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Inspection and Maintenance: Bioretention & Bioswales (view source)
Revision as of 20:16, 8 April 2022
, 2 years ago→Inspection Time Commitments and Costs
==Inspection Time Commitments and Costs==
==Inspection Time Commitments and Costs==
Estimates are based on a typical partial infiltration bioretention design (i.e., includes a sub-drain); estimates for other designs (i.e., full infiltration and no-infiltration) can be found in the [https://sustainabletechnologies.ca/app/uploads/2016/08/LID-IM-Guide-7.1-Bioretention-and-Dry-Swales.pdf Low Impact Development (LID) Stormwater Management Practice Inspection and Maintenance Guide]
Estimates are based on a typical partial infiltration bioretention design (i.e., includes a sub-drain); estimates for other designs (i.e., full infiltration and no-infiltration) can be found in the [https://sustainabletechnologies.ca/app/uploads/2016/08/LID-IM-Guide-7.1-Bioretention-and-Dry-Swales.pdf Low Impact Development (LID) Stormwater Management Practice Inspection and Maintenance Guide]
[[File:Time commit cost.PNG|thumb|left|450px|General time commitments and costs for inspection of bioretention and dry swale features with partial infiltration (in 2016 $ figures).<ref>TRCA. 2018. Inspection and Maintenance of Stormwater Best Management Practices. Bioretention - Fact Sheet. https://sustainabletechnologies.ca/app/uploads/2018/02/Bioretention-and-Dry-Swales-Fact-Sheet.pdf</ref>]]
[[File:Cost per maintenance task.PNG|thumb|450px|Per-task cost estimates for maintenance and rehabilitation of a partial infiltration bioretention feature (in 2016 $ figures).<ref>TRCA. 2018. Inspection and Maintenance of Stormwater Best Management Practices. Bioretention - Fact Sheet. https://sustainabletechnologies.ca/app/uploads/2018/02/Bioretention-and-Dry-Swales-Fact-Sheet.pdf</ref>]]
[[File:Life cycle costs.PNG|thumb|center|450px|Construction and life cycle cost estimates for bioretention and dry swale features with partial infiltration (in 2016 $ figures).<ref>TRCA. 2018. Inspection and Maintenance of Stormwater Best Management Practices. Bioretention - Fact Sheet. https://sustainabletechnologies.ca/app/uploads/2018/02/Bioretention-and-Dry-Swales-Fact-Sheet.pdf</ref>]]
Estimates of the life cycle costs of inspection and maintenance have been produced using the latest version of the [[Cost analysis resources|LID Life Cycle Costing Tool]] for three design variations (full infiltration, partial infiltration and no infiltration) to assist stormwater infrastructure planners, designers and asset managers with planning and preparing budgets for potential LID features.
Assumptions for the above costs and the following table below are based on the following:
*Capital costs included within the category of construction include those related to site assessment, and conceptual and detailed design related tasks such as borehole analysis and soil testing. All material, delivery, labour, equipment (rental, operation, operator), hauling and disposal costs are accounted for within the construction costs of the facility. Standard union costs were derived from the RSMeans database in 2010 and have been adjusted for 5 year inflation of 8.79% (2010 to June, 2015).
**Costs include overhead and inflation to represent contractor pricing. It was assumed the practice is part of a new development (i.e., not a retrofit), thereby excluding (de)mobilization costs unless a particular piece of equipment would not normally have been present at the site. Additionally, it was assumed that excavated soil associated with construction of the BMP would be reused elsewhere on site. Overhead costs were presumed to consist of construction management (4.5%), design (2.5%), small tools (0.5%), clean up (0.3%) and other (2.2%).
*For maintenance frequencies and requirements and the life span of each practice are based on both literature and practical experience. Life cycle and associated maintenance costs are evaluated over a 50 year timeframe, which is the typical period over which infrastructure decisions are made.
*For [[bioretention]], it is assumed that some rehabilitation (e.g., rehabilitative maintenance) work will be needed on the filter bed surface once the BMP reaches 25 and 50 years of age in order to maintain functional drainage performance at an acceptable level. Included in the rehabilitation costs are (de)mobilization costs, as equipment would not have been present on site. Design costs were not included in the rehabilitation as it was assumed that the original LID practice design would be used to inform this work. The annual average maintenance cost does not include rehabilitation costs and therefore represents an average of routine maintenance tasks, as outlined in the Table under section, [[Inspection and Maintenance: Bioretention & Dry Swales#Routine Maintenance - Key Components and I&M Tasks|Routine Maintenance - Key Components and I&M Tasks]] above. All cost value estimates represent the net present value (NPV) as the calculation takes into account average annual interest (2%) and discount (3%) rates over the evaluation time periods.
==Inspection Field Data Sheet==
==Inspection Field Data Sheet==