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Inspection and Maintenance: Enhanced Swales (view source)
Revision as of 13:10, 5 July 2022
, 1 year ago→Routine Maintenance - Key Components and I&M Tasks
*[https://lonepinebooks.com/product/plants-of-southern-ontario-2/ Plants of Southern Ontario (book), 2014, by Richard Dickinson and France Royer, Lone Pine Publishing, 528 pgs.]
*[https://lonepinebooks.com/product/plants-of-southern-ontario-2/ Plants of Southern Ontario (book), 2014, by Richard Dickinson and France Royer, Lone Pine Publishing, 528 pgs.]
*[http://www.agrifs.ir/sites/default/files/Weeds%20of%20North%20America%20%7BRichard%20Dickinson%7D%20%5B9780226076447%5D%20%282014%29_2.pdf Weeds of North America (book), 2014, by Richard Dickinson and France Royer, University of Chicago Press, 656 pgs.]
*[http://www.agrifs.ir/sites/default/files/Weeds%20of%20North%20America%20%7BRichard%20Dickinson%7D%20%5B9780226076447%5D%20%282014%29_2.pdf Weeds of North America (book), 2014, by Richard Dickinson and France Royer, University of Chicago Press, 656 pgs.]
{|class="wikitable" style="width: 1280px"
|+'''Bioretention/Swales: Key Components, Descriptions and Routine I&M Requirements'''
|-
!style="width: 500px"|Component
!style="width: 1500px"|Description
!style="width: 1500px"|Inspection & Maintenance Tasks
!style="width: 500px"|<span style="color:green">('''Pass''')</span> Photo Example
!style="width: 550px"|<span style="color:red">('''Fail''')</span> Photo Example
|-
|'''[[Enhanced Swales|Contributing Drainage Area (CDA)]]'''
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Area(s) from which runoff directed to the BMP originates; includes both impervious and pervious areas.
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*Remove trash, debris and sediment from pavements (biannually to quarterly) and eavestroughs (annually);
*Replant or seed bare soil areas as needed.
|[[File:Pass.PNG|300px|thumb|center|CDA has not changed in size or land cover. Sediment, trash or debris is not accumulating and point sources of contaminants are not visible.]]
|[[File:Fail bio.PNG|280px|thumb|center|Size of the CDA has changed from design assumptions. A point source for contaminants is visible (i.e. lack of sediment controls on adjacent construction site). (Photo Source: North Carolina Cooperative Extension)]]
|-
|'''[[Pretreatment]]'''
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Devices or features that retain trash, debris and sediment; help to extend the [[Cost analysis resources|operating life cycle]]; examples are eavestrough screens, [[Pretreatment|catch basin]] inserts and sumps, [[oil and grit separators]], [[inlets|geotextile-lined inlets]], [[Gravel diaphragms|gravel trenches]], [[Vegetated filter strips|grass filter strips]] and [[forebays]].
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*Remove trash, debris and sediment annually to biannually or when the device sump is half full;
*Measure sediment depth or volume during each cleaning, or annually to estimate accumulation rate and optimize frequency of maintenance
|[[File:Pretreatment pass bio.PNG|310px|thumb|center|[[Forebay]] is free of sediment, trash and debris and recently maintained. The large stones in the feature are used to slow down and spread out inflowing water into the feature and they remain well arranged and in place.]]
|[[File:Pretreatment fail bio.PNG|290px|thumb|center|An erosion gully occurring where bare soil is starting to become visible on the [[Vegetated filter strips|grass filter strip]] pretreatment feature at the inlet, thus indicating it is not effectively slowing and spreading out the inflow of stormwater to the BMP.]]
|-
|'''[[Inlets]] & [[Overflow: Gallery|Overflow Outlets]]'''
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Structures that deliver water to the BMP (e.g., [[Curb cuts]], [[inlets|spillways]], pavement edges, [[inlets|catch basins]], [[pipes]]) or [[Flow control|convey flow]] that exceeds the storage capacity of the BMP to another drainage system (i.e. other LID BMP, or storm sewer).
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*Keep free of obstructions;
*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;
*Remove woody [[vegetation]] from filter bed at [[inlets]] annually.
|[[File:Inlets bio pass.PNG|285px|thumb|center|There is no evidence of damage or displacement of the inlet structure that would prevent runoff from freely entering the BMP.]]
|[[File:Inlets bio fail.PNG|300px|thumb|center|Accumulated sediment and vegetation is preventing stormwater from entering the BMP. Sediment on the pavement surface in front of the inlet indicates ponding is also occurring]]
|-
|'''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 3:1 (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 the maximum surface ponding depth behind [[check dams]] meets design specifications;
*Check for side slope erosion/damage from vehicular/foot traffic.
|[[File:Perimeter bio pass.PNG|305px|thumb|center|The footprint area of the bioretention cell does not significantly deviate from the final design and should not negatively affect its stormwater management treatment performance.]]
|[[File:Perimeter bio fail.PNG|300px|thumb|center|The footprint area of the BMP is significantly smaller than what was specified in the final design of this example and differ greater than the recommended SWM criteria requirements (>10%).]]
|-
|'''[[Enhanced swales: Specifications|Filter Bed]]'''
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Linearly-oriented, gently sloping area (between 0.5 and 4% [[slope]]) where [[Runoff volume control targets|runoff]] is filtered and conveyed; [[Flow in a swale|parabolic or trapezoidal cross-section]], lined with 20 to 30 cm of planting soil and covered with deep rooting perennial [[grasses]] or a mixture of [[vegetation]] and [[stone]].
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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;
*Mow [[grasses]] to maintain height of > 10 cm;
*For sod or [[turf grass|turf grass]] vegetation cover, aerate and dethatch annually to maintain [[Low permeability soils|soil permeability]] and dense grass cover;
*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 behind [[check dams]] exceeds 48 hours.
|[[File:Filter bed bio pass.PNG|295px|thumb|center|There are no erosion gullies or bare soil areas on the filter bed surface and mulch cover remains in place.]]
|[[File:Filter bed bio fail.PNG|300px|thumb|center|Erosion gullies and bare soil areas are present on the filter bed surface, indicating that concentrated flow occurs regularly into the BMP feature. (Photo Source: CVC).]]
|-
|'''[[Vegetation]]'''
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Deep rooting [[perennial]] grasses or a mixture of [[wildflowers]] and [[shrubs]], tolerant to both wet and dry conditions and [[salt]]; 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 lawn;
*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.
|[[File:Vegetation bio pass.PNG|315px|thumb|center|The planted portion of the bioretention cell is completely covered with dense, attractive vegetation which helps to maintain its stormwater treatment function and aesthetic value.]]
|[[File:Vegetation bio fail .PNG|290px|thumb|center|A larger portion of the bioretention cell has no vegetation cover which reduces its aesthetic value and could be negatively affecting its stormwater treatment function. Much less than 80% of the planting area is covered by living vegetation requiring immediate maintenance and reseeding.]]
|-
|}