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Inspection and Maintenance: Bioretention & Bioswales (view source)
Revision as of 15:42, 8 April 2022
, 2 years agono edit summary
*Woody [[vegetation]] should not be planted or allowed to become established where snow will be piled/stored during [[Winter]].
*Woody [[vegetation]] should not be planted or allowed to become established where snow will be piled/stored during [[Winter]].
*Removal of sediment from the filter bed surface should be done with rake and shovel, or vacuum equipment to minimize plant disturbance. If a small excavator is to be used, keep it off the BMP footprint to avoid damage to side slopes/embankments and over-compaction of the [[filter media]].
*Removal of sediment from the filter bed surface should be done with rake and shovel, or vacuum equipment to minimize plant disturbance. If a small excavator is to be used, keep it off the BMP footprint to avoid damage to side slopes/embankments and over-compaction of the [[filter media]].
==Construction Inspection Tasks==
Construction inspections take place during several points in the construction sequence, specific to the type of LID BMP, but at a minimum should be done '''weekly''' and include the following:
# During site preparation, prior to BMP excavation and grading to ensure the CDA is stabilized or that adequate ESCs or flow diversion devices are in place and confirm that construction materials meet design specifications
# At completion of excavation and grading, prior to installation of pipes/sewers and backfilling to ensure depths, slopes and elevations are acceptable
# At completion of installation of pipes/sewers, prior to backfilling to ensure slopes and elevations are acceptable
# After final grading, prior to planting to ensure depths, slopes and elevations are acceptable;
# Prior to hand-off points in the construction sequence when the contractor responsible for the work changes (i.e., hand-offs between the storm sewer servicing, paving, building and landscaping contractors)
# After every large storm event (e.g., 15 mm rainfall depth or greater) to ensure [https://sustainabletechnologies.ca/app/uploads/2020/01/ESC-Guide-for-Urban-Construction_FINAL.pdf Erosion Sediment Controls (ESCs)] and pretreatment or flow diversion devices are functioning and adequately maintained. View the table below, which describes critical points during the construction sequence when inspections should be performed prior to proceeding further.
{|class="wikitable"
|+'''Bioretention/Swales: Construction Inspections'''
|-
!'''Construction Sequence Step & Timing'''
!'''Inspection Item'''
!'''Observations*'''
|-
|'''Site Preparation''' - after site clearing and grading, prior to BMP excavation and grading
|
|rowspan="6"|'''Natural heritage system and tree protection areas remain fenced off'''
|-
ESCs protecting BMP layout area are installed properly
|-
CDA is stabilized or runoff is diverted around BMP layout area
|-
BMP layout area has been cleared and is staked/delineated
|-
Benchmark elevation(s) are established nearby
|-
Construction materials have been confirmed to meet design specifications
|
|-
|'''BMP Excavation and Grading''' - prior to installation of pipes/sewers and backfilling
|
*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.
|-
|'''[[Vegetation]]'''
|
Vegetation is not thriving and filter media is low in organic matter (<3%) or extractable phosphorus (<10 mg/kg)
|
*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).
|-
|'''[[Underdrain|Sub-drain]]'''
|
Sub-drain perforated pipe is obstructed by sediment or roots.
|
*Schedule hydro-vac truck or drain-snaking service to clear the obstruction.
|}
==Routine Maintenance - Key Components and I&M Tasks==
==Routine Maintenance - Key Components and I&M Tasks==