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sea floor" (Spencer 1991 , p 2). The waste stream considered in these WHOI/MIT workshops 

 was sewage sludge, fly ash from municipal incinerators, and dredged material. The WHOl 

 workshop developed the research program requirements for the experiment, and the MIT 

 workshop reviewed potential systems for monitoring the waste deposit. 



The recommended 10-year, industrial scale expenment was not pursued, in part, due to the 

 environmentally controversial nature of such a full-scale experiment. Continuing waste disposal 

 problems, particularly those of managing/disposing of contaminated dredged materials, as 

 indicated by the conduct of a Congressional hearing (House Hearing 1992), have stimulated 

 further interest in the abyssal seafloor disposal option. 



Strategic Environmental Research and Development Program Project 



The Naval Research Laboratory (NRL) responded to the FY93 Congressional tasking with a 

 proposal to the Department of Defense Strategic Environmental Research and Development 

 Program, titled "Technical and Economic Assessment of Storage of Industrial Waste on Abyssal 

 Plains." Our proposal was funded in November 1993, sdl research and development work was 

 completed in September 1994, and the last of six reports was submitted for printing in September 

 1995. The effort was limited to a paper study addressing the same materials as the WHOI/MIT 

 workshops. During the course of our work we adopted a shortened version of the project title, 

 "Abyssal Plains Waste Isolation (APWI) Project." 



To carry out the APWI Project work, NRL augmented its in-house expertise in oceanography, 

 geology, and geophysics with industrial expertise for most of the technical assessment 

 (Oceaneering International, Inc.) and academic expertise for portions of the environmental 

 assessment (geochemistry, Richard Jahnke, University of Georgia; benthic biology, Gilbert 

 Rowe, Texas A&M; and physical oceanography, Curtis Collins, Naval Postgraduate School) and 

 for the economics of waste handling (Di Jin and Hauke Kite-Powell, WHOI). 



Technology Assessment - The technology assessment for transporting and placing wastes on the 

 abyssal seafloor was approached by first conducting a patent search to identify all potential 

 applicable concepts and then assessing the technical feasibility of each. Four concepts emerged 

 from the 128 patents as being most technically feasible for lowering waste through 6,100 m to 

 the abyssal seafloor. They are synopsized as: 



1) Controlled lowering of the waste in a tethered bucket with a 250 metric ton payload; 



2) Pumping the waste down twin 1 .37-m (54-in.) diameter, 7600-m long pipes; 



3) Containing a barge-load of wastes in 50 geotextile bags (380 m' per bag) and free- 

 falling the waste-filled bags to the seafloor; and 



4) Carrying 153 waste-filled bags (127 m^ per bag) to near the seafloor in an unmaimed 

 submersible and free-falling the bags from 200 m above the seafloor. 



Sewage sludge would not be readily moved to and maintained in a fixed position on the abyssal 

 seafloor because of its relatively low bulk density (1.04 MN/m' (65 Ib/ft^)) which is slightly 



