and distance from shore. Only two stations along the transect 

 (T-8 and T-3) show distinct evidence of bottom disturbance 

 (Figure 3-22). All remaining images show an "undisturbed" bottom 

 with an intact RPD layer and dense Stage I assemblages (Figure 

 3-23) . Given that widespread disturbance was evident on the 

 deeper WLIS disposal mounds, the general lack of disturbance 

 along the WLIS transect (ranging in depth from 10 to 30 meters) 

 is notable. The sediment stabilizing effects of the dense mats 

 of Stage I organisms most likely influenced the pattern of bottom 

 disturbance. Stage I assemblages within the WLIS survey area 

 were comprised of many fewer animals per cm^ . 



4.0 SEDIMENT CHARACTERISTICS 



26. During the August 1985 survey at the WLIS disposal 

 site, replicate sediment grabs were collected with a Smith- 

 Mclntyre grab sampler (0.1 m^) at the center of mounds "A", "B", 

 "C" and the reference site (see Figure 2-1) for physical and 

 chemical analysis by NED. The sediment at all four sites was 

 described as dark grey organic sandy silty clay, with shell hash 

 also present at the reference site. The pH varied from 6.9 to 

 7.2 and the specific gravity from 2.62 to 2.68. Samples at the 

 center of mound "C" contained as much as 87% silt/clay, while 

 sediment from mounds "A" and "B" contained 58% and 60%, 

 respectively. The reference site sediment contained 78% 

 silt/clay. 



27. Table 4-1 presents the results of the chemical analysis 

 of the sediment at the four sites. No major trends are evident 

 in the data, although the sediment at the reference site tends to 

 have reduced concentrations of Pb, Or, and Cu. Mound "C", the 

 site of recent disposal operations, contains sediment with higher 

 concentrations of Fe and Cu and lower concentrations of Zn. 



28. Comparisons of these results with data collected in 

 June 1984 at mounds "A" and "B" and the reference station 

 revealed that the concentrations of most metals are similar to or 

 less than the 1984 results. Hg concentrations are higher for the 

 August 1986 sediments, but are similar to those found at the 

 reference site. The data does not indicate any major change in 

 the level of contamination of the dredged material. 



29. Sediment samples were also collected in October to 

 assess whether there were differences in the surface sediments 

 covering the mound as a result of sediment redistribution. The 

 six stations sampled included those sampled in August 1986 and 

 were located at the center and 50 meters south of mounds "A", "B" 

 and "C". Table 4-1 includes the results from the chemical 

 analysis of these samples. 



30. The sediment at mound "A" was described as dark gray 

 clayey sand with traces of shell fragments and approximately 40% 

 fines. The sediment at mounds "B" and "C" was described as dark 



8 



