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release zone by means of a bottom pinger. 
Usefulness of CMC 
Many of the major harbors of the world require dredging of material that in 
some cases is contaminated with industrial wastes or products, including 
heavy metals, pesticides, and PCBs (Morton, 1980b). The continental shelf 
is deemed the best disposal area for this technique because of 
(a) the generally large amounts to be dredged 
(b) the usual lack of suitable upland or shoreline disposal 
sites near these harbors, and 
(c) the higher cost of transport of polluted plus clean material 
beyond the continental shelf, particularly in those areas 
where the shelf is very wide. 
Requirements for Successful CMC Operations 
The requirements for a successful capping operation, as suggested by Morton 
(1980b) appear to be « 
(a) Dredging of the "hot material" is best done by clamshell in 
order to retain cohesiveness of material. 
(b) Dumping must be precision, involving either taut-wire buoys 
or bottom pingers to mark release points. 
(c) The final surface of the mound should be as smooth as possi- 
ble to reduce erosion from waves or currents. 
(d) Smoothness is best achieved if the capping material is sand 
rather than silt. : 
11-267 O—82——30 
