Sustaining the economic viability of New York City’s maritime businesses depends upon maintaining the depths of navigation channels, approach channels, and berths at marine terminals and marinas. Dredging to provide deep enough water for vessels to transit safely into, out of, and around New York Harbor has been taking place since the early nineteenth century.
While New York Harbor is a superb natural harbor sheltering vessels from the elements, it is naturally only twenty feet deep. Today’s massive container ships require depths of fifty feet making dredging as vital as paving highways.
Dredging involves the removal of sediments usually by means of a barge-borne crane fitted with a large clam-shell bucket. The material removed include sediments that continuously settle through natural erosion processes and urban runoff. Dredged material management includes both the removal of excess sediment and the management of its placement.
Within the New York Harbor, sediment can consist of different geological types including sand and gravel, silt and clay and glacial till and rock. Sometimes sediments can become contaminated through the absorption of spilled chemicals and heavy metals in the waterways, creating challenges for the management of dredged material.
Contamination of dredged sediment ranges on a continuum, with some material being very clean and some being polluted with various wastes. The more contaminated the sediment is, the more limited the options for management and the more costly management becomes.
While historically material dredged from port areas see relatively higher levels of contamination, much of dredged material within the New York Harbor can be reused beneficially in ways that are both safe and environmentally protective. Some examples of the diverse ways in which dredged material has been used include landfill and brownfield reclamation, habitat restoration, construction materials, and beach replenishment.
After the practice of ocean dumping of dredged material ended in the mid-1990s, the need to identify innovative ways to beneficially reuse dredged material became an economic priority. NYCEDC, working with the Department of Environmental Protection, completed a pilot project at the Pennsylvania and Fountain Avenue Landfills in Brooklyn.
The pilot project successfully demonstrated that dredged material when mixed with Portland Cement, could serve as a good “contour layer” as part of the landfill's closure. This led to a partnership between NYCEDC and the Department of Sanitation allowing large-scale application at Fresh Kills Landfill in Staten Island.
By December 2009, NYCEDC successfully completed the placement of nearly one million cubic yards of processed dredged material at Fresh Kills Landfill. The dredged material was generated by NYCEDC projects, projects around the region, as well as from the Army Corps of Engineer’s Harbor Deepening Project and was made possible through a Beneficial Use Determination (BUD) issued by the New York State Department of Environmental Conservation (NYSDEC). The BUD allowed dredged material to be mixed with cement and placed as a below the liner alternate grading material.
Beginning in 2010, Fresh Kills Landfill will gradually transform into a 2,200-acre public park (nearly three times the size of Central Park) to be enjoyed by New York City residents and visitors alike.
The use of processed dredged material in closing Fresh Kills Landfill resulted in numerous additional benefits to New York City. New York taxpayers saved over $40,000 with the use of dredged material instead of conventional fill. Efficiently transporting this material by barge instead of trucks resulted in significant reductions in air pollution and diesel engine emissions by eliminating approximately 82,000 truck trips from local streets and roads.
NYCEDC continues to work towards making dredging economical for New York’s maritime businesses while also finding viable placement sites for its beneficial reuse.