PARENT SESSION
Oral Session # 91: Biogeography III: Aquatic Communities.
Presiding: B Taylor
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 103.
Constructed Spartina planters in Manhattan's East River.
Felson, Alexander*,1, Smith, Ken1, 1 Ken Smith Landscape Architecture, New York, New York, USA
ABSTRACT- Contemporary landscape architect Ken Smith has designed a new small-scale experimental salt-water marsh for Manhattan's East River. The project is quite unusual for the urban island, exemplifying a collaborative approach between high design, aesthetics and functional marsh creation. In the design, saltwater grasses (Spartina alterniflora) fill eight 10'x15' wood planter boxes, which are elevated above the river on a typical I-beam pier structure. Ideally, Spartina would be planted within the tidal zone, but today, with riverbanks converted to vertical walls and ocean-going boats creating severe wakes, the River is inhospitable to vegetative growth. The wetland is raised above mean high water to escape damaging river conditions. Grasses grow out of 18" of sand mixed with organic compost (15%), with a bottom layer of sand and hydrogel (to act as the underlying mud layer preventing drying out of the root structure, especially from wind). Irrigation is the key to the project. Salt water pumped from the still tidal East River and fresh water are both used for irrigation. The combination also functions as an herbicide and flushes out the detritus-accumulating system. Boxes are flooded twice daily to mimic tidal flooding patterns, and because marsh grasses actually grow better in freshwater, city water is used for daily irrigation. Weekly saltwater flooding is used, not for irrigation, but more as an herbicide (deterring invading plant species), and to provide nutrients and larvae including blue crab and mussels, and minerals to the wetland environment. Renewable energy (through on site land or water turbines) provides electricity to run an exposed pump drawing 2,000 cubic feet of water/hour from the East River to flood the boxes. The saltwater pump is flexible, and although initially, for Smith's design, the planter is flooded once a week, it could occur more or less often for experimentation and maintenance purposes.
Key words: Urban, Spartina alterniflora, Marsh, East River