Mystic River Maintenance Dredging

The Mystic River separates the towns of Stonington and Groton in New London County in southeastern Connecticut and is on Fishers Island Sound, the eastern arm of Long Island Sound. The overall Mystic River Federal Navigation Project consists of a 15-foot channel, 125 feet from the Sound up to the railroad bridge and 100-feet wide up to the U.S. Route 1 bridge; a 12-foot channel above the highway bridge to the upper wharves at the Seaport Museum; a 9-foot x 8.5-acre anchorage in the harbor north of Mason Island; and a 9-ft. turning basin above the railroad bridge. CASHMAN conducted maintenance dredging in those channels. The project required the removal of 159,000 yd³ of material by mechanical dredge from the Federal Channel with the removed material transported by scow and disposed at the New London Disposal Site (located ~5 miles from the mouth of the Mystic River). CASHMAN also was responsible for the removal of ~27,000 yd³ of material by mechanical dredge from the State Channels with disposal at the Central Long Island Sound Disposal Site (located ~35 miles from the mouth of the Mystic River). 


PROJECT HIGHLIGHTS 

• Dredging work was sequenced so that all dredging of the channel above the highway bridge to the upper wharves at the Mystic Seaport Museum was completed prior to dredging in all other areas. 
• CASHMAN DREDGING'S use of a multi-beam type surveying method for daily.
• Quality control surveying was a key factor in completing the dredging by limiting shoals from forming in the soft sediments in the Federal and State Channels and Federal anchorage area. 
• Use of excavators equipped with state-of-the-art, custom bucket positioning software allowed for highly accurate dredging in close proximity to docks and boats, without incident. 
• CASHMAN'S Dredge Quality Management electronic tracking system for the scows operated consistently over the 115 scow disposal events for the dredging of the Federal Channel and 17 scow disposal events from the State Channels. 
• In spite of extreme winter weather where the area experienced severe cold and two blizzards during the month of January 2015, CASHMAN was able to complete the project on time.