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Line 24: === Key Components, Descriptions and Routine Inspection and Maintenance Tasks ===Line 47:
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Inspection and Maintenance: Bioretention & Bioswales (view source)
Revision as of 19:54, 7 April 2022
, 2 years ago→Key Components, Descriptions and Routine Inspection and Maintenance Tasks
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==Key Components and I&M Tasks==
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|+'''Bioretention/Swales: Key Components, Descriptions and Routine I&M Requriements'''
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!Component
!Component
|'''[[Inlets]]'''
|'''[[Inlets]]'''
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Structures that deliver water to the BMP (e.g., curb-cuts, spillways, pavement edges, catchbasins, pipes).
Structures that deliver water to the BMP (e.g., [[Curb cuts]], [[inlets|spillways]], pavement edges, [[inlets|catch basins]], [[pipes]]).
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*Keep free of obstructions;
*Keep free of obstructions;
*Remove trash, debris and sediment biannually to quarterly;
*Remove trash, debris and sediment biannually to quarterly;
*Measure sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance;
*Measure sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance;
*Remove woody [[vegetation]] from filter bed at [[inlets]] annually.
*Remove woody [[vegetation]] from filter bed at [[inlets]] annually.
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|'''Perimeter'''
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Side slopes or structures that define the BMP footprint; may be covered by a mixture of [[vegetation]], [[mulch]] and [[stone]] with slopes up to 2:1 (H:V), or concrete or masonry structures with vertical walls.
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*Confirm the surface ponding footprint area dimensions are within ±10% of the design and that maximum surface ponding depth meets design specifications;
*Check for side slope erosion or damage that compromises water storage capacity
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|'''[[Bioretention: Construction checklist|Filter Bed]]'''
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Flat or gently sloping area composed of a 0.5 to 1 m deep layer of [[filter media]] [[soil]] covered by a mixture of [[vegetation]], [[mulch]] and [[stone]] where [[Bioretention: TTT|surface ponding]] and filtration of runoff occurs.
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*Check for standing water, barren/eroded areas, sinkholes or animal burrows;
*Remove trash biannually to quarterly;
*Rake regularly to redistribute [[mulch]] and prevent sediment crusts;
*Maintain 5 to 10 cm of mulch or stone cover to prevent weed growth and soil [[erosion]];
*Repair sunken areas when ≥ 10 cm deep and barren/eroded areas when ≥ 30 cm long;
*Remove sediment when > 5 cm deep or time to drain water ponded on the surface exceeds 48 hours.
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|'''[[Vegetation]]'''
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A mixture of deep rooting perennial plants, tolerant to both wet and dry conditions and salt (if receiving pavement runoff); can include grasses, flowers, shrubs and trees; roots uptake water and return it to the atmosphere; provide habitat for organisms that break down trapped pollutants and help maintain soil structure and permeability.
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*Routine maintenance is the same as a conventional perennial garden bed;
*In the first 2 months water plantings frequently (biweekly in the absence or rain) and as needed (e.g., bimonthly) over the remainder of the first growing season;
*Remove weeds and undesirable plants biannually to quarterly;
*Replace dead plantings annually to achieve 80% cover by the third growing season;
*Do not apply chemical fertilizers.
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|'''[[Overflow|Overflow Outlet]]'''
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Structures that convey overflows to another BMP or municipal storm sewer.
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*Keep free of obstructions;
*Remove trash, debris and sediment biannually to quarterly.
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|'''[[Underdrain|Sub-drain]]'''
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Optional component; [[Pipes|perforated pipe(s)]] surrounded by [[gravel]] and may be wrapped in [[Geotextile|geotextile filter fabric]]; installed below the [[filter media]] [[soil]] layer to collect and convey treated water to an adjacent drainage system; may also include a flow restrictor.
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*Include [[Bioretention: Sizing|standpipes]] or access points to provide means of flushing the [[perforated pipe]];
*Keep pipe and flow restrictor free of obstructions by flushing annually;
*Inspect flow restrictor frequently (e.g., biannually to quarterly).
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|'''[[Monitoring well]]'''
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[[Wells|Perforated standpipe]] that extends from the bottom of the BMP to above the invert of the [[Overflow|overflow outlet]]. Allows [[Digital technologies|measurement of subsurface water level]] to track drainage performance over time.
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*[[Wells|Standpipes]] should be securely capped on both ends and remain undamaged.
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==References==
==References==