Changes

==Overview==

==Overview==

[[Infiltration chambers]] include a range of proprietary manufactured, modular structures installed underground (embedded in clean, crushed angular [[stone]]) to create large void spaces that temporarily store and infiltrate runoff into the underlying native soil. Typically installed under parking or landscaped areas, they can be used in various configurations. They are well suited to sites where available land area is limited, or where it is desirable for the facility to have a minimal surface footprint. They can be designed with enough load bearing capacity to support the weight of structures above them, meaning that they can be installed below parking lots, sports fields, etc.

[[Infiltration chambers]] include a range of proprietary manufactured, modular structures installed underground (embedded in clean, crushed angular [[stone]]) to create large void spaces that temporarily store and infiltrate runoff into the underlying native soil. Typically installed under parking or landscaped areas, they can be used in various configurations. They are well suited to sites where available land area is limited, or where it is desirable for the facility to have a minimal surface footprint. They can be designed with enough load bearing capacity to support the weight of structures above them, meaning that they can be installed below parking lots, sports fields, etc.

STEP has prepared life cycle costs estimates for infiltration chamber systems located on highly permeable native soil (Full Infiltration design), and moderately permeable native soil (Partial Infiltration design) scenarios for comparison. Cost estimates are based on a 2,000 m² asphalt drainage area, runoff control target of 25 mm depth and 82 and 163 hour drainage periods for Full and Partial Infiltration Design scenarios respectively, 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].

STEP has prepared a life cycle cost estimate for infiltration chamber systems located on highly permeable native soil (Full Infiltration design) for comparison. Cost estimates are based on a 2,000 m² asphalt drainage area, runoff control target of 25 mm depth and 82 hour drainage period, 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, and Partial Infiltration Design scenarios were assumed to be 20 mm/h and 10 mm/h respectively, and a safety factor of 2.5 was applied to calculate the design infiltration rate.  

* Native soil infiltration rates for Full Infiltration Design scenarios were assumed to be 20 mm/h, 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, and removal of sediment from pretreatment structures annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ chamber system water level monitoring during natural storm events.

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, and removal of sediment from pretreatment structures annually. Verification inspections are included every 5 years to confirm adequate maintenance, and every 15 years to confirm adequate drainage performance through in-situ chamber system water level monitoring during natural storm events.

* Infiltration chamber system length of 5 metres and composed of 22 chambers in total.

* Infiltration chamber system length of 5 metres.

* Infiltration chamber height of 0.762 metres.

* Infiltration chamber system height of 0.762 metres.

* 50 mm dia. clear stone aggregate bedding depth (below and above chamber system) of 152 millimetres.

* 50 mm dia. clear stone aggregate bedding depth (below and above chamber system) of 152 millimetres.

* Two (2) maintenance holes providing access to infiltration chamber system inlet and outlet structures.

* Two (2) maintenance holes providing access to infiltration chamber system inlet and outlet structures.

===Notes===

===Notes===

* Designs include [[pretreatment]] through hydrodynamic separator ([[Oil and Grit Separator]] and A "Sediment Trap" or Isolated chamber row).

* Design include [[pretreatment]] through hydrodynamic separator ([[Oil and Grit Separator| i.e., oil and grit separator]]) and isolated chamber row.

* 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.

* All cost estimates are in Canadian dollars and represent the net present value (NPV) as the tool takes into account average annual interest and discount rates over the 25 and 50 year operating life cycle periods.

* All cost estimates are in Canadian dollars and represent the net present value (NPV) as the tool takes into account average annual interest and discount rates over the 25 and 50 year operating life cycle periods.

* Unit costs are based on 2018 RSMeans standard union pricing.

* Unit costs are based on 2018 RSMeans standard union pricing.

* Additional costs associated with retrofit or redevelopment contexts is assumed to be 16% of the cost estimate for new (greenfield) construction contexts.

* Additional costs associated with retrofit or redevelopment contexts is assumed to be 16% of the cost estimate for new (greenfield) construction contexts.

** Retrofit construction cost estimates are included in the 'Costs Summary' section for comparison.<br>

** Retrofit construction cost estimates are included in the 'Costs Summary' section for comparison.<br>

==Construction Costs==

==Construction Costs==

[[File:ConstructionTable InfilChamb Full Infil.PNG|thumb|left|610px|'''Construction Costs Per Unit Drainage Area (CAD$/m²) - Full Infiltration Design, 25 mm Treatment''']]

[[File:ConstructionTable InfilChamb Full Infil 2023.PNG|thumb|center|900px|'''Construction Costs Per Unit Drainage Area (CAD$/m²) - Full Infiltration Design, 25 mm Retention''']]<br>

<small>'''Note:''' Click on image to enlarge to view associated construction cost estimates.</small><br>

 

 

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

 

 

As can be seen, regardless of design configuration, Material & Installation expenses represent the largest portion of total construction costs (75%).

As can be seen, regardless of design configuration, Material & Installation expenses represent the largest portion of total construction costs (75%).

==Life Cycle Costs==

==Life Cycle Costs==

Below are capital and life cycle cost estimates for the two [[Infiltration chambers|infiltration chamber]] 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 36% of total life cycle costs over the 25-year evaluation period, and increase to 48% of total life cycle costs over the 50-year period, due to increased levels of litter removal, clean out and disposal of collected sediment from the Isolated chamber row (every 4 - 8 years), cleaning out the catchbasin and the [[Oil and Grit Separator|Oil and Grit Separator/Hydrodynamic Separator]] annually.  

Below are capital and life cycle cost estimates for the [[Infiltration chambers|infiltration chamber]] design scenario over 25- and 50-year time periods. The estimate of maintenance and rehabilitation (life cycle) cost represents net present values. Operation and maintenance costs are predicted to represent 37% of total life cycle costs over the 25-year evaluation period, and increase to 49% of total life cycle costs over the 50-year period, due to cost associated with removal of sediment from the isolated chamber row pretreatment devices every 8 years.

 

===25-Year life cycle cost break down===

===25-Year life cycle cost break down===

[[File:25yr LCCT InfilChamb Full Infil.PNG|thumb|left|615px|'''Infiltration Trench: Full Infiltration''']]

[[File:25yr LCCT InfilChamb Full Infil 2023.PNG|thumb|center|900px|'''Infiltration Trench: Full Infiltration''']]<br>

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

 

</br>

 

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

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

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

[[File:50yr LCCT InfilChamb Full Infil.PNG|thumb|left|615px|'''Infiltration Chamber: Full Infiltration''']]

[[File:50yr LCCT InfilChamb Full Infil 2023.PNG|thumb|center|900px|'''Infiltration Chamber: Full Infiltration''']]<br>

 

 

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

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

==Cost Summary Tables==

==Cost Summary Tables==

Total life cycle cost estimates for the two [[Infiltration chambers|infiltration chamber]] configurations are the exact same with the total being ($60,831.76).<br>

Total life cycle cost estimate over the 50 year evaluation period for [[Infiltration chambers|infiltration chamber system]] on highly permeable native soil design scenario is $123,670.89.<br>

===Full Infiltration===

===Full Infiltration===

[[File:East Gwillimbury.png|800px|thumb|Example of "crate style" [[Infiltration chambers]] being installed in East Gwillimbury. Photo credit: [https://www.makeway.ca/products/stormwater-management-systems/ Make-Way Environmental Technologies Inc.]]

[[File:East Gwillimbury.png|400px|thumb|Example of "crate style" [[Infiltration chambers]] being installed in East Gwillimbury. Photo credit: [https://www.makeway.ca/products/stormwater-management-systems/ Make-Way Environmental Technologies Inc.]]

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

[[File:Design Table InfilChamb Full Infil 2023.PNG|830px]]<br>

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==References==

==References==