50 



sediment bulk chemical analyses and 

 lead to the same types of problems 

 with interpretation as discussed under 

 Box 1.4 in Section 2. 



Box 3.19 "Evaluate Areal Extent of 



Toxic Material" 



If there is no evidence of 

 contaminant migration, then an errant 

 disposal event is the only logical 

 explanation for the observed pattern 

 occurring to this point. A REMOTS® 

 survey should be repeated over the 

 established mound sampling grid to 

 see if any surface layer of new 

 material (distinguishable by a visual or 

 textural discontinuity in the upper 

 sediment layer) has been deposited on 

 the mound. 



Box 3.20 "Does Errant Material Cover 



Substantial Portion of 

 Mound?" 



If errant material is not detectable 

 in any of the REMOTS® photographs, 

 then one must assume the errant 

 disposal event(s) happened sufficiently 

 long ago or resulted in a relatively thin 

 layer so that it could be re-worked 

 through bioturbation and visually 

 indistinguishable from the original cap 

 sediment surface. The other 

 possibility is that the sediment used 

 for the cap had high contaminant 

 levels (i.e., was unsuitable as capping 

 material). If errant material is visible 

 on the surface of the mound but only 

 at one or a few stations, one must 

 decide whether the additional expense 

 of capping the entire mound is 

 justified (Box 3.22), or if one should 

 wait and watch for the effects to 

 disappear through dilution with the 



background sediments through natural 

 depositional processes and subsequent 

 bioturbation (Box 3.10). However, 

 because one has reached this box 

 because of a toxic response from 

 laboratory bioassays (Box 3.9), the most 

 conservative management action 

 available is to proceed to Box 3.22 and 

 cover those areas of the cap with more 

 suitable capping material as soon as 

 possible. 



If only a small amount of errant 

 material is detected and has been 

 determined as the source of the 

 problem, it would be the final decision 

 of the DAMOS program manager at 

 NED on whether or not additional 

 capping operations should be carried 

 out at this particular location. If the 

 decision is made to wait, one would 

 return to Tier 1 and Box 3.10 to 

 reassess the situation in 6-12 months 

 (Box 3.20 can be reached with no 

 bioaccumulation testing if this 

 pathway is taken during the first year 

 of monitoring via Box 3.5). 



Box 3.21 "Evidence of Contaminants 



Migrating Through Cap?" 



See the discussion above for Box 

 3.18. The one major difference 

 between this box and Box 3.18 is that 

 one has arrived here because tissue 

 contaminant levels and/or surface 

 sediment levels are higher than time 

 zero. Instead of analyzing for the 

 entire standard suite of contaminants 

 in each vertical section, one need only 

 analyze for the contaminant(s) shown 

 to be elevated in the tissues or surface 

 sediments. 



If a gradient can be demonstrated 



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



