Changes

==Overview==

==Overview==

[[Vegetated filter strips]] (A.K.A: buffer strips and grassed filter strips) are gently sloping, densely vegetated areas that treat runoff as sheet flow from adjacent impervious areas. They slow runoff velocity and filter out suspended sediment and associated pollutants, and provide some infiltration into underlying soils. Vegetated filter strips are generally used as [[pretreatment]] to other LID practices. Finally, filter strips also provide a convenient location for snow storage and treatment during the winter months. 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].

[[Vegetated filter strips]] (A.K.A: buffer strips and grassed filter strips) are gently sloping, densely vegetated areas that treat runoff as sheet flow from adjacent impervious areas. They slow runoff velocity and filter out suspended sediment and associated pollutants, and provide some infiltration into underlying soils. Vegetated filter strips are generally used as [[pretreatment]] to other LID practices. Finally, filter strips also provide a convenient location for snow storage and treatment during the winter months. 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].

==Design Assumptions==

==Design Assumptions==

==Life Cycle Costs==

==Life Cycle Costs==

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.

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 46% of total life cycle costs over the 25-year evaluation period, and increase to 60% of total life cycle costs over the 50-year period, due to increased levels of litter removal, vaccuum cleaning of the associated catchbasin, watering during the first and 2nd years (establishment period), annual watering, drought watering, mowing and aerating the grass, weeding and pruning and replacing any wilting/dying sections with new sod.

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

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

==Cost Summary Tables==

==Cost Summary Tables==

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>

Total life cycle cost estimates for a [[Vegetated filter strips|Vegetated filter strip]], Non-Infiltrating configuration is ($41,448.47). <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: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:Filter bed grass pass.png|500px|thumb|Exampel of a mature filter strip beside a major highway, Washington State, U.S. (Photo Source: Washington State Department of Transportation, 2018)<ref>Washington State Department of Transportation. 2018. Vegetated Filter Strips: Low-impact development fact sheet. Authored by: Maria Cahill, Derek Godwin, and Jenna Tilt. Published June 2018. Accessed: 14 July 2022. https://catalog.extension.oregonstate.edu/em9208/html</ref>]]

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

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

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==References==

==References==