Changes

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 rate for Full Infiltration Design scenario was 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, 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)

* Ditch inlet catch basin structure located at furthest downgradient end, with connection to storm sewer pipe, included as the outlet.  

* Designed with a trapezoidal or triangular cross section.

* Operation and maintenance (O&M) cost estimates assume annual inspections, removal of trash and debris twice a year, removal of sediment from curb inlets and outlet catch basin annually, and removal of weeds twice a year. 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.

* Impervious drainage area to pervious swale footprint area of 10:1 (tool default value).

* Designed with a bottom width between 0.6-2.4 m (allows shallow flows and adequate water treatment).

* Designed with a trapezoidal cross section with a top width of 4.75 m, bottom width of 0.75 m, and 2.5:1 side slopes (tool default values).

* Longitudinal slope should be between 0.5 and 4%. Check dams should be incorporated on slopes greater than 3%.

* Swale depth of 0.5 m, bottom length of 42.11 m and surface area at top of 200 m2.

* Side slopes should be flat to aid in providing pre-treatment for lateral incoming flows and maximize swale filtering surface.

* Longitudinal slope of 3%.

* Steeper side slopes may be susceptible to erosion from incoming lateral flows. A maximum slope of 2.5:1 is recommended (Tool default).

* Includes concrete curb check dams (0.3 m in height each) for every 10 m of swale length (4 in total).

* Maximum flow depth should be 50% of grass height for regularly mown swales, to maximum of 75 mm.

* Includes a 8.4 m wide driveway and 300 mm diameter culvert crossing.

* For infrequently mown swales, STEP recommends maximum flows of 33% of vegetation height.

* Designed for a maximum flow velocity of 0.3 m/s.

* Designed for a maximum velocity of 0.3 m/s.

* Convey locally required design storm (~10 mm year storm) at non-erosive velocities.

===Notes===

===Notes===

* The Tool assumes an in-line system.

* Design includes [[pretreatment]] through stone diaphragms at [[Curb cuts|curb inlets]].

* The Tool assumed curb-and-gutter around the circumference of the facility with curb-cut inlets every 6 to 0.5 meter squared and stone splash pads.  

* Operation and maintenance cost estimates assume rehabilitation of the swale surface is required after 25 years of operation.

* The greater the slope, the more check dams placed by the Tool. The unit cost for check dams is for the amount of material required, not number of dams.

* If configuration include driveway (2 laned), a culvert pipe connects the enhanced grass swale (EGS) and an extra 0.1m of gravel is added beneath culvert.

* Swales which cross multiple driveways or smaller driveways can be accounted for by multiplying or dividing these costs in the "Additional Costs" cells.

* 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.

==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 EnhancedSwales Full Infil 2023.PNG|thumb|center|950px|'''Construction Costs Per Unit Drainage Area (CAD$/m²) - Full Infiltration Design, 25 mm Treatment''']]

Above you can find a cost breakdown of a 1000m² LID configuration:<br>

Above you can find a breakdown of construction costs by expense type for a 200 m² surface area facility (I:P area ratio of 10:1):<br>

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

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

Material & Installation expenses represent the largest portion of total construction costs (50%).

Material & Installation expenses represent the largest portion of total construction costs (55%).

==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 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 39% of total life cycle costs over the 25-year evaluation period, and increase to 54% of total life cycle costs over the 50-year period, due to swale surface rehabilitation costs assumed to be required after 25 years of operation.

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

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

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

[[File:25yr LCCT EnhancedSwales Full Infil 2023.PNG|thumb|center|900px|'''Enhanced Swales: Full 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|'''Enhanced Swales: Full Infiltration''']]

[[File:50yr LCCT EnhancedSwales Full Infil 2023.PNG|thumb|center|900px|'''Enhanced Swales: Full 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 estimate over the 50 year evaluation period for the [[Enhanced swale]] Full Infiltration design configuration is ($65,021.40), making it one of the cheapest LID BMP options.<br>

===Full Infiltration===

===Full Infiltration===

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

[[File:CVC Office, Grass Swale.JPG|650px|thumb|Enhanced Grass [[swale]] in CVC headquarters parking lot, Mississauga ON.]]

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

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

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