material, verify the extent of the disposal mound, and check mound erosion by 

 the presence of erosive bed features. 



66. Two more examples of using side-scan sonar to monitor disposal 

 sites follow. Side-scan sonar was extensively used to monitor the Dam Neck 

 Disposal Site off the Virginia Coast (Hands and Deloach 1984). Figure 36 

 shows maps produced from side-scan sonar records that illustrate the initial 

 mound boundaries and how they changed through time (Clausner 1987). Changes 

 in the Dam Neck Disposal Site are shown in the predisposal map (36a) and the 

 postdisposal map (36b) produced from side-scan sonar records. The large, low 

 backscatter area in the center of the postdisposal map represents the foot- 

 print of the disposal mound. Smaller, low backscatter areas scattered farther 

 afield represent deposits of the finer-grained disposal material. During the 

 Duwamish Waterway Capping Demonstration Project, side-scan sonar was used to 

 provide an estimate of the extent of the sand cap placed over contaminated, 

 fine-grained dredged material (Truitt 1986). 



Other Applications 



67. Side-scan sonar has been used for a variety of other coastal engi- 

 neering related applications. One of the first was to inspect construction of 

 artificial islands for oil exploration in the Arctic (Patterson, Shak, and 

 Czerniak 1982). Concrete mats used for bank protection along the Mississippi 

 River have been inspected with side-scan sonar. The oil industry regularly 

 uses it to inspect conditions and verify location of pipelines. Side-scan 

 sonar has also been proposed as an inspection tool for the Ocean Thermal 

 Energy Conversion plant cold-water intake pipes (Mazel 1984). 



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