Outfitting the barges or mining ships or re-outfitting the Explorer for 
multi-million pound anchor deployment would be very expensive, as dis- 
cussed in the cost estimate section below. 
A method has been proposed for free-fall emplacement of large 
deadweight anchors in deep water where seafloor site conditions are 
favorable. This method is designed for applications in which precise 
positioning is not critical, such as a single point deep ocean mooring 
but is not appropriate for those cases where more precise positioning is 
important, for example, placing an object at a predetermined seafloor 
position or placing objects in close proximity to each other. Free- 
falling is not an appropriate emplacement technique for all sites at 
which very large deadweight anchors would be used but only for those 
sites with a soft seafloor at a fairly flat slope (Ref 2). 
An alternative to lowering or free-falling a massive anchor is to 
combine pre-fabrication and in situ methods as commonly practiced for 
steel and concrete construction. A shell would be free-fallen or lowered 
to the seafloor using existing lift capability and then filled with a 
heavy material emplaced from the surface platform (Figure 1). Concrete 
is a prime candidate for the heavy material. Concrete normally weighs 
about 150 lb/cu ft; suitable mixes can readily be produced in weights up 
to about 200 lb/cu ft by using iron ore aggregates. This compares with 
high density oilwell slurries which weigh up to about 135 lb/cu ft when 
weighted with barite and to 160 lb/cu ft with magnetite. The shell, 
made of concrete or other materials, would be 100 feet or more in diameter. 
The mooring connection and other hardware would be built into the shell 
as needed. 
Hardening 
If an object of strategic significance is lost on the seafloor, a 
decision to salvage the object could be expensive, particularly if the 
object is lost in deep water and is very large, such as a ship or subma- 
rine that is too heavy to lift in toto. A recovery operation comparable 
to the Glomar Explorer's retrieval of a portion of a 2,800-ton submarine 
from 17,000 ft would cost perhaps on the order of $100 million. This is 
below the reported $400 million cost of the original Glomar Explorer 
expedition because the vessel and the technology now exist. 
Concrete placement makes another option available for consideration. 
Rather than salvaging the object it is encapsulated in place on the 
seafloor by covering it with concrete (Figure 2). The purpose is to 
sequester the object in such a way as to deny observation, access or 
removal of portions of it by others. The operational cost for encasing 
a ship-sized object is estimated to be about $2 million. A cost break- 
down is shown in a following section. This is a substantial savings 
compared to a recovery operation. 
For smaller-sized objects such as an airplane or weapon system, in 
situ hardening may also have application in those cases where concrete 
encasement is faster and costs less than recovery. The retrieval of the 
