and water. It is a soil resource with potential beneficial use. However, 

 material from maintenance dredging may contain a variety of contaminants con- 

 tributed by man's activities (SCS Engineers 1977). 



Physical Characteristics 



Maintenance material can vary widely in content but organics are usually 

 under 5% (Table 1). Most material contains a mixture of sand, silt, and clay 

 (Table 2). Potential beneficial uses of sediments from maintenance dredging 

 will thus be site dependent--depending on the use in question and the proper- 

 ties of the candidate material. For thorough discussions of the engineering 

 properties of dredged material, the reader is referred to Murdock and Zrman 

 (1975), Bartos (1977), and Brown and Thompson (1977). 



Contaminants 



The amount of contaminants, such as petroleum hydrocarbons, pesticides, 

 PCBs, and heavy metals, vary widely in material from maintenance dredging 

 (Table 1). In general, industrial harbors are highly polluted, whereas, 

 interconnecting waterways may be relatively unpolluted. 



Nutrients 



Fine-grained maintenance material usually contains the essential elements 

 needed by plant life. In contrast, material containing a high sand content 

 may be low in nutrients because of low sorbtion affinity. 



Evaluation of Dredged Material Pollution Potential 



Man's ability to evaluate the pollution potential of dredged material has 

 improved in recent years, but is still an inexact science. The availability 

 of contaminants to the biota, the actual uptake, and the impact if uptake oc- 

 curs are difficult to predict. It is particularly difficult to develop tests 

 that will predict subtle long-term impacts. 



Two predictive techi ,^es __ bulk sediment analysis and standard acute 

 toxicity bioassays -- were widely used in the past, but have now been largely 

 discredited as sole factors for determining pollution potential. Bulk sedi- 

 ment analysis measures the gross levels of various contaminants in dredged 

 material; however, the presence of contaminants may bear little relationship 

 to the subsequent chemical reaction, release, and availability to aquatic 

 organisms after disposal. Bulk sediment analysis, however, may be useful in 

 determining potential pollutants that could have long-term significance be- 

 cause of their presence in the bottom sediments. Likewise, standard bioassays 

 that measure acute toxicity and utilize mortality as the end point give little 

 insight into long-term effects of pollutants on growth, reproduction, molting, 

 mutations, and other biological functions. The standard acute toxicity bio- 

 assay is limited to predicting short-term impacts. 



An evaluation of pollution potential of dredged material has been summar- 

 ized by Brannon (1978). He recommends the use of the Elutriate Test to predict 

 the short- and long-term chemical impacts on the water column. These results 

 should then be interpreted in light of the dispersion and dilution that will 



10 



