20 



Twenty REMOTS® stations were surveyed in both January and July. In July, 

 fourteen remained dredged material, four remained ambient sediment, one (B2) was ambient 

 and became covered with dredged material, and one (G2) was ambient in January, but the 

 camera did not penetrate the sediment in July (Figure 3-5). In general, penetration depths 

 were shallower for ambient sediment than dredged material. 



In January, the dredged material boundary was undefmed at the north central point 

 and to the east and south. REMOTS® Station EO was surveyed in July, and dredged material 

 was detected, extending the undefmed boundary to the north. Stations J3, J5, K4, and J6 

 were chosen in July to determine the extent of the dredged material boundary to the east. 

 Ambient sediment was detected at these stations and more clearly defmed the eastern 

 boundary of the dredged material. Additional stations to the south (J8, D9, F9, 19, BIO, 

 E10, H10, J10, Cll, Kll, E12, and G12) all exhibited dredged material, leaving the 

 southern boundary undefined. These stations are near the location of the disposal buoy from 

 1979 to 1984 (43°34.110' N, 70°01.910' W). Stations K9, M9, 17, and N10 were water or 

 surface photos, providing no clear information. 



Parameters that indicate the health of the benthic environment in the REMOTS® 

 photographs include the Redox Potential Discontinuity (RPD) depth and the successional 

 stage. The multiparameter REMOTS® Organism-Sediment Index (OSI) is used to 

 characterize habitat disturbance. The parameters used to calculate the OSI values are the 

 mean apparent RPD depth, the presence of methane or low dissolved oxygen, and the 

 successional stage (Parker and Revelas 1989). 



RPD values at PDS in July ranged from to 3.28 cm (Figure 3-6). Most RPD values 

 (21 stations) were between 1.5 and 3.4 cm. Seventeen stations on the disposal site had 

 indeterminate values due to condensation on the camera lens. At the reference stations where 

 data was collected (23 stations), 17 stations had RPDs between 1.5 and 3.4 cm (Figure 3-7). 



At PDS, 18 out of 42 REMOTS® stations had indeterminate successional stage values 

 due to condensation on the camera lens. Where the successional stage could be determined, 

 21 out of 24 stations had Stage in organisms (Figure 3-8). Stage I organisms were found at 

 three stations: El, F3, and F9. At the reference stations, Stage IJJ seres were found at 17 

 out of 23 stations. Stage I taxa were found at SREF stations 200E and 300E. Three stations 

 were indeterminate. 



OSI values at PDS ranged from 3 to 9.5. Since the OSI value is dependent on the 

 RPD and successional stage values, as well as other factors, 19 stations at the disposal site 

 were indeterminate (Figure 3-9). Of the remaining 23 stations, five had OSIs less than +6, 

 indicating areas that were stressed. At the reference areas, OSIs at two out of 23 stations 

 were indeterminate, three were below +6, and the remainder ranged from six to 11. The 



Monitoring Cruise at the Portland Disposal Site, July 1992 



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