62. In an even more radical departure from conventional side-scan sonar 

 inspection techniques, Hydromar rotated the towfish to a vertical position by 

 mounting it on a track attached to their frame. They then used a winch and 

 cable to move the towfish up and down while the ship was stationary. Using 

 this technique, the unit could be made to view a 100- to 150-ft-long section 

 of the wall from top to bottom. Missing vertical members of the wooden fender 

 piles could be seen. 



63. The US Navy contracted with Steadfast Marine, Inc. (1982), to 

 perform an inspection of some of the Piers at their facility in Norfolk, 

 Virginia. The quality of the records was improved by rotating the fish, 

 allowing it to look down the pilings from the surface. As a result, the 

 fender pilings stand out in greater detail than the concrete support piles 

 which are some distance behind the wooden fender piles (Figure 35). Also, 

 intact wooden piles, concrete piles, and damaged wooden piles can be seen in 

 Figure 35. 



Dredged Material Disposal Sites 



64. As nearshore and offshore open-water disposal of dredged material 

 becomes increasingly popular, the need to monitor these disposal sites will 

 become more important. While these disposal sites are not strictly classified 

 as coastal structures, management of these sites is an important part of a 

 district's dredging program. Side-scan sonar has already proved to be an 

 effective monitoring tool for monitoring disposal sites (US Army Engineer 

 Division, New England (NED) 1985). The side-scan sonar systems used for moni- 

 toring disposal sites are the same as or similar to those used for coastal 

 structures. The following paragraphs describe several instances where side- 

 scan sonar has been successfully used to monitor open-water dredged material 

 disposal sites. 



65. The Disposal Area Monitoring System (DAMOS) Program has been 

 operating within NED since 1977. DAMOS is a multidisciplinary project 

 covering many aspects of dredged material disposal monitoring and management 

 (NED 1985). Among the many monitoring techniques is side-scan sonar, which 

 has been used at all or most of the nine active disposal sites. Side-scan 

 sonar is used to verify bottom conditions prior to disposal, supplement 

 bathymetric measurements of mound shape, check for large debris in disposal 



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