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ability of the cap to isolate dredged 

 material contaminants from overlying 

 waters and biota has been documented 

 over time by observing the recolonization 

 rate of the cap by infauna, analyzing bulk 

 sediment chemistry from surface grab 

 samples as well as vertical core profiles, 

 and measuring contaminant body burden 

 levels from resident infauna. REMOTS® 

 sediment-profile photography has been 

 used to characterize the rate of infaunal 

 recolonization to provide information on 

 the health of the benthic community on the 

 cap (SAIC 1989b). Analyses of bulk 

 sediment chemistry and body burden of 

 infauna have given more detailed 

 information on changes in contaminant 

 levels at capped mounds and their 

 availability to the biotic community. To 

 date, the monitoring of capped mounds has 

 given no indication of any perceived 

 problems. Changes in recolonization rates 

 or increases in containment levels in 

 sediments or infauna would have 

 warranted further investigation to 

 determine the source of contamination 

 (Germano et al. 1994). 



Three examples of effective and one 

 example of ineffective cap coverage can be 

 seen in results from experimental capping 

 operations at CLIS; the mounds capped at 

 CLIS include Stamford-New Haven North 

 (STNH-N), Stamford-New Haven South 

 (STNH-S), Cap Site 1 (CS-1), and Cap 

 Site 2 (CS-2). Both STNH-N and STNH- 

 S mounds were capped successfully due to 

 interim monitoring during the disposal 

 operation and control over the placement 

 of cap material (e.g., Morton 1979, 

 Morton and Miller 1980, SAIC 1984b, 

 Murray et al. 1992). At STNH-N, cap 



material completely covered the peak and 

 flanks of the mound, extending its areal 

 extent as well as its height (Figure 2-1). 

 Cap coverage at STNH-S extended over 

 most of the contaminated material (Figure 

 2-2). At CS-1 and CS-2, a LORAN-C fix 

 was used as a location point for the 

 disposal of cap material, and it was 

 assumed that random error in placement 

 would result in the correct distribution of 

 the cap over the contaminated dredged 

 material. At CS-2, the cap disposal points 

 were concentrated to the west of the 

 mound (Figure 2-3). Because a buoy 

 existed as a stationary reference point, the 

 cap material disposal points were close 

 enough to the mound to cover it 

 adequately. At CS-1 there was no buoy, 

 and the barge operators relied only on 

 LORAN-C coordinates to locate the cap 

 material disposal location. As a result, the 

 cap material at CS-1 was spread southwest 

 of the disposal point by barges passing the 

 release point as they steamed in from the 

 northeast (Figure 2-4; SAIC 1987). These 

 examples illustrate the importance of 

 placement control for the contaminated 

 dredged material and the cleaner cap 

 material. Operational control over 

 dredged material placement must be 

 consistently applied to projects at all water 

 depths to cap contaminated dredged 

 material successfully. 



Deep Water Capping 



