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Treatment of Urban
Water Runoff
Biofiltration using a
Bioswale
Robert Ryan
UC Santa Barbara
11/30/04
Bioswales
 What
 How
is a Bioswale and why use one?
a Bioswale Works
 Results
of Bioswale usage
 Benefits
of Bioswale use and the
Alternatives
What is a Bioswale?
Figure 1.1 [bren study]
Why Use a Bioswale?
Ecologically sound treatment of
runoff. Includes:
Hydrocarbons
Heavy
Metals
Sediment
Nutrients
And many more possibilities
Would otherwise pollute
downstream water ecosystems
Figure 1.2 [bren study]
How a Bioswale Operates
Figure 1.3 [bren study]

Channels runoff from
assigned watershed

Dimensions critical to
efficient operation

Heavy volume flow is
diverted
How a Bioswale Operates, continued
Figure 1.4 [bren study]

Water enters forebay
of Bioswale

Water enters backbay

Sediments settle

Phytoremediation
occurs

Output exits outlet
pipe into natural or
constructed waterway
Phytoremediation
Using plants to remove, transfer, or stabilize,
contaminants in soil, sediment, and groundwater.

Breakdown in soil, or
accumulation in shoots
and leaves

Certain plants for certain
contaminants

Broad application (TNT)
Figure 1.5 [soil.edu]
Results of Bioswale Use

Dramatic reduction of sediments


Lower flow velocities
Reduction of hydrocarbons, nutrients, and metals

EPA studies of Superfund sites: 30-70% decreases

Mature plants more efficient at removal

Efficiency increases with size of Bioswale

High volume flow decreases efficiency
Additional Benefits and Alternatives

Benefits:





Ecological Preservation
Flood control
Aesthetic Value
Inexpensive in comparison
Alternatives


Stormceptor (Costly)
FossilFilter (high maintenance)
Conclusion
 Bioswales
meet increasing demand for
mitigation measures to stop pollution from
urban environments
 Bioswales


work
Sedimentation
Phytoremediation