EWN Publications

Utilization of Passive and Active Mechanical Dewatering Technologies to Process Navigational Dredged Material on a Small Footprint

W.S. Douglas, W. Henderson, J. Heeren, S. Minnich, and C. Mullan
October 31, 2020

About This Publication

WEDA Journal of Dredging

The Office of Maritime Resources (OMR) of the New Jersey Department of Transportation (NJDOT) is responsible for maintaining 200 nautical miles of shallow draft navigation channels statewide. The Shark River Channel and Spur and Shark River Bay, Monmouth County, New Jersey provide access for recreational and commercial marine traffic including commercial fishing. As is true along much of New Jersey’s coastline, the bay’s densely developed geography has made it very difficult to find a suitable location to manage dredged material. Maintenance dredging of the channels was last authorized by the U.S. Army Corps of Engineers (USACE) in 1985 and considered again in the late 1990s through the 2000s. However, the lack of an operationally sized dewatering space stalled the project for many years while local officials debated solutions. The landfall of Superstorm Sandy in the fall of 2012 caused sand, mud, and silt shoaling that severely impacted navigation and jeopardized the local economy, significantly increasing the pressure to find a solution. In January 2018, the project team completed the hydraulic dredging of 68,417 cubic yards (CY) of sediment from approximately 1.6 miles of the Shark River Channel and Spur. The project depth was 6.0 feet below mean low water, plus 1.0 foot of allowable overdredging. The dredging and dewatering operations occurred in three phases and included both passive (geobags) and active (hydrocyclones and belt filter presses) mechanical dewatering techniques. All sediment was or will be beneficially used for beach replenishment, daily landfill cover, or in a future shoreline stabilization project. This paper will review strategies used for dewatering, specific challenges addressed, costs, and how this project could be replicated for other projects in densely developed areas where traditional management methods are not viable.