International Dredging Review

International Dredging Review
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On September 26, 2018, Burnham Associates was issued a $9.3 million contract by the U.S. Army Corps of Engineers New England District to complete maintenance dredging of the Plymouth Harbor federal navigation project in Plymouth, Massachusetts. Burnham is using Cashman Dredging and AGM Marine Contractors to get as much work as possible completed before the end of the dredging season January 31.

Burnham is using a fleet of equipment on the project, including the brand-new Thomas Desmond, a 3,000-cubic-yard split hull dump scow with a length of 250-feet and fitted with hydraulic remote controls. The scow barge is teamed with an older barge to carry mud and sand from the harbor. The 40-foot by 30-foot azimuth drive tractor push boat, Mantis, maneuvers the scows. Removing the material is the Samson III mechanical dredge with a 150-ton crane, equipped with 36-inch square and 60-foot long spuds that are raised on hydraulic winches. Its 12-foot bucket can haul 11.5 cubic yards of material. Tug boats Aegean Sea, Kodiak, Grizzly and Baltic Dawn are also on-site.

Natural shoaling reduced depths to as low as 7 feet in the main channel and 4 feet in the anchorage area. Approximately 385,000 cubic yards of sand and silt are being removed from 75 acres. Approximately 41,000 cubic yards of fine sand will be removed from the outer entrance channel and placed at the Green Harbor beach nearshore site, while the remaining material, primarily silt and clay will be placed at the Cape Cod Bay and Massachusetts Bay Disposal sites offshore.

Work will wrap up January 31 for this season and resume October 1. The full project is expected to take between five and six months.