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Inspection and Maintenance: Enhanced Swales (view source)
Revision as of 16:52, 6 July 2022
, 2 years agono edit summary
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==Rehabilitation & Repair==
Table below provides guidance on rehabilitation and repair work specific to bioretention and dry swales organized according to BMP component.
{|{| class="wikitable" style="width: 1000px;"
|+'''Bioretention/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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Inlet is 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 or restore [[mulch]]/[[stone]] cover. If problem persists, replace some mulch cover with stone.
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| rowspan="3"|'''[[Bioretention: Construction checklist|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 filter media that meets design specifications. Test surface infiltration rate (one test for every 25 m2 of filter bed area) to confirm it is > 25 mm/h. Replace [[stone]], [[mulch]] 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 <25 mm/h.
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*Remove sediment as described above. Core aerate (for sodded bioretention); or remove stone, sediment, mulch, and plant cover and till the exposed filter media to a depth of 20 cm; or remove and replace the uppermost 15 cm of material with filter media that meets specifications. Test surface infiltration rate (one test for every 25 m2 of filter bed area) to confirm it is > 25 mm/h. Replace stone, mulch 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 [[mulch]]/[[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 flow spreading device to prevent [[erosion]] or barriers to discourage foot or vehicular traffic.
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|'''[[Vegetation]]'''
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Vegetation is not thriving and filter media is low in organic matter (<3%) or extractable phosphorus (<10 mg/kg)
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*Remove stone, mulch and plant cover and uppermost 5 cm of filter media, spread 5 cm of yard waste compost, incorporate into filter media to 20 cm depth by tilling. Replace stone, mulch and plants (re-use/transplant where possible).
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|'''[[Underdrain|Sub-drain]]'''
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Sub-drain perforated pipe is obstructed by sediment or roots.
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*Schedule hydro-vac truck or drain-snaking service to clear the obstruction.
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[[File:Sediment removal.PNG|500px]]
<br>
Technician conducting sediment removal to ensure infiltration rates for the<br>
practice are able to maintain > 25 mm/h. [https://sustainabletechnologies.ca/app/uploads/2018/02/Bioretention-and-Dry-Swales-Fact-Sheet.pdf Photo Source: TRCA, 2018]<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>