■ Saltwater Herbicide System //
Marsh Planters, East River Ferry Landings, New York City, New York, USA
Pounded by severe wakes from ocean-going boats, the vertical concrete banks of the East River defy traditional riparian restoration tactics. The Marsh Planters do not propose a “restoration”, but present a different strategy, one that balances restoration intentions with the present set of urban forces.
team found that Spartina, cultivated in nurseries, actually grows more successfully in containers submerged in, or irrigated with freshwater. However, brackish water works well as an herbicide, deterring weedy plant species un-adapted to salt-water. Thus the planters undergo two irrigation regimes:
The planters are conceived as a riparian module, an eco-
freshwater for daily irrigation and brackish water on a
Ken Smith Landscape Architect
logical abstraction of the range of plants that occupy
weekly cycle. The brackish East River water is pumped up
the riparian zone. Each planter module is folded to sim-
and sent through exposed channels to flood the boxes
ulate the slope of a natural riverbank, with the inten-
and act as an herbicide.
tion of recreating the physical and hydrological condi-
In addition to working as an herbicide the periodic pumping of brackish water into the constructed marsh also introduces nutrients, minerals, and larvae (invertebrate macrofauna) including fiddler crab, ribbed mussels, and salt marsh snails. This interaction, along with the porous bottom of the steel planters, allows for “a modified land-water interaction” similar to a natural marsh condition. For Ken Smith, the main objective of this design is to allow the irrigation system to be “flexible for both experimental and maintenance issues”. Depending on initial results, East River water could be used exclusively to irrigate the plants, or could be mixed at different concentrations with freshwater. Individual boxes are also controllable, resulting in a simple and easily manipulated system where “smallscale urban experiments” can occur.
tions of low marsh and high marsh. The planters are suspended off a 90ft (27.4m) long pier on a typical I-beam pier structure in order to protect the vegetation from the harsh wakes. Saltwater grasses (Spartina alterniflora) are planted in the eight 10ft x 15ft (3.0m x 4.6m) steel planter boxes. They are planted in a substrate consisting of sand mixed with an organic compost mix and a water-retaining layer of Hydrogel – a super-absorbent polymer, capable of retaining 200 to 400 times its own weight in water. This acts as a replacement for the underlying mud layer found in natural marsh conditions, which prevents the roots from drying out from wind exposure. Despite their common sighting in brackish or saltwater conditions, Ken Smith’s
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