Plymouth Harbor Dredging to Begin Next Month

Maintenance dredging of the Plymouth Harbor Federal navigation project in Plymouth, Massachusetts, is set to begin this November and will take about 5 to 6 months to complete, according to the U.S. Army Corps of Engineers, New England District.

The Army Corps recently awarded this $9,375,800.00 contract to Burnham Associates, Inc., of Salem, Mass.

“Natural shoaling processes have reduced available depths to as little as 7.0 feet in the 18-foot main channel (which is maintained to 15.0 feet), 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, Massachusetts. “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 and maintained dimensions.”

Plymouth Harbor is located in Plymouth Bay, about 18 miles north of the Cape Cod Canal. It is partially protected by Long Beach, a 3.6-mile long barrier beach that extends along the harbor’s east side.

Initial work in the harbor, completed in 1893, involved dredging a channel in the inner harbor and a basin in front of the town wharf, both to a depth of nine feet. Work also included protecting Long Beach from erosion to prevent further damage to the harbor.

The 18-foot mean lower low water (MLLW) outer 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.

USACE expects construction to take between 5-6 months within the allowable dredge window of Oct. 1 to Jan. 31 of any given year. If dredging is not completed in one season, construction will occur the following season within the allowable dredge window.

The dredging project will be managed by the Corps under the supervision of a Corps’ Quality Assurance Representative to assure compliance with contract requirements.