43 



initially. If a cap of a different grain- 

 size is a known initial condition, 

 rejection of the null hypothesis would 

 lead to Box 3.6, but no further action 

 would be warranted, because the 

 answer to the question posed in Box 

 3.7 is a given. 



Box 3.6 



"Evaluate Physical Effects ' 



Samples for sediment grain-size 

 would be taken only if an anomalous 

 grain-size major mode is not obvious 

 from the REMOTS® photographs (and 

 would need ground truth 

 confirmation) or it was not already a 

 given that capping operations had 

 been carried out with fine or medium 

 sand. The chances for the need of 

 having to take samples at this point if 

 one arrives at this box via Box 3.5 are 

 exceedingly slim; the cap sediment 

 grain-size would be known from both 

 the REMOTS® surveys done up to this 

 point and the initial sediment 

 characterization done in Box 3.1. 



Box 3.7 "Have The Physical Properties 



of the Mound Changed? " 



If one arrives at this box via Box 

 3.5, the initial recruitment pattern may 

 be different if a sand cap is used to 

 cover the contaminated material. If 

 one arrives via Box 3.11, the effects of 

 erosion and scour could be affecting 

 the normal recolonization pattern; 

 these are discussed in more detail in 

 the previous section in the text 

 following Box 2.6. The unstated null 

 hypothesis being tested is: 



H„: The sediment grain-size major 

 mode on the disposal mound is 



not different from the ambient 

 seafloor. 



Acceptance of the null hypothesis 

 would lead to Box 3.8 to explore 

 possible sediment toxicity due to 

 chemical impacts; rejection of the null 

 hypothesis would lead to Box 3.10. See 

 the discussion under Box 2.6 in the 

 previous section for underlying 

 assumptions and sources of 

 uncertainty. 



Box 3.8 "Collect Sediment For 



Laboratory Bioassay Studies 

 On Selected Infaunal Species " 



If there is no apparent physical 

 effect responsible for the anomalous 

 recolonization pattern detected, then 

 sediment samples must be collected 

 from both the disposal mound and the 

 reference stations to examine the 

 possibility of sediment toxicity. 

 Sediment samples are needed from the 

 reference areas both to serve as a 

 control for the laboratory bioassay and 

 to eliminate the possibility of general 

 regional deposition of material which 

 may be affecting recolonization 

 adversely (e.g., unusual storm runoff 

 or heavy CSO output which could 

 dump a high contaminant load in an 

 area such as western Long Island 

 Sound). If the latter possibility were 

 true, one would expect to see a toxic 

 response in the laboratory both to the 

 experimental (mound) sediments and 

 the controls (reference stations). Once 

 again, both the original protocols used 

 in the permit, testing (EPA/NED, 1989) 

 or additional tests may be added to 

 evaluate the possible causes for 

 anomalous recolonization; see the 

 previous discussion under Box 2.7 for 



An Integrated, Tiered Approach to Monitoring and Management of Dredged Material Disposal Sites 



