shore erosion tend to produce a shoaling effect by filling creeks, rivers, and bays with 

 deposits of sand, silt, or clay. In order to create or maintain adequate depths for large 

 transport ships and protect the economic viability of a port, some namral sediments must 

 be mechanically removed, or dredged, from ship chaimels, anchorage areas, and docking 

 facilities. 



Dredging operations in New England waters typically involve the use of a clamshell 

 bucket to extract rock, sand, gravel, mud, and clay from the bottom of waterways and 

 transfer the materials to barges or on-shore facilities for disposal (Figure 1-1). A number 

 of disposal alternatives exist for dredged material, but the majority of these materials are 

 transported to open water and deposited at predefined dredged material disposal sites. To 

 efficiently manage the large volumes of dredged sediments, the New England District 

 (NAE) of the U.S. Army Corps of Engineers has taken a broad, programmatic approach to 

 dredged material management. 



The dredged material management process is a multi-step decision process 

 incorporating project evaluation, disposal compliance inspections, monitoring, mitigation, 

 and enforcement. The Disposal Area Monitoring System (DAMOS) Program is a critical 

 part of this process, concerned with the long-term monitoring of open water dredged 

 material disposal sites. Established in 1977, the DAMOS Program investigates and 

 minimizes any adverse physical, biological, or chemical impacts of dredging or dredged 

 material disposal. The cooperative efforts of NAE, scientists, and ocean engineers have 

 resulted in the development and implementation of a flexible, tiered management approach 

 used to achieve the goals of the DAMOS Program. 



Before dredging operations begin, the proposed project sediments are sampled and 

 tested to determine their physical and chemical properties. Sediments originating from 

 most of coastal New England are found to have low to undetectable contaminant levels and 

 are considered suitable for unconfined open water disposal. This material can be readily 

 deposited into subaqueous disposal sites or used for a number of beneficial projects (i.e., 

 beach nourishment, marsh and island creation, landfill for development projects). 

 However, since the 1978/79 disposal season, the value of these sediments as capping 

 dredged material (CDM) has been fully realized by the DAMOS Program (Fredette 1994). 



1.3 Subaqueous Capping 



Maintenance or improvement dredging operations conducted in urbanized or 

 industrialized regions tend to yield sediments that contain a variety of environmental 

 contaminants associated with anthropogenic activity. Sediment deposits dredged from 

 industrialized coastlines may contain chemicals that have a potential for adverse environmental 

 impact (i.e., heavy metals, PCBs, and other organic compounds). If found in sufficient 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



