of contaminated material was the result of 

 project phasing; the more contaminated 

 material was dredged and deposited first 

 and covered by progressively less 

 contaminated, cleaner sediments. Whether 

 this "de facto" approach was a success 

 remained unknown. The 1979 NED 

 project at the Central Long Island Sound 

 Disposal Site (CLIS) made capping 

 procedures formal. Specifications in the 

 dredging plans required that the 

 contaminated sediment from the harbor of 

 Stamford, Connecticut, be capped with 

 cleaner material dredged from the entrance 

 channel of New Haven, Connecticut. 



As a result of the operational success 

 of the 1979 Stamford-New Haven project, 

 controlled, or planned, capping became an 

 important component of the management 

 of open-water disposal sites and is used 

 with increasing frequency in New 

 England. Many capping projects have 

 been performed within the NED's CLIS, 

 New London, and Portland Disposal Sites 

 under the DAMOS Program. Other Corps 

 districts have completed capping projects, 

 such as those at the Mud Dump site in 

 New York (Mansky 1984) and in the 

 Duwamish Waterway in Seattle, 

 Washington (Sumeri 1984a, 1984b). 

 Capping has also been used at several sites 

 in western Europe and in Japan (Shields 

 and Montgomery 1984) and proposed for 

 use in an experimental project where 

 existing submarine borrow pits were to be 

 used as receiving sites for contaminated 

 dredged material (Bokuniewicz 1983). 



1.5 Monitoring of Capped Mounds 



When capping was first proposed, the 

 NED, following the recommendations of 

 several environmental groups, formed a 

 Scientific Advisory Committee (SAC) to 

 review project plans, to make 

 recommendations regarding operational 

 procedures, and to detail requirements 

 associated with both short- and long-term 

 monitoring. The Committee suggested 

 that the proposed capping be viewed as an 

 experiment. Further, they advised that the 

 effectiveness of the capping operations 

 should be verified by in situ monitoring. 



The majority of the capping projects 

 contained a field monitoring component. 

 In New England, field observations of cap 

 integrity and evaluations of the success of 

 disposal protocols have been collected as 

 part of the DAMOS Program (e.g., 

 Morton et al. 1984a). In each of the other 

 capping projects conducted outside New 

 England, special monitoring programs 

 were initiated to evaluate both short- and 

 selected long-term effectiveness criteria 

 (O'Connor and O'Connor 1983, Parker 

 and Valente 1987, Truitt 1986). In 

 addition to these field programs, the 

 USACE sponsored several laboratory 

 investigations intended to assist in 

 determining the optimal cap thickness and 

 the effectiveness of various sediment 

 layers as barriers inhibiting contaminant 

 migration (Gunnison 1984, Brannon et al. 

 1984, 1985, 1986, 1987). 



Fourteen years of monitoring capped 

 mounds in New England have provided a 

 data set of sufficient duration to permit 



Sediment Capping of Subaqueous Dredged Material Disposal Mounds 



