Results from this calculation determined that to detect 

 this level of difference in sediment samples analyzed for 

 chromium required 2 replicates; arsenic, copper, and zinc, 4; 

 lead, mercury, and total organic carbon, 10; PCBs, 12; and 

 petroleum hydrocarbons, 15. Because only 10 sediment samples 

 from the disposal area were analyzed, additional replicates for 

 PCB and petroleum hydrocarbon analyses would be required in order 

 to meet the detection criteria stated above. 



5 . CONCLUSIONS 



The combined data from the bathymetric and REMOTS® 

 surveys suggest that the most recent (November 1985 to February 

 1987) disposal operations produced a relatively thin deposit 

 (i.e., less than 3 cm) on the bottom that is spread over an area 

 with a 500-600 m radius. Although the depth of water (90 m) and 

 the behavior of dredged material during descent have a 

 significant effect on the dispersion of the dredged material on 

 the bottom, disposal operations occurring within a radius of over 

 300 meters (Figure 4-1) could be expected to produce a deposit of 

 dredged material of this morphology. However, until controlled 

 experiments are conducted, the actual effect of either depth or 

 scow locations on the distribution of dredged material on the 

 bottom can not be determined. 



By using REMOTS® technology, estimates of dredged 

 material volume detected at the site showed fair agreement with 

 scow log disposal volumes. The persistence of Stage III infaunal 

 successional assemblages in this area suggest that the 20 - 27 cm 

 layer of deposited material accumulated at a slow rate over the 

 14 months of disposal operations and that there were no quantum 

 inputs of sediment thick enough to eliminate the larger deposit 

 feeders. REMOTS® criteria suggest that the material from the 

 most recent operations (GE and Blue Circle) is located at 

 Stations 100N, CTR, 100E, 200S, and 300S. Material from the Blue 

 Circle dredging operation (overconsolidated mud clasts) is most 

 likely present at 100N and possibly 100E. Medium sand from the 

 Saugus River (GE disposal operation) project may be present at 

 Station 100E. The balance of material at the above stations 

 consists of fine-grained, reducing sediments. 



The results of sediment chemistry analyses showed that 

 sufficient replicates were analyzed to detect differences among 

 sediment samples at an 80% level of precision for all 

 contaminants measured with the exception of PCBs and total 

 petroleum hydrocarbons. The concentrations of most parameters 

 measured in sediment from the disposal area were generally low. 

 In particular, PCB concentrations were considerably lower than 

 expected and would probably not be useful as tracers of this 

 material. Examination of the chemical data from the FADS 



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