BSLA Fieldbook BSLA 2014 Fall Fieldbook | Page 78

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 76 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.