michael brock, p.e. · 2015. 1. 5. · sheet flow special considerations •application of runoff...
TRANSCRIPT
![Page 1: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/1.jpg)
6 ‐ Introduction to Green Infrastructure Practices
Michael Brock, P.E.
![Page 2: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/2.jpg)
Module Content
GeneralOverviewIntrinsicGreenInfrastructurePracticesStructuralGreenInfrastructurePractices
![Page 3: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/3.jpg)
Introduction
GreenInfrastructurePracticesEcosystem‐basedapproachesthatstrategicallyintegratesstormwater controlsthroughouttheurban/rurallandscapetoachievethedesired site
runoffquantityandquality.
(GIPs)
![Page 4: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/4.jpg)
Green Infrastructure Practices (GIPs)
Intendedtomimicthenaturalhydrologicconditionandallowstormwater toinfiltrateintotheground,evaporateintotheair,evapotranspirate byplantuptakeorcapturedforreuse.
Designedtomeetmultiplestormwater managementobjectives,includingreductionsinrunoffvolume,peakflowratereductions,andwaterqualityprotection.
Decentralizedstormwater managementstrategiesofmultiplesmall,localizedcontrolsthatmaybecombinedintoa“treatmenttrain”toprovidecomprehensivestormwater treatment.
Constructedindividually,oraspartoflargerconstructionprojects.
![Page 5: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/5.jpg)
Green Infrastructure Practices (GIPs)
SelectionofEffectiveGIPs
![Page 6: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/6.jpg)
Green Infrastructure Practices (GIPs)
![Page 7: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/7.jpg)
Green Infrastructure Practices (GIPs)
ApplicationtoSiteDesign• Duringthedesignprocess,intrinsicGIPsareappliedtothesitefirstandthen,ifrequired,structuralGIPsareapplied.
• RunoffReductionCredit(RRCredit),Level1(L1)andLevel2(L2),areappliedbasedonthephysicaldesignoftheGIP.
GOALWeightedRv <0.20
![Page 8: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/8.jpg)
Green Infrastructure Practices (GIPs)
![Page 9: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/9.jpg)
Intrinsic GIPs Overview
GeneralConsiderations• Takeadvantageofand/orenhancetheabilityofexistingpervious,naturalorlandscape,surfacestoreduceandtreatstormwater run‐off.
GIPsDisconnectedDownspouts
SheetFlowReforestation
(less design, more landscaping)
![Page 10: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/10.jpg)
Downspout Disconnection
Source: www.lowimpactdevelopment.org
![Page 11: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/11.jpg)
Downspout Disconnection
Roofdownspoutsaredisconnectedfromdirectflowintosewerinletsorimperviousareas(driveways,parkinglots,roads)leadingdirectlyintoapublicstormwater system.
RunoffisredirectedtoadownstreamperviousareasorotherGIPs.
![Page 12: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/12.jpg)
Downspout Disconnection
Methods• Simple– disconnectandroutetoperviousarea• Series– leadstoadownstreamGIP
Source:VADCR,2011
![Page 13: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/13.jpg)
Downspout Disconnection
Performance• Runoffisslowedandgivenmoreopportunitytoforinfiltration,evapotranspiration andrainwaterharvesting/reuse.
• RRCredit:Level1=25%;Level2=50%(usedwithotherGIPs).
SpecialConsiderations• TypicallyrequiresperviousareaequaltoorgreaterthantheimperviousCDA.
• Usuallyinvolvesperiodiclawnorlandscapingmaintenanceinthefilterpath,unlessdirectedtorainbarreloranatural,undisturbedsetting.
![Page 14: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/14.jpg)
Downspout Disconnection
RooftopDisconnection– SectionView:SimpleDisconnectiontodownstreamBioretention (Source:VADCR,2011)
![Page 15: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/15.jpg)
Downspout Disconnection
AmendedFilterPathtoDownstreamGrassChannel,orothertreatment(Source:VADCR,2011)
![Page 16: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/16.jpg)
Sheet Flow
![Page 17: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/17.jpg)
Sheet Flow
Imperviousareasaredisconnectedandrunoffisdirectedthroughalevelspreadercreatingsheetflowontoanadjacentperviousarea.
Twobasicvariations:• Conservedopenspace• Vegetatedfilterstrip
![Page 18: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/18.jpg)
Sheet Flow
Conservedopenspace
![Page 19: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/19.jpg)
Sheet Flow
Vegetatedfilterstrip
![Page 20: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/20.jpg)
Sheet Flow
Performance• Soilbasedsystem• Imperviouscontributative drainagearea~5,000sf(maximum)
• Runofftobeslowed,redirectedandtogivemoreopportunitytoforinfiltration,andsedimentremovalofrunoff.
• Varydependingontheunderlyingsoilpermeability.• RRCredit:Level1– 50%;Level2– 75%(Soildependant)
![Page 21: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/21.jpg)
Sheet Flow
SpecialConsiderations• Applicationofrunoffreductioncreditdependantonmeetingappropriateminimumdesigncriteria.
• Sheetflowandhydraulicconnectivitymustbemaintained.
• Levelspreader(vegetated,graveldiaphragm,permeableberm,engineeredstructure)isanintegralpartoftheGIPfunction.
• Usuallyinvolvesperiodicmaintenanceoflevelspreaderandlandscapingmaintenanceofvegetatedfilterstriporconservedopenspace.
![Page 22: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/22.jpg)
Sheet Flow
LevelSpreader
![Page 23: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/23.jpg)
Sheet Flow
LevelSpreader
![Page 24: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/24.jpg)
Reforestation
![Page 25: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/25.jpg)
Reforestation
Reforestationrefersto(primarily)treesplantedingroupsinurbanareassuchas:parkinglots,rightofways(ROW),parks,schools,publiclands,vacantland,andneighborhoodopenspaces.
Providesshade,stormwater retentionandaddsthesitesaestheticvalue.
Theexplicitgoalistoestablishamatureforestcanopythatwillinterceptrainfall,increaseevapotranspiration,andenhancesoilinfiltrationrates.
![Page 26: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/26.jpg)
Reforestation
Performance• Soilbasedsystem.•Minimumareasize~5,000sf (contiguous)• ReforestedareaRv basedonHSGsoiltypeandamendment.
• Additionalrunoffreductioncreditavailableifusedasvegetatedfilterstripforsheetflow.
• RRCredit:(Soildependant) Level1;90%‐ 96%(noamendedsoils) Level2;95%‐ 98%(withamendedsoils)
![Page 27: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/27.jpg)
Reforestation
SpecialConsiderations• Usuallyrequireslargededicatedareatoprovidefortreegrowthandforsignificantreductioninstormwaterrunoff.
• Vegetation(tree)selection.
![Page 28: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/28.jpg)
Structural GIPs Overview
Engineeredpracticesthataredesigned,constructedandmaintainedtofacilitateinfiltration,evaporation,evapotranspiration ofstormwaterrunoffandrainwaterharvestingforreuse.GeneralConsiderations
• Soils(HSG/Infiltrationrates/Plantingrequirements).
• ImperviousContributingDrainageArea.• Depthtowatertableorbedrock.• Existingpollution
![Page 29: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/29.jpg)
Structural GIPs Overview
GIPsBioretention Urban
BioretentionWaterQuality
SwaleGreenRoof
GrassChannel Cistern
PermeablePavements
InfiltrationTrench
ExtendedDetention(more design, less landscaping)
![Page 30: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/30.jpg)
Bioretention
![Page 31: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/31.jpg)
Bioretention
Vegetated,shallowdepressions.Capturedrunoffistreatedbyfiltrationthroughanengineeredsoilmedium,andistheneitherinfiltratedintothesubsoilorexfiltrated throughanunderdrain.Primarycomponentisthefilterbed,whichhasamixtureofsand,soilandorganicmaterial(filteringmedia)withasurfacemulchlayer.Onasmallerscalethesearepopularlyknowas“RainGardens”.Variations
• Withoutunderdrains,subsoils withinfiltrationrategreaterthan½”perhour
• Withunderdrains,subsoils withinfiltrationratelessthan½”perhour
![Page 32: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/32.jpg)
Bioretention
Performance• Soilfiltration/gravelbasedstorage/infiltrationsystem.
• ImperviousCDA~2.5acres,multiplecellscanservelargerareas.
• Goodenvironmentforrunoffreduction,filtration,biologicaluptake,andmicrobialactivity,andprovideshighpollutantremoval.
• Canbecomeanattractivelandscapingfeaturewithhighamenityvalueandcommunityacceptance.
• Performancelevelsbasedonfiltermediadepth.• RRCredit:Level1– 60%;Level2– 80%
![Page 33: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/33.jpg)
Bioretention
SpecialConsiderations• Pre‐treatmentrequiredtoremovecoursesediments.• Canbeinstalled: Online,mustprovideforoverflow Offline,alternateflowwhenfull
• Ingeneral,vegetativegoalistoachievesurfaceareacoverageofatleast75%.
• Forabioretention areatoqualifyforL2design,aminimumofonetreemustbeplantedforevery400squarefeet.
• Onceestablished,typicalonlyspringcleanupmaintenance.
![Page 34: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/34.jpg)
Bioretention
Source:VADCR,2010
![Page 35: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/35.jpg)
Bioretention
Source:VADCR,2011
![Page 36: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/36.jpg)
Bioretention
Source:VA‐DCR,2013
![Page 37: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/37.jpg)
Bioretention
Source:VA‐DCR,2013
![Page 38: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/38.jpg)
Bioretention
Source:VA‐DCR,2013
![Page 39: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/39.jpg)
Urban Bioretention
![Page 40: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/40.jpg)
Urban Bioretention
UrbanBioretention issimilartotraditionalbioretentionpractices,butisfitintohard‐sidedcontainerswithinurbanlandscapessuchasplanterboxesortreeplanters.
Capturedrunoffistreatedbyfiltrationthroughanengineeredsoilmedium,andistheneitherinfiltratedintothesubsoilorexfiltrated throughanunderdrain.
Primaryuseisforsmallfragmenteddrainageareasandfeature“hardedges”.
Variations:• Stormwater planters– betweenbuildings,sidewalksandroadways• GreenStreets– roadsidesandmedians
![Page 41: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/41.jpg)
Urban Bioretention
Performance• Soilfiltration/gravelbasedstorage/infiltrationsystem• ImperviousCDA~2,500sf (maximum)• UrbanBioretention createsagoodenvironmentforrunoffreduction,filtration,biologicaluptake,andmicrobialactivity,andprovideshighpollutantremoval.UrbanBioretention canbecomeanattractivelandscapingfeaturewithhighamenityvalueandcommunityacceptance.
• RRCredit:Level1– 60%
![Page 42: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/42.jpg)
Urban Bioretention
SpecialConsiderations• SmallimperviousCDA.• Usuallyrequiresflowdiversionandunderdrain withconnectionstolocalstormwater system.
• Protectionofadjacentbuildingfoundationsandlocationofoverheadandundergroundutilities.
• Considervisualobstructions,utilitiesandmaintenanceforplantingschosen.
•Maintenance Landscapeandtrashremoval. Mayrequireirrigationduringperiodsofdrought.
![Page 43: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/43.jpg)
Urban Bioretention
![Page 44: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/44.jpg)
Water Quality Swale
![Page 45: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/45.jpg)
Water Quality Swale
Vegetatedopenchannelsdesignedtocaptureandinfiltratestormwater runoffwithinadrystoragelayerbeneaththebaseofthechannel.Swalesareessentiallybioretention cellsthatareshallower,configuredaslinearchannels.Canbeplantedwithturfgrass,tallmeadowgrasses,decorativeherbaceouscoverortrees.Swaleisasoilfiltersystemthattemporarilystoresandthenfiltersthedesiredtreatmentvolume.ConveyancechanneltodownstreamGIP.Variations:
• Withoutunderdrains,subsoils withinfiltrationrategreaterthan½”perhour
• Withunderdrains,subsoils withinfiltrationratelessthan½”perhour
![Page 46: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/46.jpg)
Water Quality Swale
Performance• Soilfiltration/gravelbasedstorage/infiltrationsystem.
• ImperviousCDA~2.5acres• Primarypollutantremovalmechanismsoperatinginswalesaresettling,filteringinfiltrationandplantuptake.
• RRCredit:Level1– 40%;Level2– 60%
![Page 47: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/47.jpg)
Water Quality Swale
SpecialConsiderations• Runoffacceptancecanbeeitherlongitudinalorlateral.• Slopeslessthan2%orprovidecheckdamstoslowchannelvelocities.
• Underdrains mayberequiredwithHSGC&HSGDsoils.•Multiplevariationsingeometrytofitexistingsitetopography
•Maintenance Landscapeandtrashremoval. Onceestablished,typicalonlyspringcleanup.
![Page 48: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/48.jpg)
Water Quality Swale
![Page 49: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/49.jpg)
Water Quality Swale
Storage/ Infiltration without Underdrain
Storage/ Infiltration with Underdrain
With Underdrain
Source:VADCR,2011
![Page 50: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/50.jpg)
Grass Channel
![Page 51: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/51.jpg)
Grass Channel
Conveyancechannelsthataredesignedtoprovidesometreatmentofrunoff,aswellastoslowdownrunoffvelocitiesfortreatmentbyotherdownstreamGIPs.
Appropriateforanumberofapplicationsincludingtreatingrunofffrompavedroadsandotherimperviousareas.
Limitedapplicationstructuralcontrolintendedforsmalldrainageareas.
Apreferablealternativetobothcurbandgutterstormwater conveyance,wheredevelopmentdensity,topographyandsoilspermit.
![Page 52: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/52.jpg)
Grass Channel
Performance• Soilbasedsystem.• ImperviousCDA~5acres• Channelsthatarevegetatedandaredesignedtofilterstormwater runoffthroughsettlingandbiologicaluptakemechanisms,aswellastoslowwaterfortreatmentbyanotherstructuralcontrol.
• Varydependingontheunderlyingsoilpermeability.• RRCredit:Level1– 10%,20%;Level2– 20%,30%(Soildependant)
![Page 53: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/53.jpg)
Grass Channel
SpecialConsiderations• Slopeslessthan2%orprovidecheckdamstoslowchannelvelocities.
• HSGC&HSGDsoilsshouldbeamendedtoimproveperformance.
• Grassesshouldbeseeded(notsodded)toprovide90%turf(thick,dense)coverage.
• Grassesshouldbefloodanddroughttolerant.Maintenance
• Maintaingrassheightof3to4inches.• Removalofsedimentbuildupinchannelbottomwhenitaccumulatesto25%oforiginaltotalchannelvolume.
• Ensurethatrillsandgullieshavenotformedonsideslopes.• Removetrashanddebrisbuildup.• Replantareaswherevegetationhasnotbeensuccessfullyestablished.
• Onceestablished,springcleanup.
![Page 54: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/54.jpg)
Grass Channel
![Page 55: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/55.jpg)
Grass Channel
![Page 56: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/56.jpg)
Grass Channel
![Page 57: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/57.jpg)
Permeable Pavements
![Page 58: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/58.jpg)
Permeable Pavements
Allowstormwater runofftofilterthroughvoidsinthepavementsurfaceintoanunderlyingstonereservoir,whereitistemporarilystoredand/orinfiltrated.Severaldesignvariants,butallhaveasimilarstructure,consistingofasurfacepavementlayer,anunderlyingstoneaggregatereservoirlayerandafilterlayerorfabricinstalledonthebottom.MajorCategories:
• Modularblocksystems• Perviousconcrete• PorousAsphalt• Grassandgravel
![Page 59: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/59.jpg)
Permeable Pavements
Performance• Gravelbasedstorage/infiltrationsystem.• Designgoalistomaximizerunoffreduction(Tv capture).• RRCredit: Level1;45%(allowedtohandleuptotwiceimperviousCDA) Level2;75%(onlyallowedhandlingrainfallonitssurface)
SpecialConsiderations• Underdrain requiredifsubsoilinfiltrationratelessthan½”perhour.
• PrimelocationsonHSGAandHSGBsoils.• Sensitivetohighsedimentanddebris(trashloading).• Sensitivetotrafficloads(shearstresses).
Maintenance• Usuallyinvolvesvacuumsweepingofpavementsurfaces.
![Page 60: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/60.jpg)
Permeable Pavements
![Page 61: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/61.jpg)
Infiltration Trench
![Page 62: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/62.jpg)
Infiltration Trench
Trenchesareexcavationstypicallyfilledwithstone(#57)tocreateanundergroundreservoirforstormwater runoff.
Runoffvolumegraduallyexfiltrates throughthebottomandsidesofthetrenchintothesubsoils andoveraperiodoftimeeventualreachingthewatertable.
Bydivertingrunoffintothesoil,thetrenchnotonlytreatsthewaterqualityvolume,butalsohelpstopreservethenaturalwaterbalanceonasiteandcanrechargegroundwater,preservingthebaseflow.
Limitedtoareaswithhighlyporoussoilswherethewatertableand/orbedrockarelocatedwellbelowthebottomofthetrench.
![Page 63: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/63.jpg)
Infiltration Trench
Performance• Gravelbasestorage,soilbasedinfiltration.• ImperviousCDA~2.5acres•Widevarietyofpollutantsfromstormwater throughabsorption,precipitation,filtering,andbacterialandchemicaldegradation.
• RRCredit:Level1– 50%;Level2– 90%SpecialConsiderations
• Sedimentloadandothersuspendedsolidsshouldberemovedfromrunoffbypretreatmentmeasures.
• On‐lineandoff‐lineapplications.• Requiresinfiltrationratesgreaterthan½”perhour.• Notapplicableforrunofffrompollutionhotspots.
![Page 64: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/64.jpg)
Infiltration Trench
Maintenance• Ensurethatcontributingareaandinletsareclearofdebris.• Removesedimentandoil/greasefrompretreatmentandoverflowdevices.
• Checkobservationwellsfollowing3daysofdryweather.Failuretopercolateindicatesclogging.
• Removetreesthatstarttogrowinthevicinityofthetrench.
• Replacepeagravel/topsoilandtopsurfacefilterfabric(whenclogged).
![Page 65: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/65.jpg)
Infiltration Trench
![Page 66: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/66.jpg)
Green Roof
![Page 67: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/67.jpg)
Green Roof
Arealternativeroofsurfacesthattypicallyconsistofwaterproofinganddrainagematerialandanengineeredgrowingmediathatisdesignedtosupportplantgrowth(alsoknownasvegetatedroofs,livingroofsorecoroofs).Captureandtemporarilystorestormwater runoffinthegrowingmediabeforeitisconveyedintothestormdrainsystem.Aportionofthecapturedstormwater evaporatesoristakenupbyplants(evapotranspiration),reducingrunoffvolumes,peakrunoffandpollutantloads.TwoTypes:
• Extensive• Intensive– deepergrowingmedia
![Page 68: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/68.jpg)
Green Roof
![Page 69: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/69.jpg)
Green Roof
![Page 70: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/70.jpg)
Green Roof
Performance• Capture/engineeredgrowthmediainfiltration.• Roofarea(maximum)withnon‐vegetatedareas<20%.• Primarilyrunoffreductionbyevaporationandplantuptake.
• RRCredit:Level1– 80%;Level2– 90%Maintenance
• Handweedingandfertilizing.• Plantreplacement.• Roofleakrepair.
![Page 71: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/71.jpg)
Green Roof
SpecialConsiderations• AlldesignsmustbeinconformancetoASTM(2005)InternationalGreen(Vegetated)RoofStandards.
• Designsmaybelimitedtoroofstructuralcapacityandaccess.• Plantselectionforvegetatedrooftopsisanintegraldesignconsideration,whichisgovernedbylocalclimateanddesignobjectives.Theprimarygroundcoverformostvegetatedroofinstallationsisahardy,low‐growingsucculentsthatarematchedtothelocalclimateconditionsandcantoleratethedifficultgrowingconditions(sunlight,drought,saturatedsoil).
• Requirementforirrigationduringperiodsofdrought.• Protectionfrombuildingmaintenanceactivities,particularlyinvolvingcleaning(overspray)ofchemicalagents.
![Page 72: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/72.jpg)
Green Roof
![Page 73: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/73.jpg)
Cistern
![Page 74: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/74.jpg)
Cistern
Raintanksandcisternsareusedtointercept,divert,storeandreleaserainfallingonrooftopsforfutureuse.Twomethods:
• Aboveground• Belowground
![Page 75: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/75.jpg)
Cistern
Performance• Captureandnon‐potablewaterreuse.• Capturevolumebasedonstorage(tank)capacity.Capacityisprimarilybasedonanticipateddemand,roofareaandrainfall.
• Primarilybasedondedicatedreusedemand.• RRCredit:Variableupto90%reduction(treatmentvolume).
SpecialConsiderations• SteepterrainapplicationwhereotherGIPsarenotappropriate.
• Varioussystemdesignconfigurations: Yearroundindoorusewithoptionalseasonaloutdooruse. Seasonaloutdooruseandoptionalyear‐roundsecondaryrunoffreductionpractice. Year‐roundindooruse,seasonaloutdoorirrigation,andnon‐seasonaltreatmentinasecondaryrunoffreductionpractice.
![Page 76: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/76.jpg)
Cistern
Maintenance• Inspectedtwiceyearly(spring/fall).• Usuallycleaningoffiltersandsedimentaccumulationinstoragetank(s).
![Page 77: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/77.jpg)
Extended Detention
![Page 78: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/78.jpg)
Extended Detention
Constructedstormwater detentionbasinthathasapermanentpool,ormicropool.Runofffromeachraineventiscapturedandtreatedthroughsettlementofsuspendedsolids.Variations:
•Wetextendeddetention•Micropool extendeddetention.•Multiplepondsystem.
![Page 79: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/79.jpg)
Extended Detention
Performance• Thetemporaryponding enablesparticulatepollutantstosettleoutandreducesthemaximumpeakdischargetothedownstreamchannelreducingtheeffectiveshearstressonthedownstreambanks.
• RRCredit:Level1– 15%Maintenance
• Inspectedannually.• Typicalactivities: Lowfloworificemaintenance(twiceyearly). Removaloftrashandfloatablematerials. Sedimentremoval. Vegetationmaintenance.
![Page 80: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/80.jpg)
Extended Detention
SpecialConsiderations• Designtoachieveaminimumdrawdowntime(24hours),ratherthanpeakflow.
• Accessformaintenanceandinspection.• Emergencyspillwayforlargestormevents.• No‐erosiveinlet/outfallvelocity.• Screeningoflowfloworifices.• Landscapingandplantingplans.•Mosquitoabatement.• TennesseeSafeDamsActmayapplytopondswithstoragevolumesandembankmentheightslargeenoughtofallundertheregulationfordamsafety.
•Multi‐usefunctionality.
![Page 81: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/81.jpg)
Extended Detention
![Page 82: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/82.jpg)
Extended Detention
![Page 83: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/83.jpg)
Module Topic Summary
GeneralOverviewIntrinsicGreenInfrastructurePractices
• Key:Takingadvantageofexistingnaturallandscape.StructuralGreenInfrastructurePractices
• Key:
![Page 84: Michael Brock, P.E. · 2015. 1. 5. · Sheet Flow Special Considerations •Application of runoff reduction credit dependant on meeting appropriate minimum design criteria. •Sheet](https://reader036.vdocument.in/reader036/viewer/2022081618/60a3ea659c532216292605cf/html5/thumbnails/84.jpg)
Questions?