Changes

==Overview==

==Overview==

[[Permeable pavement|Permeable Pavers]] are an alternative to traditional impervious pavements that allow stormwater to drain through them and into a storage reservoir below. Depending on the native soil properties and site constraints, the system may be designed for full infiltration, partial infiltration, or as a non-infiltrating detention and filtration only practice. They can be used for low traffic roads, parking, driveways, and walk ways, and are ideal where space for other surface BMPs is limited. Permeable pavement types include:

[[Permeable pavement|Permeable Pavers]] are an alternative to traditional impervious pavements that allow stormwater to drain through them and into a storage reservoir aggregate layer below. Depending on the native soil properties and site constraints, the system may be designed for full infiltration, partial infiltration, or as a non-infiltrating detention and filtration only practice. They can be used for low traffic roads, parking, driveways, and walk ways, and are ideal where space for other surface BMPs is limited. Permeable pavement types include:

*permeable interlocking pavers (concrete or composite materials)

*permeable interlocking pavers (concrete or composite materials)

*grid systems (concrete or composite materials)

*grid systems (concrete or composite materials)

==Design Assumptions==

==Design Assumptions==

Permeable pavers are ideal for sites with limited space and projects such as low traffic roads, parking lots, driveways and walkways. Components include: interlocking pavers, precast pervious slabs, cast in place surface, bedding course, and underground storage layer. Additional components include an underdrain to remove excess water and soil additives to enhance pollutant removal.

Permeable pavers are ideal for sites with limited space and projects such as low traffic roads, parking lots, driveways and walkways. Components include: interlocking pavers, a bedding aggregate layer, a base aggregate layer, and a sub-base aggregate layer (or stone reservoir) for water storage. Optional components include an underdrain to remove excess water, flow restrictor to control the release rate of the facility, and surface drains to safely convey flows in excess of the storage capacity of the design.

Design and operation and maintenance program assumptions used to generate cost estimates are based on tool default values and the following STEP recommendations:

Design and operation and maintenance program assumptions used to generate cost estimates are based on tool default values and the following STEP recommendations:

*Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, and vacuum sweeping annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ surface infiltration rate testing.

*Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, and vacuum sweeping annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ surface infiltration rate testing.

* Impervious drainage area to permeable surface area (I:P area) ratio of 1:1

* Impervious drainage area to permeable surface area (I:P area) ratio of 1:1

* Default Bedding (2 to 5 mm dia. clear stone) depth of 50 millimetres.

* Default bedding aggregate (2 to 5 mm dia. clear stone) depth of 50 millimetres.

* Default Base (20 mm dia. clear stone) depth of 100 millimetres.

* Default base aggregate (20 mm dia. clear stone) depth of 100 millimetres.

* Default Sub-base (50 mm dia. clear stone) depth of 200 millimetres.

* Default sub-base aggregate (50 mm dia. clear stone) depth of 200 millimetres.

* A 150 mm diameter perforated underdrain pipe is included in Partial Infiltration and No Infiltration design configurations only.<br>

* A 150 mm diameter perforated underdrain pipe is included in Partial Infiltration and No Infiltration design configurations only.<br>

===Notes===

===Notes===

* Operation and maintenance cost estimates include replacement of joint stabilizing aggregate material removed by annual vacuum sweeping and assume no rehabilitation of the permeable pavement surface is required over the 50 year timeframe.

* Operation and maintenance cost estimates include replacement of joint stabilizing aggregate material removed by annual vacuum sweeping and some replacement of damaged pavers, but assume no rehabilitation of the permeable pavement surface is required to maintain acceptable drainage performance over the 50 year timeframe.

* The tool calculates costs for new (greenfield) development contexts and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal.  

* The tool calculates costs for new (greenfield) development contexts and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal.  

** Land value and equipment mobilization and demobilization costs are not included, assuming BMP construction is part of overall development site construction.

** Land value and equipment mobilization and demobilization costs are not included, assuming BMP construction is part of overall development site construction.

<small>'''Note:''' Please click on each image to enlarge to view associated construction cost results.</small><br>

<small>'''Note:''' Please click on each image to enlarge to view associated construction cost results.</small><br>

#[[Permeable pavements#Design|Non-infiltrating/filtration only Permeable Pavement]],  

#[[Permeable pavements#Design|Non-infiltrating/filtration only Permeable Pavement]],  

#[[Permeable pavements#Design|Partial infiltration Permeable Pavement]]

#[[Permeable pavements#Design|Partial infiltration Permeable Pavement]]

#[[Permeable pavements#Design|Full infiltration Permeable Pavement]]  

#[[Permeable pavements#Design|Full infiltration Permeable Pavement]]  

As can be seen, regardless of configuration type, Material & Installation expenses represent the largest portion of the total construction costs (82 to 85%). These include costly components such as the, [[Liner|impermeable membrane/liner]], the [[underdrain]], the [[Permeable pavements#Foundation Aggregates|sub-base]] of 50mm [[clear stone]], base of 19mm [[clear stone]] and the [[Bedding layer|bedding pavers themselves]].

As can be seen, regardless of outlet configuration, Material & Installation expenses represent the largest portion of the total construction costs (82 to 85%). These include costly components such as the [[Liner|impermeable membrane/liner]], [[underdrain]], [[Permeable pavements#Foundation Aggregates|sub-base layer]] of 50 mm dia. [[clear stone]], [[Permeable pavements#Foundation Aggregates|base layer]] of 19 mm dia. [[clear stone]], [[Bedding layer|bedding layer]] of 5 mm dia. [[clear stone]] and interlocking pavers themselves.

==Life Cycle Costs==

==Life Cycle Costs==

Below are both the capital and life cycle costs of the three [[permeable pavements|permeable pavement]] configurations over a 25- and 50-year time horizon based on a detailed assessment of local input costs, maintenance requirements, rehabilitation costs and design scenarios relevant to Canadian climates. The costs of maintenance and rehabilitation (Life cycle costs) are set at "Present Value" of these activities in 2022. The estimates of maintenance and rehabilitation (life cycle) costs represent net present values (NPV). Operation and maintenance costs are predicted to represent between 18 to 20% of total life cycle costs over the 25-year evaluation period, and increase to between 26 to 29% of total life cycle costs over the 50-year period, due to costs associated with increased surface vacuuming, replacement of joint material after vacuuming, restriping, replacement of pavers and cleaning out underground pipes (underdrain and overflow) to prevent [[clogging]] assumed to be continually required after 25 years of operation.

Below are capital and life cycle cost estimates for the three [[permeable pavements|permeable pavement]] configurations over 25- and 50-year time periods. The estimates of maintenance and rehabilitation (life cycle) costs represent net present values. Operation and maintenance costs are predicted to represent between 18 to 20% of total life cycle costs over the 25-year evaluation period, and increase to between 26 to 29% of total life cycle costs over the 50-year period, due to costs associated with restriping, replacement of limited number of pavers and flushing of underground pipes (underdrain and overflow) after 25 years of operation.  Estimates assume no rehabilitation of the permeable pavement surface is required to maintain acceptable drainage performance over the 50 year timeframe.

<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>

<small>'''Note:''' Click on each image to enlarge to view associated life cycle cost results.</small><br>

===50-Year life cycle cost break down===

===50-Year life cycle cost break down===

<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>

<small>'''Note:''' Click on each image to enlarge to view associated life cycle cost results.</small><br>

==Cost Summary Table ==

==Cost Summary Tables==

Total life cycle cost estimates for the three permeable pavement configurations vary substantially with the No Infiltration design being highest ($187,356.33), compared to the Partial Infiltration design ($168,085.10), and followed closely by the Full Infiltration design ($162,491.78).

Total life cycle cost estimates over the 50 year evaluation period for the three permeable pavement configurations vary substantially with the No Infiltration design being highest ($262,294.27), compared to the Partial Infiltration design ($242,444.90), and followed closely by the Full Infiltration design ($234,854.66).

It is notable that a sensitivity analysis was conducted in 2019 to compare construction cost estimates generated by the tool to actual costs of implemented projects. '''The analysis found that tool estimates were typically 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>.

It is notable that a sensitivity analysis was conducted in 2019 to compare construction cost estimates generated by the tool to actual costs of implemented projects. '''The analysis found that tool estimates were typically 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>.

[[File:PICPchicago.jpg|thumb|500px||Permeable Interlocking Concrete Pavement (PICP) on a narrow road between buildings in Chicago (Source: ICPI)]]

[[File:PICPchicago.jpg|thumb|500px||Permeable Interlocking Concrete Pavement (PICP) on a narrow road between buildings in Chicago (Source: ICPI)]]

[[File:Design Table PP Full Infil.PNG|700px]]<br>

[[File:Design Table PP Full Infil Update 2023.PNG|700px]]<br>

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===Partial Infiltration===

===Partial Infiltration===

[[File:Design Table PP Partial Infil.PNG|700px]]<br>

[[File:Design Table PP Partial Infil update 2023.PNG|700px]]<br>

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</br>

===Non-Infiltrating/filtration only===

===Non-Infiltrating/filtration only===

[[File:Design Table PP No Infil.PNG|700px]]<br>

[[File:Design Table PP No Infil update 2023.PNG|700px]]<br>

==References==

==References==