60 



- ii - 



contaminates must be dealt with by further treatment. Propane 

 extraction has been used on a pilot scale in new Bedford Harbor 

 on PCB-contaminated sediments. Cost estimates range from $155 to 

 $266 a cubic meter. 



7. Other Chemical Processes - If the actual chemical makeup 

 of the contaminates in the sediment are know, there are various 

 processes to render the contaminates less harmful or inert, after 

 the sediment is dredged, and in some cases, dewatered. These 

 include the modar supercritical process, which uses a combination 

 of supercritical water, oxygen and pressure to degrade organics 

 into harmless substances; the KPEG Terraclean CI process, which 

 uses potassium hydroxide and polyethylene glycol to initiate a 

 complex chemical reaction that removes chlorine from PCB 

 molecules, producing less toxic biphenyls which do not 

 bioaccumulate; Light Activated Reduction of Chemicals, where 

 chemicals are injected into sediments, the liquid decanted and 

 placed into a reactor where it is treated with ultraviolet light; 

 and various solvent extraction processes, which involve the 

 treatment of sediments with organic solvents to remove PCBs and 

 other organics (but not metals) . 



It must be noted that most of these methods generally require 

 a single contaminant at high concentrations in the sediment to be 

 successful . 



Other Options 



1. No Action Alternative - Allowing the sediments to remain, 

 or to reduce dredging depth or location so as not to disturb 

 contaminated sediments are also alternatives to managing 

 contaminated dredge material. However, this is rarely acceptable 

 since it would preclude the channel and berth improvements and 

 maintenance that enable ports to accommodate virtually all the 

 vessels that conduct interstate and foreign commerce. 



2. Pollution Prevention - A favorite of environmental groups 

 is preventing the creation of contaminated sediments in the first 

 place. EPA is pursuing a pollution prevention strategy which is 

 not specially targeted to sediments, but that medium can benefit 

 from contact with cleaner water and fewer chances of pollution 

 from air sources. EPA sediment criteria, when completed, can 

 also help prevent pollution from reaching sediments in the first 

 place. 



