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QUESTION: 



a. How far are we from employing ARCS technologies on a meaningful basis? 



b. How much of the existing contaminated dredged material can be rendered 

 "clean" by ARCS technologies? At what cost? 



ANSWER: 



The technologies demonstrated at the pilot scale by the ARCS Program are 

 all well developed and are at a point where scale up is possible. Thermal 

 desorption units have already been used to remediate a PCB-contaminated 

 sediment Superfund site in Waukegan Harbor, Illinois. The sediment 

 washing process, successfully demonstrated on low level (2ppm) PCB 

 contaminated sediments in the Saginaw River and Bay, has been used on a 

 full scale basis in several European sediment remediation projects, and on 

 several upland contaminated soil projects in the U.S. Application of 

 decontamination technologies, even when technically feasible, is most 

 appropriate where the economics of the situation justify the subsequent 

 reduction in the risk posed by the sediment contaminants. We are not yet at 

 a point where an inexpensive panacea technology has been developed for 

 application to all contaminated sediments. 



The effectiveness of decontamination technologies varies depending upon 

 the particular contaminants and kind of sediment being treated. Thermal 

 desorption can remove up to 99 percent of the volatile organic compounds 

 and semivolatile organic compounds from contaminated sediment at a cost 

 of $100- $450 per cubic yard. Solvent extraction has removed up to 90% of 

 PCBs in harbor sediments at a cost of $200-$600 per cubic yard. Sediment 

 washing can remove 90-99 percent of the volatile contaminants and 40-90 

 percent of the semivolatile contaminants at a cost of approximately $50 per 

 cubic yard. Dechlorination has resulted in removal of more than 98 percent 

 of PCBs in contaminated sediment at a cost of $200-$500 per cubic yard. 

 The effectiveness of biological treatment varies depending upon 

 characteristics of the sediment. Costs of $50-$80 per cubic yard have been 

 documented for biological treatment. It is important to note that for 

 sediments contaminated with much lower levels of contaminants, as is the 

 case with most dredged material, the analysis of treatment technology 

 efficiencies, and the overall effectiveness of these technologies, is difficult 

 to assess. 



