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QUESTION: 



a. How big is the problem of the disposal of contaminated sediments? 



b. Is the volume of contaminated sediment increasing? 

 ANSWER: 



a. Waterways adjacent to urban, industrialized areas are most likely to contain 

 contaminated sediment. Dredging in such areas is often a necessity to 

 maintain and improve access for naval, commercial and recreational vessels. 

 Contamination of these sediments most likely occurred before current 

 pollution control measures were implemented, though, continued 

 contamination of these sediments may be occurring from nonpoint sources 

 (e.g., urban and agricultural runoff). For dredgers of such sediments, 

 disposal can be a big problem. Even approximate estimates of the volume of 

 such sediments is difficult to make. While from a national perspective a 

 large amount of dredging is done in areas far removed from sources of 

 contamination and disposal is not a problem, disposal of the relatively 

 smaller volume of contaminated sediment presents a considerable challenge. 



Several problems can be associated with the disposal of contaminated 

 sediment. Dredging contaminated sediment can result in resuspension of 

 contaminated material, which may then become more available to aquatic 

 organisms. Disposal of the contaminated dredged material requires locating 

 a secure site, either on or off shore, where large amounts of aqueous 

 material can be safely transported and contained. Specialized dredging 

 techniques and disposal sites are sometimes required to handle the 

 contaminated sediment. Confined disposal facilities are expensive to 

 construct and are often not a feasible alternative. In addition, the 

 contaminated material must often be dewatered or otherwise treated before 

 disposal can occur. Sediment decontamination technologies have been 

 demonstrated on a pilot scale, but are costly for use on a large scale. 

 Capping contaminated dredged material with clean sediment in the aquatic 

 environment is not effective at all depths and in all environments. 



b. No data are available to monitor, on a national scale, changes or trends in 

 the volume of contaminated sediment present in U.S. waters. EPA and 

 State pollution abatement and control programs have reduced the volume of 

 toxic chemicals entering our nation's surface waters. However, toxics 

 continue to be discharged and accumulated in aquatic sediments. At many 

 sites, particularly those subject to nonpoint source contamination and 

 contaminated air deposition, the volume of contaminated sediment present 

 could be increasing. 



