Norwalk Harbor Maintenance Dredging Phase I

Norwalk Harbor is a recreational and commercial harbor and seaport at the estuary of the Norwalk River where it flows into Long Island Sound in Norwalk, Connecticut. It is a federal navigation channel of the "recreational and small commercial harbor" variety. 

CASHMAN was contracted by the Army Corps to remove dredged material from the Norwalk River, including material that was contaminated with polyaromatic hydrocarbons (PAHs) and heavy metals. CASHMAN excavated material from the Norwalk River at a rate of 1,500 cubic yards per day. This project was one of the first where CASHMAN constructed a confined aquatic disposal (CAD) cell. CAD cells are increasingly becoming the selected option for the management of unacceptably contaminated sediments. This approach can provide an acceptable compromise when cost, logistics, regulatory acceptance, environmental risk, and perception of various alternatives are considered. 


PROJECT HIGHLIGHTS 

• Approximately 29,000 cubic yards of material were contaminated with polyaromatic hydrocarbons (PAHs) and heavy metals. 
• CASHMAN constructed a confined aquatic disposal (CAD) cell with a template for depositing contaminated material on the project site. 
• Remaining spoils were disposed offshore via bottom dumping scows at the approved Long Island Sound Disposal Site (LISDS). 
• The project was performed under the supervision and regulation of the USACE - New England District and was completed in accordance with all applicable regulations.