USA: Charlestown Seeks Corps Permit to Dredge Ninigret Pond
The town of Charlestown is seeking a permit from the U.S. Army Corps of Engineers, New England District for work in waters of the United States to dredge Ninigret Pond and place the material in the intertidal zone to nourish Charlestown Beach in Charlestown, Rhode Island.
The town of Charlestown is proposing to perform maintenance and new hydraulic dredging with the material beneficially reused as beach nourishment. The work is proposed in the Ninigret Pond Sedimentation Basin, Relief Channel and Secondary Sedimentation Basin. The dredged material will be deposited in the intertidal zone on Charlestown Beach.
The maintenance dredging of the sedimentation basin and relief channel are a component of the Ninigret and Cross Mills Pond Habitat Restoration Project. That project was funded and conducted by the Corps of Engineers and the state of Rhode Island from 2006 – 2008. Work on that project included dredging 122,000 cubic yards of material from the Charlestown Breachway, 75,000 cubic yards from the sedimentation basin and relief channel, and the restoration of approximately 40 acres of eelgrass habitat.
In addition to maintenance dredging the sedimentation basin and relief channel, the town proposes new dredging to create a secondary sedimentation basin further within Ninigret Pond. There is an issue with the sedimentation basin and relief channel filling up with sediments faster than anticipated and it was determined that a secondary sedimentation basin is necessary. The project purpose is to maintain navigational access to Ninigret Pond for boaters and to maintain the Ninigret and Cross Mills Pond Habitat Restoration Project.
Sediment will be removed to a depth of -8 feet below mean low water in the sedimentation basin for an estimated 59,000 cubic yards of material. Sediment will be removed from the relief channel to a depth of -4.5 feet below mean low water for an estimated 16,345 cubic yards of material. The secondary sedimentation basin will be created in the southerly portion of the relief channel with an approximate area of 3.88 acres.
Sediment will be removed to a depth of -8 feet below mean low water for an estimated 28,175 cubic yards of material.
The total estimated volume of sediment to be dredged per dredging event from the sedimentation basin, relief basin and secondary sedimentation basin is approximately 100,000 cubic yards of material. All dredging will be hydraulic dredging with the material piped approximately 4,500 feet east to Charlestown Breachway to a 1,200-linear-foot section of Charlestown Beach. The material will be pumped into the intertidal zone where it will naturally be washed up on the shore and become beach nourishment.
The dredging portion of this project will impact approximately 12.14 acres of Essential Fish Habitat for various species and life stages. Habitat at this site can be described as sands and silts. Loss of this habitat may adversely affect some of these species. However, the Corps has made a preliminary determination that the site-specific adverse effect will not be substantial. Further consultation with the National Marine Fisheries Service regarding Essential Fish Habitat conservation recommendations is being conducted and will be concluded prior to the final permit decision.
Press Release, September 12, 2012