the mound and the water depth, 19.8 m, may have caused the apex of the mound to 

 be periodically within the wave base, serving as a source for the physical 

 disturbance of these sediments. A dynamic equilibrium between deposition and 

 erosion forces has been shown to exist in Long Island Sound at water depths of 

 approximately 20 m (McCall, 1978). In this site with more exposure to wind and 

 waves from the northeast, this equilibrium depth may be shallower. 



For stations 200E and eastward, changes in OSI value, RPD depth, camera 

 penetration, and grain size indicated conditions typical of the periphery of a 

 disposal mound. Stage III taxa were present, and the OSI value increased to a value 

 of +11 at station 300E and +9 at station 350E. Mean apparent RPD depths and 

 camera penetration values did not return to the ambient conditions of the western 

 end of the transect. These results imply a continued presence of coarse-grained 

 dredged material at these REMOTS® stations with successful recolonization of this 

 material. 



4.2 Springhill Beach Site 



Sediments from the Cape Cod Canal dredging operations also were disposed 

 at the near-shore Springhill Beach Site. Pre-and postdisposal bathymetric surveys 

 were conducted at the Springhill Beach Site to assess the distribution of these 

 newly-deposited sediments. The postdisposal bathymetric survey at the Springhill 

 Beach Site showed several individual mounds resulting from disposal activities. The 

 majority of these mounds occurred on lanes 16 and 19 of the bathymetric survey. 

 These lanes were located approximately 125 - 200 m north of the marker buoys 

 deployed at this site. The depth profile plots for lanes 16 and 19 clearly reflected 

 these subsequent changes in topography (Figure 3-6). 



The depth difference plot did not provide substantial evidence of immediate 

 beach replenishment resulting from the disposal operations. General shoaling and 

 redistribution of sediments around the area of the individual disposal mounds were 

 apparent. One would expect that, given a sufficient amount of time, natural 

 processes (e.g., wave action and long shore currents) might serve to redistribute 

 these sediments along the beach area. Additional bathymetric surveys after a period 

 of time (e.g., six months) could help provide evidence as to whether or not the 

 Springhill Beach Site is serving as a feeder berm for the beach area. 



The volume of accumulated material calculated for the Springhill Beach Site 

 was 82,972 m 3 . Barge disposal logs estimated 87,628 m 5 of material were deposited 

 at the Springhill Beach Site. This fell within the calculated 95% confidence limits 

 (67,736 and 98,200 m s ) and was slightly more than the volume calculated from the 

 successive bathymetric surveys. Typically, the volumes calculated for other disposal 

 sites from successive bathymetric surveys have been significantly less than the barge 

 disposal estimates (e.g., SAIC 1990a, 1990b, 1990c). However, at the Springhill Beach 

 Site, no significant consolidation of sediments would be expected given that the 



Monitoring Cruise at the Cape Cod Canal Disposal Site and Springhill Beach Site 



