minimum thickness of 50 cm to one 

 meter is required for the cap; chemical 

 isolation by the physical covering of 

 sediment can be achieved usually with 

 a layer of approximately 35 cm 

 (Gunnison, et al., 1987). The additional 

 15 to 65 cm is recommended as 

 insurance against excessive perforation 

 of the capped layer by burrowing 

 infauna. The majority of bioturbating 

 fauna in Long Island Sound are found 

 in the upper 15-20 cm of sediment 

 (Germano, 1983); however, 

 stomatopods (e.g., Squilla) . decapods 

 (e.g., Homarus), and some fish (e.g., 

 Urophysis) can burrow much deeper 

 than this, sometimes in excess of a 

 meter. However, the densities of these 

 burrowing megafauna are low enough 

 to dismiss the occasional perforation of 

 the cap by their burrow as not serious 

 enough to compromise the integrity of 

 the overall cap function. 



Sediment samples are to be taken 

 with a grab both on the disposal 

 mound and at the reference stations 

 for baseline chemical characterization; 

 unless the permit evaluation testing 

 has identified a unique organic 

 compound as a signature for the 

 underlying contaminated material, the 

 sediments will be tested for physical 

 characteristics (grain-size) and the 

 same suite of contaminants as done for 

 the initial permit evaluation. 

 Obviously, if a unique chemical 

 signature has been identified for the 

 contaminated material, levels of that 

 compound will also be analyzed (with 

 the expected results being a no 

 detection level). In the absence of any 

 unique chemical signature, these 

 "time-zero" levels are not to test any 

 null hypothesis, but to serve as a 



baseline level against which future 

 sediment tests shall be compared (e.g., 

 Box 3.14). 



Underlying Assumptions : Once 

 monitoring is initiated following this 

 protocol, it is assumed that complete 

 physical coverage of the contaminated 

 sediment has occurred and been 

 verified by the bathymetry and 

 REMOTS® surveys. The other, and 

 equally important assumption, is that 

 the cap material has low contaminant 

 levels and is verified as not having a 

 toxic bioassay response, to eliminate 

 phenomena such as the recolonization 

 anomaly witnessed at the MQR 

 disposal mound at the Central Long 

 Island Sound Disposal Site. 



Sources of Uncertainty : If the cap 

 material has low bulk chemistry 

 contaminant levels, there would be no 

 need to go through the expense of 

 bioassay/bioaccumulation testing as 

 part of the initial permit evaluation. 

 There still remains a very small 

 possibility that some "mystery 

 compound" not analyzed could be 

 responsible for causing an anomalous 

 recolonization pattern. However, 

 unless the majority of monitoring 

 results from routine unconfined open- 

 water disposal monitoring (Figure 2) 

 shows that there are serious problems 

 with the evaluation protocol, there is 

 no reason to justify the additional 

 expense of bioassay testing for capped 

 material when the normal evaluation 

 procedure shows it is not warranted. 

 If one were to "err on the conservative 

 side" as an added level of safety for 

 capped projects, one could argue by 

 the same logic that the same 

 conservative steps should be taken for 



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



