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: Stormwater

Runoff from impervious surfaces
 17 streams and rivers in VT
impaired by stormwater
 UVM’s 5 new treatment ponds
 Centralized treatment –
undersized? over-worked?
Centralized Stormwater Treatment

Reduces rate of
runoff for selected
design storms
 Fails to control
volume of runoff
 Water quality
treatment???
 Commonly no
recharge to
groundwater
Decentralized Approaches

Small-scale approach
 Treat close to source
 Encourage infiltration,
evapotranspiration
 Examples:
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Filter/buffer strips
Bioswales
Infiltration trenches
Permeable pavement
Roofgardens
THE PROJECT

Design for
demonstration project
 Votey parking lot,
4820 m2 drainage
area, 85% TIA
 Stormwater
monitoring data


Lead and trace metals
2 Fall storm events
Mission & Goals

Minimize the ecological footprint
 Increase environmental consciousness
 “Greening the campus”
 Promote excellence in environmental academics
Decentralized Practices
 Bioretention
 Dry
Wells
 Filter Strips
 Swales
 Rain Barrels
 Cisterns
 Infiltration Trenches
 Tree Box Filter
Bioretention

Landscaped areas
 Conditioned soil
 Detains and infiltrates
 Components:
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Pretreatment area
Ponding area
Ground cover
Planting soil
Plants
Inlet and outlet controls
Dry Wells & Infiltration Trenches
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Excavated trenches
Backfill with stone or gravel
Detains and infiltrates
Components:
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Pretreatment - filtering
Backfill material
Filter fabric lining
Inflow and outflow controls
Observation well
Filter Strips

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Grassy vegetation between runoff source and receiving
waterbody
Level spreader for sheet flow
Components:

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Flow distribution
Planting material
• Berm
• Outlet Controls
Swales


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Dry or wet swales to slow runoff and promote
infiltration
Typical along roadways
Components

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Pretreatment
Check dams
Underdrain
• Planting material
• Conditioned soil
Rain Barrels & Cisterns

Small-scale, low-cost
devices
 Detention and re-use
 Above or below ground
 Components:
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Screen or filter
Container
Sighting gauge
Inlet, outlet, overflow
Tree Box Filters

In-ground containers
with street trees
 Detains, infiltrates,
evapotranspirates
 Components:
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Open-bottom vault
Porous soil media
Underdrain
Salt- and watertolerant trees
CONSTRAINTS
 Physical
Characteristics of Site
 Cost
 Maintenance
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Requirements