Ch. 6— Environmental Considerations • 229 



Box 6-B. — U.S. Army Corps of Engineers 



The U.S. Army Corps of Engineers (COE) maintains over 25,000 miles of navigable waterways that 

 service over 155 commercial ports and more than 400 small boat harbors. About 465 million cubic yards of 

 sediment are dredged each year in the United States; most of this dredging is the result of COE projects that 

 have been approved by Congress. About 30 percent of the materieJ is disposed of in marine environments. 

 The major program addressing environmental effects of dredging and disposal conducted by the U.S. Army 

 Corps of Engineers is the Dredged Material Research Program (DMRP). This work was initiated following 

 congressional authorization for a comprehensive nationwide research program.' 



The 5-year DMRP Program was completed in 1978 at a cost of approximately $33 million; about 300 

 reports were produced as a result of this research effort. The project was designed to be applicable nationally 

 with all regions and environmentcd settings represented. The overall conclusion of the study was that physical 

 effects (such as smothering benthic communities) caused by dumping dredged material were more important 

 than chemical or biological effects. However, these effects were deemed avoidable under guidance for the Sec- 

 tion 404^ and Section 103^ programs. In general, deep ocean areas were recommended as "more environ- 

 mentally acceptable" for disposal than highly productive continental shelf areas. Except in unusally sensitive 

 environments (such as coral reefs) or at critical stages in the life cycle of animals (spawning, larval develop- 

 ment, and migration), turbidity plumes are "primarily a matter of aesthetic impact rather than biological 

 impact. " Benthic communities appear to recover if the grain-size of the sediment remains similar to the origi- 

 nal condition after dredging or disposal occurs. Recolonization both of dredged areas and disposal mounds 

 appears rapid for fine-grained sediments (silt) but requires up to 3 years for coarse-grained sediments (sand). 



Short-term impacts from dredging and dredge disposal are brief and not of major environmented signifi- 

 cance. Long-term monitoring studies still need to be done. In particular, chronic or sub-lethal effects of very 

 long-term mining operations are not known. 



'Public Law 91-611. 



^Public Law 92-500, The Federal Water PoUution Control Act, 1972. 



'Public Law 95-532, The Marine Protection, Research, and Sanctuaries Act of 1972. 



(see box 6-D) that examined naturally occurring 

 populations of organisms on the seafloor in the 

 northeastern United States where shallov^f water 

 mining operations are likely to take place. Guide- 

 lines have been established by EPA and the Corps 

 of Engineers (see box 6-E) for testing the impacts 

 of dumping dredged material which may, in turn, 

 provide information about effects of concern from 

 rejected mining material. 



The U.S. Army Corps of Engineers reports sug- 

 gest that concerns about water quality degradation 

 from the resuspension of dredged material are, for 

 the most part, unfounded. Generally, only mini- 

 mal chemical and biological impacts from dredg- 

 ing and disposal have been observed over the short- 

 term^^. Most organisms studied were relatively in- 

 sensitive to the effects of sediment suspensions or 

 turbidity. Release of heavy metals and their up- 



"R.A. Geyer (ed), Marine Environmental Pollution, Dumping 

 and Mining, Elsevier Oceanography Series 27B (Amsterdam-Oxford, 

 New York: Elsevier Science Publishing Co., 1981). 



take into organism tissues have been rare. The con- 

 clusion of the Dredged Material Research Program 

 (DMRP) is that biological conditions of most shal- 

 low water areas — areas of high wave action — 

 appear to be inlluenced to a much greater extent 

 by natural variation in the physical and chemical 

 environment than they are by dredging or drilling. 

 The NOMES and Sea Grant studies corroborate 

 the Corps of Engineer's finding, that in shallow 

 water, there is much natural variation in both the 

 distribution and abundance of species on the un- 

 altered seafloor; these latter studies conclude that 

 if is impossible to generalize about the effects of 

 mining on all shallow water environments given the 

 tremendous variability from site to site. This con- 

 clusion suggests that, if a mined area is compared 

 with an unmined area, changes due to the dredg- 

 ing might not be statistically detectable because 

 either: 



• the mining really had a minimal impact, or 



• the tremendous variability between sites masked 

 the changes that occurred at the mining site. 



