New Haven & Norwalk Harbor Maintenance Dredging
The New Haven Harbor is an inlet located on the Northern side of the Long Island Sound in Connecticut. Due to the retreat of the glaciers during the last ice age, this inlet was sculpted. The Norwalk Harbor is a recreational boating and commercial harbor that gets its shape from the reach of the Norwalk River, stretching 20 miles south from Wall Street to the Long Island Sound.
CASHMAN was contracted by the Army Corps to conduct maintenance dredging of ~810,000 cubic yards of sediment from the 35-foot channel and 35-foot turning basin in New Haven Harbor, and ~150,000 cubic yards of sediment from the 12-foot channel in Norwalk Harbor.
- Dredged material was removed using a mechanical dredge and scows.
- Disposal was at the Central Long Island Sound Disposal Site (CLISDS), about 6 miles south from New Haven Harbor and about 35 miles east from Norwalk Harbor.
- Dredging and disposal windows were from October 1 to January 31 for Norwalk, and October 1 to April 30 for New Haven.
- At least 110,000 cubic yards of New Haven sediment were reserved for the capping of the Norwalk sediment at the CLISDS.
- CASHMAN'S use of a multibeam-type surveying method for daily quality control surveying was considered a key factor in completing the dredging by limiting any shoals from the soft sediments in the anchorage area.