Changes

|*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).

|*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.

|Surface ponding remains for >48 hours or surface infiltration rate is <25 mm/h.

|*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).

|*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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|'''[[Vegetation]]'''

|'''[[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.

Vegetation is not thriving and filter media is low in organic matter (<3%) or extractable phosphorus (<10 mg/kg)

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*Routine maintenance is the same as a conventional perennial garden bed;

*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).

*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.  

*Remove trash, debris and sediment biannually to quarterly.

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|'''[[Underdrain|Sub-drain]]'''

|'''[[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.

Sub-drain perforated pipe is obstructed by sediment or roots.

*Include [[Bioretention: Sizing|standpipes]] or access points to provide means of flushing the [[perforated pipe]];

[[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.

*Schedule hydro-vac truck or drain-snaking service to clear the obstruction.

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==References==

==References==