cold and returned to the NED laboratory, where they were stored 

 at 4°C until analyzed. The parameters measured included grain 

 size, metals (Hg, As, Cd, Cr, Cu, Ni, Pb, Zn) , and several 

 organic constituents (petroleum hydrocarbons, total organic 

 carbon, PCBs, DDTs) . Only the whole cores from ten of the 

 fifteen stations were analyzed for this study. 



Sediment analyses were conducted by the NED chemistry 

 lab using methods described by the U.S. Environmental Protection 

 Agency (Plumb, 1981) . Mercury analysis was performed using acid 

 digestion and cold vapor atomic absorption spectrophotometry; 

 arsenic analysis was accomplished using acid digestion and 

 gaseous anhydride atomic absorption spectrophotometry. The other 

 inorganic compounds (arsenic, lead, zinc, chromium, copper, 

 cadmium and nickel) were analyzed using acid digestion and flame 

 atomic absorption spectrophotometry. 



Total organic carbon analyses were conducted with an 

 autoanalyzer using a combustion technigue. Oil and grease 

 measurements were made by extracting the sediment with freon and 

 then analyzing the freon by infrared spectrophotometry. PCBs and 

 DDTs were extracted with hexane and also analyzed by electron 

 capture gas chromatography. 



3 . RESULTS 



3 . 1 Bathymetry 



Examination of the contoured bathymetric chart (Figure 

 3-1) indicates that the disposal point is located in a slight 

 trough running NW-SE. Depths reach more than 9 meters in the 

 center of the survey area and rise to approximately 89.5 to the 

 northeast and 87.5 meters to the southwest. Bathymetry was 

 unable to detect a distinct bell-shape disposal mound (such as 

 those usually formed at shallower sites) as a result of the 

 recent disposal operations. Because no previous bathymetric 

 survey was conducted over the area using the same lane spacing, 

 volume difference calculations were not possible. 



3.2 REMOTS® Sediment Profiling 



The distribution and thickness of dredged material as 

 determined from REMOTS® images reflects the presence of the 

 material deposited at the "DGD" buoy since November, 1985 (Figure 

 3-2). The overall spatial distribution of dredged material 

 extends to the following limits: between 400 and 500 meters 

 south of center, 400 to 500 meters west of center, 500 to 600 

 meters east of center, and as far north of center as surveyed 

 (700 meters) . This dispersion pattern is essentially the same as 

 that mapped in the January 198 6 REMOTS® survey of this area. 

 Several REMOTS® stations extended beyond the eastern, western, 



