofilament or non-woven needle punched.
  • Woven slit film and non-woven heat bonded fabrics should not be used, as they are prone to clogging.

In choosing a product, consider:

  1. The maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?),
  2. The load bearing ratio of the underlying native soilThe natural ground material characteristic of or existing by virtue of geographic origin. (i.e. is the geotextileFilter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils. needed to prevent downward migration of aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. into the native soilThe natural ground material characteristic of or existing by virtue of geographic origin.?),
  3. The texture (i.e., grain size distribution) of the overlying and underlying materials, and
  4. The suitable apparent opening size (AOS) for non-woven fabrics, or percent open area (POA) for woven fabrics, to maintain water flow even with sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. and microbial film build-up.
Recommended criteria for selection of geotextileFilter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils. fabric
Percent soil/filter mediaThe engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles. passing 0.075 mm (#200 sieve) Non-woven fabric apparent opening size (AOS, mm) Woven fabric percent open area (POA, %) Permittivity (sec-1)
>85 ≤ 0.3 - 0.1
50 - 85 ≤ 0.3 ≥ 4 0.1
15 - 50 ≤ 0.6 ≥ 4 0.2
5 - 15 ≤ 0.6 ≥ 4 0.5
≤ 5 ≤ 0.6 ≥ 10 0.5

Performance research

http://www.mdpi.com/2073-4441/7/4/1595/htm


Landscaping

Landscaped areas should drain away from permeable pavingAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. to prevent sedimentsSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. from running onto the surface. Urban trees benefit from being surrounded by permeable pavementAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. rather than imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. cover, because their roots receive more air and water, and pavers used around the base of a tree can be removed as the tree grows.

Performance

Starting after TRIECA (end March) members of STEP will be undertaking a literature review on the performance of our most popular BMPsThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.. The results will be combined with the information we have to date from the development of the Treatment Train Tool and agreed performance metrics established. Until then, please feel free to continue to ask questions via email or the feedback box below.

Permeable pavers can be classified into two categories according to the infiltration rateThe rate at which stormwater percolates into the subsoil measured in inches per hour. of the underlying subsoil:

  • Full InfiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.: Full infiltration designs are more effective, because little if any of the pollutants generated on the impermeable surfaces leave the site as surface runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.
  • Partial InfiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.: Partial infiltration designs with underdrains generate more runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.

Studies in North Carolina have shown the average curve number of permeable pavements to range from a low of 45 to a high of 89. [6]
Partial infiltration designs with underdrains generate more runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface., and as a result, are often used in studies investigating the water quality impact of permeable pavements on surface waters. These studies show load reductions above 50% for total suspended solids, most metals and hydrocarbons [7][8]
As with all stormwater infiltration practices, risk of groundwater contamination from infiltration of runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. laden with road de-icing salt constituents (typically sodium and chloride) is a significant concern. Chloride ions are extremely mobile in the soil and are readily transported by percolating water to aquifersLayer of rock or soil that holds or transmits water..

Construction Considerations

Construction of permeable pavementAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. is a specialized project and should involve experienced contractors. The following general recommendations apply:

  • SedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. Control: The treatment area should be fully protected during construction so that no sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. reaches the permeable pavementAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. system and proper erosion and sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. controls must be maintained on site.
  • Weather: Porous asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. and pervious concrete will not properly pour and set in extremely high or low temperatures [9]. One benefit to using permeable pavers is that their installation is not weather dependent.
  • Pavement placement: Properly installed permeable pavementAn alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil. requires trained and experienced producers and construction contractors.

Inspection and Maintenance

Permeable pavements require regular inspection and maintenance to ensure proper functioning. The limiting factor for permeable pavers is clogging within the aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. layers, filler, or underdrainA perforated pipe used to assist the draining of soils.. Ideally, signs should be posted on the site identifying permeable paver and porous pavement areas. This can also serve as a public awareness and education opportunity. See: Permeable paving: Maintenance

Life cycle costs

Initial construction costs for permeable pavements are typically higher than conventional asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. pavement surfaces, largely due to thicker aggregateA broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations. 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 BMPsThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.. They combine parking, stormwater infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface., retention, and detentionThe temporary storage of stormwater to control discharge rates, and allow for sedimentation. into one facility. See also: Cost analysis resources

Proprietary Links

In our effort to make this guide as functional as possible, we have decided to include proprietary systems and links to manufacturers websites.
Inclusion of such links does not constitute endorsement by the Sustainable Technologies Evaluation Program.
Lists are ordered alphabetically; link updates are welcomed using the form below.

Pre-cast

Poured in place


  1. Porosity of Structural Backfill, Tech Sheet #1, Stormtech, Nov 2012, http://www.stormtech.com/download_files/pdf/techsheet1.pdf accessed 16 October 2017
  2. 2.0 2.1 2.2 Judge, Aaron, "Measurement of the Hydraulic Conductivity of Gravels Using a Laboratory Permeameter and Silty Sands Using Field Testing with Observation Wells" (2013). Dissertations. 746. http://scholarworks.umass.edu/open_access_dissertations/746
  3. Newman AP, Coupe SJ, Spicer GE, Lynch D, Robinson K. MAINTENANCE OF OIL-DEGRADING PERMEABLE PAVEMENTS: MICROBES, NUTRIENTS AND LONG-TERM WATER QUALITY PROVISION. https://www.icpi.org/sites/default/files/techpapers/1309.pdf. Accessed July 17, 2017.
  4. Paul P, Tota-Maharaj K. Laboratory Studies on Granular Filters and Their Relationship to Geotextiles for Stormwater Pollutant Reduction. Water. 2015;7(4):1595-1609. doi:10.3390/w7041595.
  5. ONTARIO PROVINCIAL STANDARD SPECIFICATION METRIC OPSS 1860 MATERIAL SPECIFICATION FOR GEOTEXTILES. 2012. http://www.raqsb.mto.gov.on.ca/techpubs/OPS.nsf/0/2ccb9847eb6c56738525808200628de1/$FILE/OPSS%201860%20Apr12.pdf. Accessed July 17, 2017
  6. Bean, E.Z., Hunt, W, F., Bidelspach, D.A. 2007a. Evaluation of Four Permeable Pavement Sites in Eastern North Carolina for Runoff Reduction and Water Quality Impacts. Journal of Irrigation and Drainage Engineering. Vol. 133. No. 6. pp. 583-592.
  7. 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
  8. Pratt, C.J., Mantle, J.D.G., Schofield, P.A. 1995. UK research into the performance of permeable pavement reservoir structures in controlling stormwater discharge quantity and quality. Water Science Technology. Vol. 32. No. 1. pp. 63-69.
  9. City of Portland. 2004. Portland Stormwater Management Manual. Prepared by the Bureau of Environmental Services (BES). Portland, OR.