USACE Confirms Plans to Dredge Plymouth Harbor

The U.S. Army Corps of Engineers, New England District, has just confirmed its plans to perform maintenance dredging of the Plymouth Harbor Federal navigation project in Plymouth, Mass.

Natural shoaling processes have reduced available depths to as little as 7.0 feet in the 18-foot main channel, 7.0 feet in the 15-foot channel, and 4.0 feet in the 8-foot anchorage, making navigation hazardous at lower stages of the tide,” said Project Manager Michael Walsh, of the Corps’ New England District, Programs/Project Management Division in Concord, Mass. “Maintenance dredging of approximately 385,000 cubic yards of sand and silt from approximately 75 acres of the authorized project area will restore the project to authorized dimensions.”

According to the Corps, the 18-foot mean lower low water (MLLW) entrance channel contains approximately 41,000 cubic yards of fine sand. This material is proposed for placement at the Green Harbor Beach nearshore site dependent upon site capacity. The remaining material (approximately 344,000 cubic yards) is primarily silt and clay and proposed for placement at the Cape Cod Bay and Massachusetts Bay Disposal sites.

Construction is expected to take between 5-6 months within the allowable dredge window of Oct. 1 to Jan. 31 of any given year. The work is currently anticipated to be performed in 2018/2019 or 2019/2020.

USACE also added that if dredging is not completed in one season, construction will occur the following season within the allowable dredge window. The application of this window will limit adverse impacts to federally-listed endangered species and threatened species as well as avoid the eelgrass growing season, anadromous fish migrations, and the spawning of winter flounder and shellfish.

Proposed work is being coordinated with: U.S. Environmental Protection Agency; U.S. Fish and Wildlife Service; National Marine Fisheries Service; Massachusetts Office of Coastal Zone Management; Massachusetts Department of Environmental Protection; Massachusetts Division of Marine Fisheries; Massachusetts Historical Commission; Massachusetts Board of Underwater Archaeological Resources; Mashpee Wampanoag Tribe; Wampanoag Tribe of Gay Head (Aquinnah); Plymouth harbormaster and town Division of Marine and Environmental Affairs.