A dual-chamber bioswale was constructed and tested over three years to evaluate the ability of green infrastructure to manage stormwater runoff and chemical contaminants. The bioswale effectively infiltrated over 99% of stormwater inputs and significantly reduced levels of atrazine, nitrate, and phosphate through the soil amendment BioMix Osorb. Plant growth was 15% greater in the chamber with the amended soil. Overall, the results indicate that augmenting soil with amendments designed to treat contaminants can improve stormwater management performance and support larger plant biomass.

1. Three
Years
of
Full
Scale
Testing
an
Advanced
Bioswale
Green
infrastructure
is
to
manage
stormwater
through
on-­‐site
capture
and
infiltration.
The
ability
of
low
impact
designs
to
manage
chemical
contaminants
was
characterized
to
provide
data
for
engineering
calculations.
BioMix
Osorb®
was
evaluated
has
a
soil
amendment.
A
dual-­‐chamber
bioswale
allowed
for
comparison
of
standard
and
amended
soil.
A
dual
chamber
full-­‐scale
bioswales
were
constructed
in
June
2011
at
the
College
of
Wooster
retrofitting
an
existing
drainage
basin.
The
bioswale
accepts
water
from
1.9
acres
including
2
parking
lots,
3
housing
units,
and
the
spillage
from
a
roof
of
a
large
multi-­‐purpose
building.
The
dual
chamber
design
allow
comparison
testing
of
soil
amended
with
Iron-­‐Osorb
sorbent.
Various
parameters
were
measured
including
influent
and
effluent
water
quality,
infiltration
rate,
plant
growth,
microbial
populations,
and
maintenance
requirements.
Input
stormwater
was
spiked
with
contaminants
at
intervals
to
measure
effectiveness
of
treatment.
Gas
chromatography
is
used
to
measure
volatile
and
semi-­‐volatile
compounds.
Nutrients
and
plant
mass
was
measured
by
the
STAR
laboratory
at
The
Ohio
State
University.
Infiltration
of
stormwater
was
high
for
the
bioswales
exceeding
99%
in
all
rainfall
events.
Input
water
was
spiked
atrazine,
nitrate,
and
phosphate
and
was
reduced
on
average
99%,
85%,
and
95%,
respectively.
Above
ground
plant
growth
was
15%
greater
in
the
Fe-­‐Osorb
chamber
of
the
bioswale.
Over
the
past
three
years,
a
relatively
compact
bioswale
has
effectively
managed
stormwater
inputs
from
1.9
acres
of
campus
grounds
without
an
incident
of
overflow.
Maintenance
involved
annual
removal
of
plant
mass
in
the
late
Fall
and
general
mowing.
Augmenting
the
soil
with
amendments
specifically
designed
to
treat
chemical
contaminants
improves
performances
and
promotes
a
larger
above
ground
plant
biomass,
presumably
by
removing
bioinhibitory
compounds.