Cocheco River Dredge

The City of Dover and Public Service of New Hampshire (PSNH) are teaming up to conduct the dredging project to remove sediment as part of the cleanup of the former Dover Manufactured Gas Plant (MGP) site and to improve navigation in Dover Landing. This dredging work will be conducted in conjunction with the maintenance dredging of the Cochecho River channel by the City and the US Army Corps of Engineers (USACE).

Project Area

The channel maintenance dredge will be performed immediately downstream from Dover Landing and involve the lower approximately three miles of the Cochecho River above its confluence with the Piscataqua River. The PSNH-funded Dover Landing dredge and the federally-funded maintenance dredging projects are critical components of the City’s long term economic development plan for its waterfront. The dredging projects will improve both environmental conditions and navigation in the river.

History

In August 2000, the New Hampshire Department of Environmental Services (NHDES) approved a waiver of State Solid Waste rules requested by the City for construction of a cell to receive dredge spoils from the maintenance dredge project. USACE estimated that approximately 65,000 cubic yards of sediment from the channel dredging project would be placed in the cell.

In August, 2003, NHDES approved a waiver request to place approximately 19,000 cubic yards of sediment from the Dover Landing dredge in the cell.

The Dredge

The dredged sediment will be placed in a cell located on City-owned property to the east of the former Department of Public Works (DPW) facility on River Street. Dredging is planned to begin during the next available dredge window, which is from 15 November 2004 to 15 March 2005. Wetlands approvals have been issued by the NHDES Wetlands Bureau for both dredging projects.

The disposal cell will be constructed to receive the dredge spoil material (river sediment) generated during dredging activities. The dredge material will be placed into a lined disposal cell that will be constructed prior to initiation of dredging activities. The dredge material will be graded and capped at the end of the project. The disposal cell will receive only river sediment generated during the aforementioned Dover Landing and maintenance dredging projects. The disposal cell will be designed to accommodate only the type and volume of material to be generated during the dredging projects and will not be used for other solid waste disposal purposes. If feasible, the City plans to use the top of the disposal cell for secondary (recreation) use.

Sediments dredged from the central channel of the Cochecho River and Dover Landing will be off-loaded onto water-tight trucks at the north end of the City of Dover former DPW property located on River Street. The dredged sediment will be transported across the former DPW facility property directly to the spoils cell. The project will include the development of a dredge spoil management plan that will include measures to limit potential impacts to the City property during transport of the sediment.

The Future

The disposal cell will be constructed during the late fall of 2003 and spring of 2004, if necessary. The disposal cell will be closed and capped following completion of the dredging projects and dewatering of the dredged sediments placed in the cell. The City will be responsible for long-term maintenance of the cell.

Both the Dover Landing and the maintenance dredging project are important components of the City’s current waterfront revitalization master plan. The City, PSNH and USACE are committed to completing the Dover Landing and Cochecho River maintenance dredging projects in an efficient and timely manner with as little disruption as possible to local neighbors and businesses.