Changes

==Overview==

==Overview==

Given that [[Bioretention]] is a widely used name and a general "catch-all" term for most vegetated LID practices that temporarily store stormwater runoff in depressed planting beds there are a number of configurations of the feature that can be used in various contexts and environments. Depending on native soil infiltration rate and physical constraints, the facility may be designed without an [[underdrain]] for [[Bioretention: Full infiltration|full infiltration]], with an underdrain for [[Bioretention: Partial infiltration|partial infiltration]], or with an impermeable [[liner]] and underdrain for [[Stormwater planters|no infiltration/filtration only]] (i.e., a [[stormwater planters]] or biofilter) design. STEP has prepared life cycle costs estimates for each design configuration, based on a 2,000 m² asphalt drainage area, runoff control target of 25 mm depth and 72 hour drainage period, for comparison which can be viewed below. To generate your own life cycle cost estimates customized to the development context, design criteria, and constraints applicable to your site, access the updated [https://sustainabletechnologies.ca/lid-lcct/ LID Life Cycle Costing Tool (LCCT) here].

Given that [[Bioretention]] is a widely used name and a general "catch-all" term for most vegetated LID practices that temporarily store stormwater runoff in depressed planting beds there are a number of configurations of the feature that can be used in various contexts and environments. Depending on native soil infiltration rate and physical constraints, the facility may be designed without an [[underdrain]] for [[Bioretention: Full infiltration|full infiltration]], with an underdrain for [[Bioretention: Partial infiltration|partial infiltration]], or with an impermeable [[liner]] and underdrain for [[Stormwater planters|no infiltration/filtration only]] (i.e., a [[stormwater planters]] or biofilter) design. Optional components include a 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. STEP has prepared life cycle costs estimates for each design configuration, based on a 2,000 m² asphalt drainage area, runoff control target of 25 mm depth and 72 hour drainage period, for comparison which can be viewed below. To generate your own life cycle cost estimates customized to the development context, design criteria, and constraints applicable to your site, access the updated [https://sustainabletechnologies.ca/lid-lcct/ LID Life Cycle Costing Tool (LCCT) here].

==Design Assumptions==

==Design Assumptions==

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:

* Native soil infiltration rates for Full, Partial and No Infiltration Design scenarios were assumed to be 20 mm/h, 10 mm/h and 2 mm/h, respectively, and a safety factor of 2.5 was applied to calculate the design infiltration rate.  

* Native soil infiltration rates for Full, Partial and No Infiltration Design scenarios were assumed to be 20 mm/h, 10 mm/h and 2 mm/h, respectively, and a safety factor of 2.5 was applied to calculate the design infiltration rate.  

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, removal of sediment from pretreatment structures annually, and removal of weeds twice a year (where applicable). 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 (where applicable)

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, removal of sediment from pretreatment structures annually, and removal of weeds twice a year (where applicable). 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.

*Maximum impervious drainage area to permeable surface area (I:P area) ratio of 20:1.

*Maximum impervious drainage area to permeable surface area (I:P area) ratio of 20:1.

* Length to width ratio of bioretention area is 10:1.

* Length to width ratio of bioretention area is 10:1.

==Cost Summary Tables==

==Cost Summary Tables==

Total life cycle cost estimates for the three [[Bioretention]] configurations vary substantially with the [[Bioretention: Partial infiltration| Partial Infiltration]] design being highest ($113,800.83), followed closely by [[Stormwater planter| No Infiltration]] design ($109,113.76), and [[Bioretention: Full infiltration| Full Infiltration]] design being the lowest ($80,392.33).<br>

Total life cycle cost estimates over the 50 year evaluation period for the three [[Bioretention]] configurations vary substantially with the [[Bioretention: Partial infiltration| Partial Infiltration]] design being highest ($190,132.53), followed closely by [[Stormwater planter| No Infiltration]] design ($185,304.84), and [[Bioretention: Full infiltration| Full Infiltration]] design being the lowest ($153,805.69).<br>

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: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: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 Update.PNG|700px]]<br>

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

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===Partial Infiltration===

===Partial Infiltration===

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

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

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===No Infiltration (Filtration Only)===

===No Infiltration (Filtration Only)===

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

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

==References==

==References==