Cohasset Dredging Includes Capping
A maintenance and improvement project at a small Massachusetts fishing harbor will include a capping demonstration at the Massachusetts Bay Disposal Site (MBDS.)
Burnham Associates of Salem, Massachusetts was awarded the contract for maintenance and improvement dredging at Cohasset Harbor, Massachusetts on August 3. The company began dredging on September 15 using the Samson 3, a spud barge with backhoe excavator. The contract amount was $1,248,055.
Although suitable for open water disposal without capping, some of the fine-grained sediments from the harbor will be capped with the sandier material from the main anchorage and the entrance channel when disposed at the MBDS. The object of this work is to monitor capping success at the MBDS. The information obtained is expected to aid future decisions on the feasibility and procedures for capping at the MBDS for Cohasset and other projects in Massachusetts.
The project will be complete in January, 1999.
The contract calls for maintenance dredging in the harbor to provide an anchorage area seven feet deep at mean low water (MLW) and 16.3 acres in area; a channel, eight feet deep at MLW and 90 feet wide extending from the anchorage area to the outer harbor; and about 12.4 acres of additional anchorage area, six feet deep at MLW. This includes 3.8 acres in Cohasset Cove, 3.2 acres in the vicinity of Government Island Cove and 5.4 acres in Bailey Creek. A total of 114,500 cubic yards will be dredged.
Cohasset Harbor has not been dredged since the early 1960’s, and the controlling depth had silted to a little as four feet in places, said Murray Mason, Burnham Associates project manager. The harbor is home to about 30 commercial lobster boats, and also has about 300 pleasure boat moorings.
The contract also includes dredging areas outside the federal navigation project for the Town of Cohasset, totaling about 8,000 cubic yards. This additional work will be cost-shared with the Commonwealth of Massachusetts through the Department of Environmental Management.