196,874 m 3 have been deposited at the "DGD" buoy since November, 

 1985; given the area of the seafloor covered with dredged 

 material as detected by REMOTS® technology, the entire volume 

 deposited can be accounted for if one assumes an average 

 thickness of 27 cm for those areas around, the disposal point 

 where the dredged material exceeded the prism penetration limits. 



The fact that mean apparent RPD depths have not changed 

 at the disposal area between surveys is not surprising, because 

 disposal operations have been occurring steadily up to the time 

 of each REMOTS® survey. The difference in RPD depths between the 

 disposal area and Reference Station is due to the frequency of 

 disturbance from disposal operations, the shallower depth of 

 bioturbation on the dredged material, and possibly because of 

 higher BOD and COD in the dredged materials. 



The major change in OSI values detected between last 

 year's survey and the present survey at the disposal area is the 

 appearance of negative values in the 1987 data set. This is 

 attributed to the appearance of reducing sediments and poorly 

 colonized dredged material at Station 200S and 300S (Figures 3-7 

 and 3-8) . Even though the OSI for Station 100N cannot be 

 calculated because it is not possible to evaluate the RPD depth 

 for this station, this location appears to be devoid of 

 colonizing benthos and apparently has a relatively low index 

 value as well. 



4 . 3 Sediment Characterization 



The sediment chemistry data collected were analyzed 

 with the intent of finding unique compound ratios that could be 

 used for specifically detecting the GE/Blue Circle sediment in 

 future sampling efforts. If characteristic ratios were 

 identified, results of sediment chemical analyses from sampling 

 after capping could be used to study the effectiveness of the 

 capping operation. For example, chemical analyses conducted on 

 the Saugus River/General Electric material before dredging 

 indicated relatively high PCB (ranging from below detection to 

 3.0 ppm) but low copper (60-93 ppm) concentrations. Therefore, 

 if this relation was also found at the disposal site, the 

 PCB/copper ratio would have been potentially useful in 

 identifying this material. 



The data presented in Table 3-1, however, shows that 

 the PCB concentration is not very high at the disposal area 

 (<0.02 - 0.30 ppm). The measured concentrations are about a 

 factor of ten lower than those measured at the site of dredging. 

 The concentrations of PCBs and copper are both similar to those 

 that have been measured on other dredged materials at FADS (SAIC, 

 1986b) ; therefore, this ratio is both different from that found 

 in the material at the dredge site and also not unique as far as 

 previous measurements made at the disposal site. 



