There was no evidence of low-reflectance dredged 

 material layers in the northwest corner of the survey grid, where 

 it has been presumed that roughly 20% of the 1986-87 material was 

 disposed. Some clayey and sandy deposits observed in this region 

 may represent disposed material. However, given the wide range of 

 sediment types characteristic of the New London Disposal Site, it 

 is impossible to uneguivocally classify these heterogeneous 

 sediments as dredged material. It should be noted that no 

 apparent dredged material was observed at the three reference 

 stations. 



The dredged material deposit extending south, east and 

 west 200 to 400 m from the disposal point (Figure 3-3) was 

 markedly smaller in areal extent than that observed at this 

 location in July 1986. The discernible extent of the 1986 mound 

 can be expected to shrink over time as a result of bioturbational 

 mixing on the flanks of the deposit. Such mixing can erase 

 evidence of thin layers of deposited material by homogenizing 

 near-surface strata. This phenomenon was documented on the flanks 

 of the Field Verification Program (FVP) mound during the first 

 year of monitoring (SAIC, 1982) . In addition, significantly less 

 material was disposed at the NL-85 buoy in the past year relative 

 to prior years. It was therefore likely that the dredged material 

 deposit by REMOTS (Figure 3-3) largely consisted of material 

 deposited prior to the July 1986 survey, with a minor addition of 

 material deposited in the past year. 



As determined from REMOTS images, surface sediments at 

 most stations consisted of mixtures of silt-clay and very fine 

 sand (>4-3 phi) (Figure 3-6) . Slightly coarser-grained sediment, 

 consisting of very fine and fine sands (4-3 and 3-2 phi) , occurred 

 in the southwest and in the northwest corner of the sampling 

 grid. At several stations (2-200SW, 200W, 400W, and 4-200NE) , 

 layers of fine sand overlaid silt-clay (Figure 3-7) . This 

 possibly reflects inputs of coarse-grained dredged material. 

 Sediments at the three reference stations consisted of silt-clay 

 to very fine sands (>4-3 phi) . 



The frequency distributions of boundary roughness values 

 for the disposal area and reference stations (Figure 3-8) indicate 

 that no significant difference exists between these stations (Mann 

 Whitney U-test; p = 0.4603) . Also, there has been no change in 

 small-scale bottom roughness in the vicinity of the NL-85 mound 

 since the July 1986 survey (Mann-Whitney U-test; p = 0.2929) . 



The mapped distribution of apparent RPD depths at the 

 disposal site (Figure 3-9) reveals that most stations exhibited an 

 RPD depth greater than 3.0 cm. Five stations from the disposal 

 point south (CTR, 200S, 400S, 400SE, and 1000S) show values 3.0 

 cm. All three reference stations exhibited average RPD depths 

 3.9 cm. Overall, RPD values were significantly shallower at the 



