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Permeable pavements: Life Cycle Costs (view source)
Revision as of 21:24, 13 December 2022
, 2 years agoCreated page with "thumb|500px|Placement of permeable pavers during construction. {{TOClimit|2}} ==Overview== 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..."
[[PermeablePavementConstruction.jpg|thumb|500px|Placement of permeable pavers during construction.]]
{{TOClimit|2}}
==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 interlocking pavers (concrete or composite materials)
• grid systems (concrete or composite materials)
• pervious concrete (poured-in-place or pre-cast)
• porous asphalt
• permeable articulating block/mat systems
For the sake of this page and associated costs/figures below the inmformation found here relate to '''Permeable Pavers''', for costs and information associated with [[LID LCCT: Porous Asphalt|Porous Asphalt click here]]. STEP conducted life cycle costs estimates for each of permeable pavements 3 design configurations which can be viewed below. To design your own life cycle cost estimates that can be adapted to fit your project budget and unique development needs access the updated [https://sustainabletechnologies.ca/lid-lcct/ LCCT Tool here].
==Design Guidance==
Bioretention is an ideal technology for fitting functional vegetation into urban landscapes and treating runoff collected from nearby impervious surfaces.
Components include: a 'filter bed' with [[filter media]], storage layer of [[reservoir aggregate]], [[planting]] and a finishing surface layer of [[mulch]] and/or [[stone]].
Additional components include an [[underdrain]] to remove excess water and soil additives to enhance [[Nutrients|pollutant removal]]. <br>
Tool defaults based on STEP recommendations:
* Maximum drainage area to surface area ratio of 20:1
* Default depth of 0.75 meters.
* Default mulch depth of 75 millimeters.
* An underdrain (minimum 200 mm perforated pipe) is only needed when native soil infiltration is less than 15 mm/hr or infiltration is precluded.
===Design Notes===
* Designs include [[pretreatment]] through stone diaphragms at [[Curb cuts|curb inlets]]. Pretreatment through settling forebay and vegetated filter strip not included.
* The tool calculates costs for new designs and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal. Mobilization and demobilization costs not included. The tool adds 10% contingency and additional overhead.
* Design and Engineering cost estimates are not calculated by the tool and must be supplied by the user.
* Unit costs are based on 2018 pricing; the tool automatically adds inflation. See the Assumptions sheet in the tool for further details.
* The cost of retrofitting is ~16% higher than the cost of new construction.
** Retrofit costs are included in the 'Costs Summary' section and can be added to the Total Construction Cost for increased accuracy.<br>
<small>'''Note''': Bioretention (all 3 design scenarios): Includes pretreatment sump at inlet and assumes that rehabilitation of filter media bed is performed at 25 years.</small>
==Construction Costs==
[[File:Construction Breakdown Bio No Infil.PNG|thumb|right|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - Full Infiltration Design, 25 mm Retention''']]
[[File:Construction Breakdown Bio Partial Infil.PNG|thumb|left|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - Partial Infiltration Design, 25 mm Retention''']]
[[File:Construction Breakdown Bio Full Infil.PNG|thumb|center|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - No Infiltration Design, 25 mm Treatment''']]
<small>'''Note:''' Please click on each image to enlarge to view associated construction cost results.</small><br>
Above you can find a cost breakdown of a 250m<sup>2</sup> in three different configurations:<br>
#[[Stormwater planters|non-infiltrating/filtration only Bioretention]],
#[[Bioretention: Partial infiltration]]
#[[Bioretention: Full infiltration]]
As can be seen the greatest cost for this practice (regardless of configuration type) will be Material & Installation, which include costly components such as the, [[Liner|impermeable membrane/liner]] appropriate [[planting]] and [[vegetation]] selection, [[underdrain]], [[filter media]] and the stone storage layer or [[Bioretention: Internal water storage|Internal water storage zone (IWSZ)]].
==Life Cycle Costs==
Below are both the capital and life cycle costs of the three [[bioretention]] configuration practices 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.
Looking at the pie charts below for each configuration we can see that they are all relatively close to being the same cost with a variation of a few hundred dollars between each over both a 25 and 50-year time horizon. The percentage of the [[Bioretention: Full infiltration|Full Infitlration]] configuration is greater than the other two due to the lesser cost of the overall installation for material and Installation, (no underdrains, no gravel storage layer or impermeable membrane, etc.).
===25-Year life cycle cost break down===
[[File:25yr LCCT Bio Full Infil.PNG|thumb|left|400px|'''Bioretention: Full infiltration''']]
[[File:25yr LCCT Bio No Infil.PNG|thumb|right|400px|''' Bioretention: Non-infiltrating''']]
[[File:25yr LCCT Bio Partial Infil.PNG|thumb|center|400px|'''Bioretention: Partial infiltration''']]
<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>
===50-Year life cycle cost break down===
[[File:50yr LCCT Bio Full Infil.PNG|thumb|left|400px|'''Bioretention: Full infiltration''']]
[[File:50yr LCCT Bio No Infil.PNG|thumb|right|400px|''' Bioretention: Non-infiltrating''']]
[[File:50yr LCCT Bio Partial Infil.PNG|thumb|center|400px|'''Bioretention: Partial infiltration''']]
<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>
==Total Cost & Design Summary==
As previously discussed the three [[Bioretention]] configurations total cost summary vary greatly dependent on whether you want you feature to possess full infiltration, no infiltration, or partial infiltration. In short the most expensive of this options is the [[Bioretention: Partial infiltration]] option ($113,800.83 vs. $109,113.76 - no infiltration and $80,392.33 - full infiltration). The same can be said for construction + associated retrofit costs with each configuration design ($132,008.97 vs. $126,571.96 - no infiltration and $93,255.10 - full infiltration) This configuration allows for the greatest storage volume (187.5 m<sup>3</sup>) compared to its counterparts at 145<sup>3</sup> for no infiltration and 107.5<sup>3</sup> for full infiltration; all while having the exact same surface area footprint of 250m<sup>2</sup>. As a note it is important to understand your site's surrounding native soil infiltration rate to ensure you are selecting the appropriate design.<br>
A final note in the accuracy of the LCCT. A follow up sensitivity analysis study was conducted by CVC & STEP back in 2019 to test the tool's accuracy. The analysis took designs from 6 completed projects (4 [[bioretention]], 1 [[permeable pavement]], and 1 [[infiltration trench]]), and ran them through the tool comparing construction costing results from the LCCT to actual construction costs for the projects. The accuracy target set for the tool was plus-or-minus 30% of actual construction costs.<br>
'''The analysis found that the tool was on average (±14%) to 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>
===Full Infiltration===
[[File:Picture for page.PNG|thumb|700px|STEP staff member conducting performance analysis of a bioretention feature at Kortright Centre in Vaughan, ON. (Source: STEP, 2016<ref>Performance Comparison of Surface and Underground Stormwater Infiltration Practices - TECHNICAL BRIEF. Low Impact Development Series. https://sustainabletechnologies.ca/app/uploads/2016/08/BioVSTrench_TechBrief__July2015.pdf</ref>)]]
[[File:Design Table Bio Full Infil.PNG|700px]]<br>
</br>
===Partial Infiltration===
[[File:Design Table Bio Partial Infil.PNG|700px]]<br>
</br>
===Non-Infiltrating/filtration only===
[[File:Design Table Bio No Infil.PNG|700px]]<br>
==References==
{{TOClimit|2}}
==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 interlocking pavers (concrete or composite materials)
• grid systems (concrete or composite materials)
• pervious concrete (poured-in-place or pre-cast)
• porous asphalt
• permeable articulating block/mat systems
For the sake of this page and associated costs/figures below the inmformation found here relate to '''Permeable Pavers''', for costs and information associated with [[LID LCCT: Porous Asphalt|Porous Asphalt click here]]. STEP conducted life cycle costs estimates for each of permeable pavements 3 design configurations which can be viewed below. To design your own life cycle cost estimates that can be adapted to fit your project budget and unique development needs access the updated [https://sustainabletechnologies.ca/lid-lcct/ LCCT Tool here].
==Design Guidance==
Bioretention is an ideal technology for fitting functional vegetation into urban landscapes and treating runoff collected from nearby impervious surfaces.
Components include: a 'filter bed' with [[filter media]], storage layer of [[reservoir aggregate]], [[planting]] and a finishing surface layer of [[mulch]] and/or [[stone]].
Additional components include an [[underdrain]] to remove excess water and soil additives to enhance [[Nutrients|pollutant removal]]. <br>
Tool defaults based on STEP recommendations:
* Maximum drainage area to surface area ratio of 20:1
* Default depth of 0.75 meters.
* Default mulch depth of 75 millimeters.
* An underdrain (minimum 200 mm perforated pipe) is only needed when native soil infiltration is less than 15 mm/hr or infiltration is precluded.
===Design Notes===
* Designs include [[pretreatment]] through stone diaphragms at [[Curb cuts|curb inlets]]. Pretreatment through settling forebay and vegetated filter strip not included.
* The tool calculates costs for new designs and includes costs for contractor overhead and profit, material, delivery, labour, equipment (rental, operating and operator costs), hauling and disposal. Mobilization and demobilization costs not included. The tool adds 10% contingency and additional overhead.
* Design and Engineering cost estimates are not calculated by the tool and must be supplied by the user.
* Unit costs are based on 2018 pricing; the tool automatically adds inflation. See the Assumptions sheet in the tool for further details.
* The cost of retrofitting is ~16% higher than the cost of new construction.
** Retrofit costs are included in the 'Costs Summary' section and can be added to the Total Construction Cost for increased accuracy.<br>
<small>'''Note''': Bioretention (all 3 design scenarios): Includes pretreatment sump at inlet and assumes that rehabilitation of filter media bed is performed at 25 years.</small>
==Construction Costs==
[[File:Construction Breakdown Bio No Infil.PNG|thumb|right|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - Full Infiltration Design, 25 mm Retention''']]
[[File:Construction Breakdown Bio Partial Infil.PNG|thumb|left|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - Partial Infiltration Design, 25 mm Retention''']]
[[File:Construction Breakdown Bio Full Infil.PNG|thumb|center|400px|'''Construction Costs Per Unit Drainage Area (CAD$/m<sup>2</sup>) - No Infiltration Design, 25 mm Treatment''']]
<small>'''Note:''' Please click on each image to enlarge to view associated construction cost results.</small><br>
Above you can find a cost breakdown of a 250m<sup>2</sup> in three different configurations:<br>
#[[Stormwater planters|non-infiltrating/filtration only Bioretention]],
#[[Bioretention: Partial infiltration]]
#[[Bioretention: Full infiltration]]
As can be seen the greatest cost for this practice (regardless of configuration type) will be Material & Installation, which include costly components such as the, [[Liner|impermeable membrane/liner]] appropriate [[planting]] and [[vegetation]] selection, [[underdrain]], [[filter media]] and the stone storage layer or [[Bioretention: Internal water storage|Internal water storage zone (IWSZ)]].
==Life Cycle Costs==
Below are both the capital and life cycle costs of the three [[bioretention]] configuration practices 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.
Looking at the pie charts below for each configuration we can see that they are all relatively close to being the same cost with a variation of a few hundred dollars between each over both a 25 and 50-year time horizon. The percentage of the [[Bioretention: Full infiltration|Full Infitlration]] configuration is greater than the other two due to the lesser cost of the overall installation for material and Installation, (no underdrains, no gravel storage layer or impermeable membrane, etc.).
===25-Year life cycle cost break down===
[[File:25yr LCCT Bio Full Infil.PNG|thumb|left|400px|'''Bioretention: Full infiltration''']]
[[File:25yr LCCT Bio No Infil.PNG|thumb|right|400px|''' Bioretention: Non-infiltrating''']]
[[File:25yr LCCT Bio Partial Infil.PNG|thumb|center|400px|'''Bioretention: Partial infiltration''']]
<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>
===50-Year life cycle cost break down===
[[File:50yr LCCT Bio Full Infil.PNG|thumb|left|400px|'''Bioretention: Full infiltration''']]
[[File:50yr LCCT Bio No Infil.PNG|thumb|right|400px|''' Bioretention: Non-infiltrating''']]
[[File:50yr LCCT Bio Partial Infil.PNG|thumb|center|400px|'''Bioretention: Partial infiltration''']]
<small>'''Note:''' Please click on each image to enlarge to view associated life cycle cost results.</small><br>
==Total Cost & Design Summary==
As previously discussed the three [[Bioretention]] configurations total cost summary vary greatly dependent on whether you want you feature to possess full infiltration, no infiltration, or partial infiltration. In short the most expensive of this options is the [[Bioretention: Partial infiltration]] option ($113,800.83 vs. $109,113.76 - no infiltration and $80,392.33 - full infiltration). The same can be said for construction + associated retrofit costs with each configuration design ($132,008.97 vs. $126,571.96 - no infiltration and $93,255.10 - full infiltration) This configuration allows for the greatest storage volume (187.5 m<sup>3</sup>) compared to its counterparts at 145<sup>3</sup> for no infiltration and 107.5<sup>3</sup> for full infiltration; all while having the exact same surface area footprint of 250m<sup>2</sup>. As a note it is important to understand your site's surrounding native soil infiltration rate to ensure you are selecting the appropriate design.<br>
A final note in the accuracy of the LCCT. A follow up sensitivity analysis study was conducted by CVC & STEP back in 2019 to test the tool's accuracy. The analysis took designs from 6 completed projects (4 [[bioretention]], 1 [[permeable pavement]], and 1 [[infiltration trench]]), and ran them through the tool comparing construction costing results from the LCCT to actual construction costs for the projects. The accuracy target set for the tool was plus-or-minus 30% of actual construction costs.<br>
'''The analysis found that the tool was on average (±14%) to 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>
===Full Infiltration===
[[File:Picture for page.PNG|thumb|700px|STEP staff member conducting performance analysis of a bioretention feature at Kortright Centre in Vaughan, ON. (Source: STEP, 2016<ref>Performance Comparison of Surface and Underground Stormwater Infiltration Practices - TECHNICAL BRIEF. Low Impact Development Series. https://sustainabletechnologies.ca/app/uploads/2016/08/BioVSTrench_TechBrief__July2015.pdf</ref>)]]
[[File:Design Table Bio Full Infil.PNG|700px]]<br>
</br>
===Partial Infiltration===
[[File:Design Table Bio Partial Infil.PNG|700px]]<br>
</br>
===Non-Infiltrating/filtration only===
[[File:Design Table Bio No Infil.PNG|700px]]<br>
==References==