Appendix B: Bioretention systemchecklist /
Table B.15 Design assessment checklist: bioretention systems
Generalinformation
SiteID
Asset ID(s)
Bioretention system location(s) and co-ordinates / Drawingreference(s)
Dateofassessment / Specificationreference(s)
Primaryfunctionofbioretention system / Treatment
Check / MDR / Summarydetails1 / Acceptable(Y/N) / Comments/remedialactions
Dimensions(Section18.2)
Length (m)
Width(m)
Topsurfacearea(m2)
Sideslopes(1in ?)
Depth(m)
Freeboard(m)
Longitudinalslope(1in ?) /
Inflows(Section18.8.1)
Provide a description of thecontributingcatchment
landuseandits size (m2)
Doesthedesign include:
▪a suitable flow spreadingdevice
▪appropriatedropsfromtherunoffsurfaceintothebioretentionsystem
▪appropriateenergy dissipation? /
Outfallarrangements(Section18.8.2)
Provide details of any flow control systems,overflowarrangements (for events greater thanthetreatmentcapacity)and limitingdischargeratefrombioretentionsystem
Isthebioretentionsystem designedtoallow infiltration? If yes, attachinfiltrationassessment
Is a geomembranerequired to prevent infiltration?If yes, give reason
Depth to maximum likely groundwater level (m)
Waterqualitytreatment(Section18.5)
For the 1 year 30 minute eventor water qualitytreatment volume confirm:
Maximumdepthof surfacepondingis 150 mm /
Surfacepondingis fullydraineddownin40–48h /
Depth of filter bed(m) /
Storage(Section18.4)
Designreturnperiod(s) (years)
Maximumdesign water depth(s) and level(s)
Maximumdesignstorage volume(s)(m3)
Landscape/biodiversity(Sections18.6,18.7and18.10)
Doestheproposedplantinghave potential tocreate biodiverse habitats?
Have native plant speciesbeen used? (Note: ifornamentalspecies are proposed, give reasonsand describemeasures that prevent theirmigrationtonaturalwaterbodies)
Istheproposedplantingappropriatetothelocation, visually, relative to gradient, water depthsetcandwithrespecttoaccess andmaintenance?
Where relevant, confirm that plantingdesigndoesnot adverselyimpact highway visibility and safetyrequirements(check withhighway authority)
Istheproposedtopsoilprofilesuitable to sustaintheproposedplant species andas permeableasthe filter bed?
Criticalmaterialsandproductspecifications(Section 18.9)
Geomembrane
Geotextile(non-woven)
Mulchlayer
Filtermedium
Transition layer
Drainagelayer
Other(includingproprietarysystems):
Constructability(Section18.11)
Arethereanyidentifiableconstruction risks? If yes,state and confirmacceptableriskmanagementmeasures are proposed
Maintainability(Section18.12)
Confirm that accessformaintenanceisacceptable andsummarisedetails
Aretherespecific features that are likely to posemaintenancedifficulties? If yes, identifymitigationmeasuresrequired
Bioretentiondesignacceptability / Summarydetailsincludinganychangesrequired / Acceptable (Y/N) / Datechangesmade
Acceptable:
Minorchanges required:
Majorchangesrequired/redesign:
Note
1Ifthereis an MDR(asindicated)confirmwhetherornotthisis met andprovidedetails of any variations.
1