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Responses to Questions Posed by the Subcommittee on Oceanography, 



Gulf of Mexico and the Outer Continental Shelf 



Following the March 30, 1993 Hearing on 



Ocean Disposal of Contaminated Dredged Material 



Responses to questions by Rep. Gene Green 



1. I do not know of any specific studies that estimate health risk associated with contact or accidental ingestion 

 of contaminated sediments. 



2. Dredge material is classified as clean (category I) if it does not cause unacceptable toxicity or bioaccumulation 

 in biological test systems. 



Responses to questions by Rep. Curt Weldon 



1. Extensive efforts at remediation of contaminated sediments are being made in a number of port areas including 

 Holland, Belgium, Germany and in the EPA Assessment and Remediation of Contaminated Sediments (ARCS) 

 Program in the Great Lakes. The greatest success has resulted from reduction in the amount of contaminated 

 material by physical separation of particles. Hydrocyclones and other types of mechanical separators are useful 

 for separation of sand from finer-grain fractions. Flotation followed by aheap leaching process may prove useful 

 for sediments without much sand. Solvent extraction, chemical transformation, thermal desorption and wel-air 

 oxidation are all promising approaches to remediation. 



2 and 3. Most of the current bioremediation research programs target specific classes of compounds. None of 

 the methods in present use appear to be successful for bioremediation of metal contamination. The most success 

 has been with petroleum compounds in oil spills and PCBs in sediments. Biotechnology approaches are not yet 

 ready to solve the problems associated with disposal of contaminated sediments from dredging. However, this 

 is a very active area of research and break-throughs are likely. Bioremediation should not be ignored in any 

 management strategy since natural biological processes have been shown to naturally reduce levels of 

 contamination in sediments. In situ enhancement of these natural processes should be a management goal. 



Biotechnology experts at the remediation conference held May 4-6, 1992 at Rutgers University concluded 

 that successful bioremediation procedures need to focus on a specific class of compounds. However, new 

 approaches to bioremediation are continually being proposed. For example, at a subsequent Conference held 

 November 17-18, 1992, one particularly innovative approach was suggested by Professor James Watson of the 

 University of Southampton in Great Britain. He suggested that microorganisms could be used to immobilize and 

 localize metal ions from solution which are then separated with a high gradient magnetic separation technique. 

 Polar organic compounds may also be concentrated on the metal sulfides attached to these bacteria and be 

 removed in the magnetic separation. 



4. Some of the chemical and physical treatments are likely to have immediate application and should be tested 

 with sediments presently disposed of in the ocean. Category I sediments are, by definition, not harmful and the 

 most cost-effective approaches to relocation or reuse of this material can continue. 



5. Procedures used in Norway were not discussed at the two Rutgers conferences on remediation. We received 

 useful discussion of efforts underway in Holland, Belgium, Germany and the United Kingdom. Each port is 

 working on approaches to reduce contamination in sediments but these methods are specific to particular 

 sediments. Most of the present approaches are regarded as interim procedures until better methods of 

 decontamination can be developed. Most of the technologies have been or are being tried in the U.S. None are 



