25 



Table 3-1 Annual Disposal History 



Massachusetts Bay Disposal Site 



Year Disposal Volume 



1985 



72,H4m 3 



1986 



141,895 m 3 



1987 



82,439 m 3 



1988 



94,415 m 3 



1989 



156,803 m 3 



1990 



217,081 m 3 



1991 



173,506 m 3 



1992 



194,343 m 3 



material by the barge logs or the failure of 

 the model to take consolidation or 

 dewatering into consideration once the 

 material has been deposited (Wiley 1994). 



3.1.2 Elliott Bay and Port Gardner 



Elliott Bay, located off Seattle, WA 

 and Port Gardner, located at Everett, WA 

 are two nondispersive sites used in the 

 Puget Sound Dredged Disposal Analysis 

 (PSDDA) Program (Revelas et al. 1991). 

 Water depths exceed 132 m (440') at Port 

 Gardner and 108 m (360') at Elliott Bay. 

 Both sites were monitored after the 

 1989/1990 disposal season to determine if 

 the dredged material was located within 

 the designated site boundaries. 



At Elliott Bay, 100,000 m 3 of dredged 

 material were released within a 183 m 

 radius target zone at the center of the site. 

 A REMOTS® survey was conducted which 

 included stations within the boundary of 

 the disposal site and in the perimeter (a 

 buffer zone surrounding the disposal site). 

 The survey showed that dredged material 

 distribution mirrored the shape of the 



disposal site boundary with no evidence of 

 dredged material in any of the perimeter 

 stations (Figure 3-7). At Port Gardner, 

 approximately 762,000 m 3 of dredged 

 material were released in the winter of 

 1989/1990. As at Elliott Bay, barges were 

 allowed to open their doors in a 183 m 

 radius target zone at the center of the site. 

 The REMOTS® survey at Port Gardner 

 showed dredged material at all stations 

 within the boundary and eight stations 

 outside the boundary (Figure 3-8). Prior 

 to disposal, Port Gardner was modeled 

 using the DIFID (Disposal From 

 Instantaneous Dump) model from the US 

 Army Engineer Waterways Experiment 

 Station (WES) to predict the distribution of 

 dredged material. The model correctly 

 predicted areas of thick deposits but did 

 not predict areas of thin cover to the west 

 (Figure 3-9). The thin cover is >3 cm 

 thick at the perimeter stations. 



Deep Water Capping 



