Cashman wraps up Boston Harbor phase two dredging nearly one year ahead of schedule

Cashman Dredging and Marine Contracting of Quincy, Massachusetts, along with joint venture partner The Dutra Group, has completed the second of three phases of the US Army Corps of Engineers’ (USACE) Boston Harbor Navigation Improvement Project nearly one year ahead of schedule.

Beginning in July 2018, the second phase focused on deepening the main ship channels: the Outer Harbor Channel from 12 to 15 metres, the Main Shipping Channel from 12 to 14 metres, and the Reserve Channel from 12 to 14 metres.

Boston Harbor’s Conley Container Terminal, which currently handles 10,000TEU vessels, will now be able to accommodate 12,000 to 14,000TEU vessels calling on the US East Coast, bringing more commerce to the state and region.

The Cashman/Dutra JV removed approximately nine million cubic metres silt, Boston blue clay, glacial till, and weathered rock over an 11-kilometre area using Cashman’s clamshell dredgers Dale Pyatt (pictured) and FJ Belesimo and the backhoe dredger Captain AJ Fournier, as well as Dutra’s clamshell dredger Paula Lee.

Seven split-hull dump scows were used to transport the dredged material to Mass Bay Disposal Site, located approximately 37 kilometres from the project.

To help overcome the hard material in the channel and increase efficiency on the project, Cashman designed and built in-house a new ripper barge and purchased two 25-cubic-metre buckets weighing approximately 36,000 kilograms.

The company also installed its in-house designed scow geofence system (SGS) to add an additional layer of quality control to material disposal via split-hull scow.

The SGS prevents scows from inadvertently opening during loading, maintenance, or transit to the dredged material disposal site. Using a relay to connect the SGS to the programmable logic controller, the scow must be positioned within the predefined area, the geofence, for it to split open and dispose of the material.