Sediment Movement and Dredging in Newark Bay, NJ

New York Harbor requires dredging to provide adequate navigable depths for commercial shipping. Newark Bay is a major center for maritime activities in the Harbor. Sediment enters Newark Bay from upstream tributaries and downstream channels connected to the open harbor. The recently deposited surficial and suspended sediments in Newark Bay are highly mobile. A well-calibrated and validated three-dimensional mathematical model was used to investigate the movement of these sediments. The numerical simulations predicted that most of the sediments, which are re-suspended from the tidal flats or channel bottoms due to wind or tidal action, are being retained in Newark Bay proper and the lower reaches of the Passaic and Hackensack Rivers. The calculations indicated that bottom sediments can be eroded by flood currents and thereafter tend to resettle in the deepened navigation channels. The accumulated material is approximately equal in mass to the mass removed by the routine maintenance dredging. These sediments have been determined to be unsuitable for ocean placement because of contamination. Dredging has removed a substantial amount of contaminated sediment from the marine environment and placed it in confined sites or used it beneficially on land.