Changes

Table below provides guidance on rehabilitation and repair work specific to vegetated/grass filter strips and soil amendments organized according to BMP component.

Table below provides guidance on rehabilitation and repair work specific to vegetated/grass filter strips and soil amendments organized according to BMP component.

   

   

[[File:Levelspread.jpg|thumb|430px|This clever design incorporates a level spreading device after a [[curb cut]] has narrowed the flow path. This kind of treatment train approach would provide an opportunity to provide [[pretreatment]] at the point of concentration. This repair helps to limit the potential of erosion occurring within the feature. Photo credit: [https://www.pca.state.mn.us/featured/when-it-rains-it-flows (MPCA, 204)]<ref>Minnesota Pollution Control Agency. 2014. When it rains, it flows. 6 May 2014. Accessed 156 July 2022. https://www.pca.state.mn.us/featured/when-it-rains-it-flows</ref>]]   

[[File:Levelspread.jpg|thumb|440px|This clever design incorporates a level spreading device after a [[curb cut]] has narrowed the flow path. This kind of treatment train approach would provide an opportunity to provide [[pretreatment]] at the point of concentration. This repair helps to limit the potential of erosion occurring within the feature. Photo credit: [https://www.pca.state.mn.us/featured/when-it-rains-it-flows (MPCA, 204)]<ref>Minnesota Pollution Control Agency. 2014. When it rains, it flows. 6 May 2014. Accessed 156 July 2022. https://www.pca.state.mn.us/featured/when-it-rains-it-flows</ref>]]   

*The annual average maintenance cost represents an average of routine maintenance tasks, as outlined above in [[Inspection and Maintenance: Vegetated Filter Strips#Routine Maintenance - Key Components and I&M Tasks|Routine Maintenance - Key Components and I&M Tasks]] All cost value estimates represent the NPV as the calculation takes into account average annual interest (2%) and discount (3%) rates over the evaluation time periods.

*The annual average maintenance cost represents an average of routine maintenance tasks, as outlined above in [[Inspection and Maintenance: Vegetated Filter Strips#Routine Maintenance - Key Components and I&M Tasks|Routine Maintenance - Key Components and I&M Tasks]] All cost value estimates represent the NPV as the calculation takes into account average annual interest (2%) and discount (3%) rates over the evaluation time periods.

*The CDA has been defined as 2,000 m<sup>2<sup> of impermeable pavement (e.g., road or parking area) which drains by sheet flow to a vegetated filter strip that is approximately 800 m<sup>2<sup> in area (I:P ratio of 2.5:1), 70 m long, 11.4 m wide and situated along the long edge of the paved area. The side slope is defined as 12.5:1 (8%). Water enters the BMP as sheet flow from a gravel diaphragm flow spreading device along the edge adjacent to the pavement. The BMP surface is planted with grass and does not include check dams, nor any pipes or culverts.

*The CDA has been defined as 2,000 m² of impermeable pavement (e.g., road or parking area) which drains by sheet flow to a vegetated filter strip that is approximately 800 m² in area (I:P ratio of 2.5:1), 70 m long, 11.4 m wide and situated along the long edge of the paved area. The side slope is defined as 12.5:1 (8%). Water enters the BMP as sheet flow from a gravel diaphragm flow spreading device along the edge adjacent to the pavement. The BMP surface is planted with grass and does not include check dams, nor any pipes or culverts.

*Estimates of the life cycle costs of vegetated filter strips and soil amendment areas in Canadian dollars per unit CDA ($/m<sup>2<sup>) are presented above. The [[Cost analysis resources|LCCT) allows users to select what BMP type and design variation applies, and to use the default assumptions to generate planning level cost estimates. Users can also input their own values relating to a site or area, design, unit costs, and inspection and maintenance task frequencies to generate customized cost estimates, specific to a certain project, context or stormwater infrastructure program. <br>

*Estimates of the life cycle costs of vegetated filter strips and soil amendment areas in Canadian dollars per unit CDA ($/m²) are presented above. The [[Cost analysis resources|LCCT) allows users to select what BMP type and design variation applies, and to use the default assumptions to generate planning level cost estimates. Users can also input their own values relating to a site or area, design, unit costs, and inspection and maintenance task frequencies to generate customized cost estimates, specific to a certain project, context or stormwater infrastructure program. <br>

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#Estimated life cycle costs represent NPV of associated costs in Canadian dollars per square metre of CDA ($/m<sup2<sup>).

#Estimated life cycle costs represent NPV of associated costs in Canadian dollars per square metre of CDA ($/m²).

#Average annual maintenance cost estimates represent NPV of all costs incurred over the time period and do not include rehabilitation costs.

#Average annual maintenance cost estimates represent NPV of all costs incurred over the time period and do not include rehabilitation costs.

#Rehabilitation cost estimates represent NPV of all costs related to repair work assumed to occur every 25 years including those associated with inspection and maintenance over a two (2) year establishment period for the plantings.

#Rehabilitation cost estimates represent NPV of all costs related to repair work assumed to occur every 25 years including those associated with inspection and maintenance over a two (2) year establishment period for the plantings.

#It is assumed that no rehabilitation is needed to maintain acceptable drainage performance over a 50 year evaluation period.

#It is assumed that no rehabilitation is needed to maintain acceptable drainage performance over a 50 year evaluation period.

#Maintenance and rehabilitation costs over a 25 year time period are estimated to be 3.52 to 5.42 times the original construction cost, for the Minimum Recommended and High Frequency maintenance scenarios respectively.

#Maintenance and rehabilitation costs over a 25 year time period are estimated to be 3.52 to 5.42 times the original construction cost, for the Minimum Recommended and High Frequency maintenance scenarios respectively.

#Maintenance and rehabilitation costs over a 50 year time period are estimated to be 6.16 and 9.57 times  the original construction cost for the Minimum Recommended and High Frequency maintenance scenarios respectively.

#Maintenance and rehabilitation costs over a 50 year time period are estimated to be 6.16 and 9.57 times  the original construction cost for the Minimum Recommended and High Frequency maintenance scenarios respectively.</small>