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Inspection and Maintenance: Vegetated Filter Strips (view source)
Revision as of 11:43, 15 July 2022
, 1 year agono edit summary
|[[File:Vegetation grass pass.JPG|315px|thumb|center|The vegetated filter strip is evenly covered with dense turf grass which helps to maintain its stormwater treatment function and aesthetic value. (Photo Source: Trinkaus Engineering))]]
|[[File:Vegetation grass pass.JPG|315px|thumb|center|The vegetated filter strip is evenly covered with dense turf grass which helps to maintain its stormwater treatment function and aesthetic value. (Photo Source: Trinkaus Engineering))]]
|[[File:Vegetation grass fail.JPG|315px|thumb|center| Major portions of the filter strip contain bare soil or dead vegetation which reduces its aesthetic value and could be negatively affecting its stormwater treatment function]]
|[[File:Vegetation grass fail.JPG|315px|thumb|center| Major portions of the filter strip contain bare soil or dead vegetation which reduces its aesthetic value and could be negatively affecting its stormwater treatment function]]
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==Tips to Preserve Basic BMP Function==
*Because the risk of compaction is higher when topsoil is saturated, any maintenance tasks involving vehicle (e.g., ride mower) or foot traffic on the filter bed should not be performed during wet weather.
*Use push mower to maintain enhanced swales with [[grasses]] as [[vegetation]] cover or the lightest ride mower equipment available to minimize compaction of the filter bed.
*Use a mulching mower to maintain enhanced swales with grass as vegetation cover or leave clippings on the surface to help replenish organic matter and nutrients in the topsoil.
*Pruning of mature [[trees]] should be performed under the guidance of a Certified Arborist.
*Woody vegetation should not be planted or allowed to become established where snow will be piled/stored during winter.
*Removal of sediment accumulated on the filter bed surface should be performed by hand with rake and shovel, or vacuum equipment where feasible. If a small excavator is the chosen method, keep the excavator off the BMP footprint to avoid damage to side slopes/embankments and compaction of the [[topsoil]].
==Rehabilitation & Repair==
Table below provides guidance on rehabilitation and repair work specific to enhanced grass swales organized according to BMP component.
[[File:Outlet covered swale.PNG|330px|thumb|link=https://sustainabletechnologies.ca/app/uploads/2018/02/Enhanced-Swales-Fact-Sheet.pdf|An example of an outlet in an enhanced swale requiring maintenance to remove built up debris and sediment. <ref>TRCA. 2018. Inspection and Maintenance of Stormwater Best Management Practices - Enhanced Swales. Fact Sheet. https://sustainabletechnologies.ca/app/uploads/2018/02/Enhanced-Swales-Fact-Sheet.pdf</ref>]]
{|{| class="wikitable" style="width:900px;"
|+'''Enhanced Swales: Key Components, Typical Issues and Rehabilitation Requirements'''
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!Component
!Problem
!Rehabilitation Tasks
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|'''[[Inlets]]'''
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Inlets are producing concentrated flow and causing filter bed erosion
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*Add [[Level spreaders|flow spreading device]] or re-grade existing device back to level. Rake to regrade damaged portion of the filter bed and replant. If problem persists, replace some [[vegetation|plant]] cover with [[stone]].
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| rowspan="3"|'''[[Swales: Construction|Filter Bed]]'''
|Local or average sediment accumulation ≥ 5 cm in depth.
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*At [[inlets]] remove [[stone]] and use vacuum equipment or rake and shovel to remove sediment. For large areas or BMPs, use of a small excavator may be preferable. Restore grades with planting soil that meets design specifications. Test surface infiltration rate to confirm it is > 15 mm/h. Replace [[stone]] and [[vegetation]] coverage (re-use/transplant where possible). If problem persists, add [[pretreatment]] device(s) or investigate the source(s).
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|Surface ponding remains for > 48 hours or surface infiltration rate is < 15 mm/h.
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*Remove sediment as described above. Core aerate (for grass swales); or remove [[stone]], sediment and [[vegetation|plant]] cover and till 5 cm of yard waste compost into the exposed planting [[Soil groups|soil]] to a depth of 20 cm; or remove and replace the uppermost 15 cm of material with planting soil that meets design specifications. Test [[Infiltration: Testing|surface infiltration rate]] to confirm it has been restored to > 15 mm/h. Replace stone and plants (re-use/transplant where possible).
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|Damage to filter bed or slide slope is present (e.g., [[erosion]] rills, animal burrows, sink holes, ruts)
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*Regrade damaged portion by raking and replant or restore [[stone]] cover. Animal burrows, sink holes and compacted areas should be tilled to 20 cm depth prior to re-grading. If problems persist, consider adding [[Level spreaders|flow spreading device]] to prevent [[erosion]] or barriers to discourage foot or vehicular traffic.
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|'''[[Vegetation]]'''
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Plants not thriving and planting soil is low in organic matter (<5%) or available [[Nutrients|phosphorus]] (<12 mg/kg)
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*Remove [[stone]] and [[vegetation|plant]] cover and uppermost 5 cm of planting soil, spread 5 cm of yard waste compost, incorporate into [[Soil groups|soil]] to 20 cm depth by tilling. Replace stone and plants (re-use/transplant where possible).
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