BSLA
/ TOOLBOX
ABOVE
MassDOT Illustration
A si gn i f i cant o p p o r t u ni ty
exis t s for land s c a p e a r c h i t e c t s
to in t e grat e p ri nc i p l e s o f
p hy t ot e chn o l o g y fo r so i l s a nd
grou n dwat e r i nt o d a i l y d e si g n
p rac t i ce .
m problem that was decades in the making. Plantbased cleanup methods can be as little as 3% of
the cost of traditional cleanup costs (Glass, 1999),
however may take ten years or even decades to reach
cleanup goals. If phytotechnology time frames can
be integrated into long-term planning projects, land
redevelopment could move beyond conventional,
high-cost, single outcome remediation practices that
have limited site design potential beyond treatment.
A significant opportunity exists for landscape
architects to integrate principles of phytotechnology
for soils and groundwater into daily design
practice. As our profession has aptly done with
stormwater filtration, water cleansing, and water
recycling, we can integrate the latest science into
projects by knowing when to invite experts to a
team. One example: Massachusetts Department of
Transportation (MassDOT) Phytotechnology Proejct,
River Street and Western Ave Bridges, Boston, MA
Phytotechnology Team: Offshoots, Inc., Sand
Creek Consultants, & Environmental Consulting
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BSLA
and Technology (ECT), Inc, MassDOT has taken an
important step forward in controlling contaminants
entering into the Charles River Watershed from
adjacent roadways and bridges. Vegetated swales,
constructed wetlands, and other stormwater controls
are being added as critical landscape components
of planned roadway and bridge design projects.
However, what can be done when the stormwater
mitigation site selected was formerly a gas station
or manufactured gas production site with heavy
petroleum contamination? At the River Street and
Western Ave Bridge projects along the Charles
River in Boston, two stormwater sites selected
are impacted with PAHs (Polycyclic Aromatic
Hydrocarbons—a difficult-to-break-down subset
of petroleum products) associated with these
former uses. Typically, a client would just bury this
contamination, cap it, put a use limitation on the site
and wipe their hands clean of the project. MassDOT
instead asked if there was any way to slowly clean
up the soils while treating stormwater runoff at
the same time? Offshoots, Sand Cr eek Consultants
and ECT, Inc. devised a strategy using contrasting
willow, cottonwood and deep rooted grass species to
mound and treat the existing soils on site over time,
while creating a series of natural water cleansing
systems (sedimentation ponds, vegetated swales, and
retention basins) to weave new stormwater through
the site and remove excessive levels of phosphorus
and nitrogen. The result? A “background” landscape
at a highway interchange that will not only filter
stormwater but will rehabilitate a former brownfield
and bring it back into productive use.
In addition to the remediation of existing
contaminated landscapes, preventative planting
palettes for certain site programs, such as
railway corridors, dry cleaners, new industrial
sites, gas stations, parks, and urban homes can
also be created, thus allowing landscape design
to propose vegetation strategies in advance
of future contamination events. In this way
phytotechnologies become projective, anticipatory
and a creative tool for the landscape architect.
The future of phytotechnology is continually
evolving and there is considerable opportunity
for integration with the field of Landscape
Architecture. Designers must work in collaboration
with phytotechnologists to identify synergies and
select appropriate plants to be used in projects
that recognize the need for time on a plant scale.
Ultimately, the success of phytotechnology systems
will depend on our ability as designers to plan
beyond the short term and work hand-in hand with
a multi-disciplinary team to integrate this everevolving field.