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[[File:MLSmith swale.jpg||thumb|500px|[[Enhanced swale]] with rocky [[check dams]] and a metal [[overflow]] grate in Northgate Mall parking lot, Seattle. Photo credit: [[Acknowledgements| MLSmith]].]]

[[File:PEP Design Kempen RWH.PNG|thumb|600px|A common [[Rainwater harvesting]] design configuration for residential use, with its various components shown. [[Acknowledgements| PEP Design Kempen]].]]

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==Overview==

==Overview==

[[Rainwater harvesting]] is the process of intercepting, conveying and storing rainfall for future use. The term “rainwater harvesting” (RWH) is used herein to refer to capturing rainfall onto rooftops (i.e. “roofwater”) and stormwater runoff from the ground surface (i.e. “stormwater”), and then reusing for irrigation or other greywater-approved uses. The rain that falls upon a catchment surface, such as a roof, is collected and conveyed into a storage facility. Storage tanks, a common method for storage, range in size from rain barrels for residential land uses (typically 190 to 400 litres in size), to large cisterns for industrial, commercial and institutional land uses. A typical pre-fabricated cistern can range from 750 to 40,000 litres in size. STEP has prepared life cycle costs estimates for each design configuration, based on a 2,000 m² road 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].

[[Rainwater harvesting]] is the process of intercepting, conveying and storing rainfall for future use. The term “rainwater harvesting” (RWH) is used herein to refer to capturing rainfall onto rooftops (i.e. “roofwater”) and stormwater runoff from the ground surface (i.e. “stormwater”), and then reusing for irrigation or other greywater-approved uses. The rain that falls upon a catchment surface, such as a roof, is collected and conveyed into a storage facility. Storage tanks, a common method for storage, range in size from rain barrels for residential land uses (typically 190 to 400 litres in size), to large cisterns for industrial, commercial and institutional land uses. A typical pre-fabricated cistern can range from 750 to 50,000 litres in size. STEP has prepared life cycle costs estimates for each design configuration, based on a 2,000 m² roof 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==

==Construction Costs==

==Construction Costs==

[[File:Construction Breakdown EnhancedSwales Full Infil.PNG|thumb|center|950px|'''Construction Costs Per Unit Drainage Area (CAD$/m²) - Full Infiltration Design, 25 mm Treatment''']]

[[File:Construction Breakdown RWH No Infil.PNG|thumb|center|950px|'''Construction Costs Per Unit Drainage Area (CAD$/m²) - No Infiltration Design, 25 mm Treatment''']]

Above you can find a cost breakdown of a 1000m² in two different configurations:<br>

Above you can find a cost breakdown of a below-ground concrete cistern that possesses a 50,000L capacity limit in the following configurations type:<br>

#[[Enhanced swales|Enhanced Swales: Full Infiltration]]  

#[[Rainwater harvesting|Rainwater Harvesting: No Infiltration]]  

As can be seen, regardless of design configuration, Material & Installation expenses represent the largest portion of total construction costs (50%).

The Material & Installation expenses represent the largest portion of total construction costs (84%).

==Life Cycle Costs==

==Life Cycle Costs==

Below are capital and life cycle cost estimates for the [[Enhanced swales]] Full Infiltration configuration 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 45% of total life cycle costs over the 25-year evaluation period, and increase to 59% of total life cycle costs over the 50-year period, due to increased levels of litter removal, watering (establishment period - years 1 & 2 / annually and / drought watering) cleaning out and vacuuming of the catchbasin, mowing, replacement of sod, weeding and pruning of the BMP's planted [[vegetation]].

Below are capital and life cycle cost estimates for an [[Rainwater harvesting|Underground Rainwater Cistern]], Non-Infiltrating configuration 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 18% of total life cycle costs over the 25-year evaluation period, and increase to 26% of total life cycle costs over the 50-year period, due to increased levels of litter removal, cleaning out of tank, cleaning the in-line filter, replacing components (pump and pressure tank), cistern pump performance testing.

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

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

[[File:25yr LCCT EnhancedSwales Full Infil.PNG|thumb|center|900px|'''Enhances Swales: Full Infiltration''']]

[[File:25yr LCCT RWH No Infil.PNG|thumb|center|900px|'''Rainwater Harvesting: No Infiltration''']]

<small>'''Note:''' Click on each image to enlarge to view associated life cycle cost estimate.</small><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 EnhancedSwales Full Infil.PNG|thumb|center|900px|'''Enhances Swales: Full Infiltration''']]

[[File:50yr LCCT RWH No Infil.PNG|thumb|center|900px|'''Rainwater Harvesting: No Infiltration''']]

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

<small>'''Note:''' Click on each 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 [[Enhanced swale]] Full Infiltration design configuration is ($23,451.36), makign it one of the cheapest LID BMP options.<br>

Total life cycle cost estimates for an [[Rainwater harvesting|Underground Rainwater Cistern]], Non-Infiltrating configuration is ($92,343.04), making it one of the cheapest LID BMP options.<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>

===Full Infiltration===

===Full Infiltration===

[[File:CVC Office, Grass Swale.JPG|500px|thumb|Enhanced Grass [[swale]] in CVC headquarters parking lot, Mississauga ON.]]

[[File:RWH rain barrel.PNG|500px|thumb|A residential [[rain barrels|rain barrel]] collecting roofwater from the house installed with a diverter to ensure water does not overflow the system when full and allows water to instead bypass the barrel and enter directly into the storm sewer through a storm lateral or enter an on site [[dry swale]] or [[infiltration trench]], if installed.]]

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

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

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==References==

==References==