To perform a similar encasement operation by using grout the cost 
varies substantially if formwork is used. Without formwork, the cost is 
estimated at $2,400,000. With formwork, the cost of the forms and the 
time at sea to place the forms, results in a total cost estimated at 
$4,000,000. 
All of the costs are attractive when compared to a salvage operation. 
The operation to salvage the Russian submarine using the Glomar Explorer 
cost over $400 million, which includes the cost of building the vessel, 
barge, and recovery claw. The Glomar Explorer was recently refitted for 
mining operations at a cost of $50 million. The barge is being refitted 
for ocean thermal energy experiments by the Department of Energy. The 
recovery claw has, reportedly, been scrapped. If the Glomar Explorer 
and its auxiliary equipment were to be recommissioned for another subma- 
rine recovery task, the cost would be on the order of $100 million. 
Also, the response time would be quite slow. 
The Navy's Large Object Salvage Program (LOSS) is directed toward 
salvage as one of the primary operational tasks. The system uses pontoons 
having a lift capability of 100 long tons each at a depth of 850 feet. 
The depth limitation is severe when compared to Glomar Explorer's capa- 
bility to lift a 2,800-ton submarine from 17,000 ft, or to place concrete 
at 20,000 ft for encasement purposes. However, within 850 ft the LOSS 
system would probably be used to recover a large object. The final cost 
of the recovery operation might not be less than that of an encasement 
operation, but at times there is value in having the damaged object 
available for study. 
Thus, it appears from a cost and operational standpoint that concrete 
placement is a desirable capability for the Navy to have at its disposal. 
SUMMARY 
The proposed method to place concrete at deep ocean depths is 
considered to be technically and operationally feasible. The general 
approach is to mix the concrete on a surface platform and convey the 
concrete to the seafloor by a pipeline suspended from the platform. The 
task becomes more complicated in the details, but an integration of 
technologies from the concrete industry, the oilwell industry, and the 
ocean industry enables the task to be accomplished using, for the most 
part, state-of-the-art knowledge and hardware. 
The preferred surface platform is a drill ship, which is already 
outfitted for most of the operational requirements except the concreting 
equipment, but other platforms may be used. For example, a barge can be 
outfitted with the necessary equipment including a portable drill rig to 
handle the pipestring. 
Two hardware items need to be specially designed and fabricated. 
They are the concreting head at the input end of the pipeline and the 
concrete discharge device at the lower end of the pipe. Both items are 
straightforward design tasks with little development risks. 
Conveying concrete by pipeline to deep depths places the concrete 
under conditions that are beyond previous experience, so its behavior 
needs to be verified by test. Specifically, the concrete will be flowing 
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