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UVM-AWRA CHARRETTE: designing an alternative
stormwater treatment technique
W h a t I s a C h a r r e t t e?
A Charrette is a cross-disciplinary workshop to create designs for complicated problems
in a brief time window.
THE PROBLEM: StormwaterTHE PROBLEM: Stormwater Runoff from impervious surfacesRunoff from impervious surfaces 17 streams and rivers in VT 17 streams and rivers in VT
impaired by stormwaterimpaired by stormwater UVM’s 5 new treatment pondsUVM’s 5 new treatment ponds Centralized treatment – Centralized treatment –
undersized? over-worked?undersized? over-worked?
Centralized Stormwater TreatmentCentralized Stormwater Treatment
Reduces rate of Reduces rate of runoff for selected runoff for selected design stormsdesign storms
Fails to control Fails to control volume of runoffvolume of runoff
Water quality Water quality treatment???treatment???
Commonly no Commonly no recharge to recharge to groundwatergroundwater
Decentralized ApproachesDecentralized Approaches
Small-scale approachSmall-scale approach Treat close to sourceTreat close to source Encourage infiltration, Encourage infiltration,
evapotranspirationevapotranspiration Examples:Examples:
Filter/buffer stripsFilter/buffer strips BioswalesBioswales Infiltration trenchesInfiltration trenches Permeable pavementPermeable pavement RoofgardensRoofgardens
THE PROJECTTHE PROJECT
Design for Design for demonstration projectdemonstration project
Votey parking lot, Votey parking lot, 4820 m4820 m2 2 drainage drainage area, 85% TIAarea, 85% TIA
Stormwater Stormwater monitoring datamonitoring data Lead and trace metalsLead and trace metals 2 Fall storm events2 Fall storm events
Mission & GoalsMission & Goals
Minimize the ecological footprintMinimize the ecological footprint Increase environmental consciousnessIncrease environmental consciousness ““Greening the campus”Greening the campus” Promote excellence in environmental academicsPromote excellence in environmental academics
Decentralized PracticesDecentralized Practices
BioretentionBioretention Dry WellsDry Wells Filter StripsFilter Strips SwalesSwales Rain BarrelsRain Barrels CisternsCisterns Infiltration TrenchesInfiltration Trenches Tree Box FilterTree Box Filter
BioretentionBioretention
Landscaped areasLandscaped areas Conditioned soilConditioned soil Detains and infiltratesDetains and infiltrates Components:Components:
Pretreatment areaPretreatment area Ponding areaPonding area Ground coverGround cover Planting soilPlanting soil PlantsPlants Inlet and outlet controlsInlet and outlet controls
Dry Wells & Infiltration TrenchesDry Wells & Infiltration Trenches
Excavated trenchesExcavated trenches Backfill with stone or gravelBackfill with stone or gravel Detains and infiltratesDetains and infiltrates Components:Components:
Pretreatment - filteringPretreatment - filtering Backfill materialBackfill material Filter fabric liningFilter fabric lining Inflow and outflow controlsInflow and outflow controls Observation wellObservation well
Filter StripsFilter Strips
Grassy vegetation between runoff source and receiving Grassy vegetation between runoff source and receiving waterbodywaterbody
Level spreader for sheet flowLevel spreader for sheet flow Components:Components:
Flow distributionFlow distribution Planting materialPlanting material
• BermBerm• Outlet ControlsOutlet Controls
SwalesSwales Dry or wet swales to slow runoff and promote Dry or wet swales to slow runoff and promote
infiltrationinfiltration Typical along roadways Typical along roadways ComponentsComponents
PretreatmentPretreatment Check damsCheck dams UnderdrainUnderdrain
• Planting materialPlanting material• Conditioned soilConditioned soil
Rain Barrels & CisternsRain Barrels & Cisterns
Small-scale, low-cost Small-scale, low-cost devicesdevices
Detention and re-useDetention and re-use Above or below groundAbove or below ground Components:Components:
Screen or filterScreen or filter ContainerContainer Sighting gaugeSighting gauge Inlet, outlet, overflowInlet, outlet, overflow
Tree Box FiltersTree Box Filters
In-ground containers In-ground containers with street treeswith street trees
Detains, infiltrates, Detains, infiltrates, evapotranspiratesevapotranspirates
Components:Components: Open-bottom vaultOpen-bottom vault Porous soil mediaPorous soil media UnderdrainUnderdrain Salt- and water-Salt- and water-
tolerant treestolerant trees