jetties at Oregon Inlet. DOI administers the Federal lands adjacent to Oregon 

 Inlet on which the proposed jetties must be anchored. 



88. The DOI plan attempted to minimize disturbance of park and refuge 

 lands by proposing that material dredged from the inlet be placed in the near- 

 shore zone as close to the beach as possible by small split-hull hopper 

 dredges. This was in lieu of hydraulically transporting the dredged material 

 from the inlet along the beach via a pipeline with disposal being accomplished 

 in a manner similar to that in conventional beach nourishment. The DOI pro- 

 posal assumed the dredged material placed in the nearshore zone would be dis- 

 persed shoreward by wave action at a rate sufficient to prevent dredging- 

 induced beach erosion. 



89. The only dredging plants that have the capability to quickly dispose 

 dredged material in the shallow nearshore zone in the presence of waves are 

 the CURRITUCK and ATCHAFALAYA/MERMENTAU class split-hull dredges. The split- 

 hull design allows these dredges to dump their loads very rapidly and at the 

 same time rise quickly to a shallow draft, thus avoiding the danger of 

 striking the bottom. The CURRITUCK class dredge has a hopper capacity of 



315 cu yd, an unloaded draft of 3 ft, and a loaded draft of 8 ft. The 

 ATCHAFALAYA/MERMENTAU class has a hopper capacity of 1,300 cu yd, an unloaded 

 draft of 5.7 ft, and a loaded draft of 14 ft. 



90. The US Army Engineer District, Wilmington (SAW) (1983), performed a 

 feasibility study for the plan proposed by the DOI. Material dredged from the 

 inlet would be placed in a nearshore disposal area as shown in Figure 34. The 

 disposal zone would begin at a point approximately 12,500 ft from the seaward 

 end of the entrance channel. At this location, the ebb-tidal delta ceases to 

 exist; and bottom contours are essentially parallel to the shore. Placement 

 of material closer to the inlet than this point would cause the material to be 

 in the ebb-tidal delta area. Material in the ebb-tidal delta typically would 

 not be transported to adjacent beaches; thus erosion of the beaches would be 

 accelerated. Much of the material also would move toward the inlet and 

 quickly reenter the navigation channel. The farthest disposal point would be 

 located approximately 65,000 ft from the seaward end of the ocean entrance 

 channel . 



91. The split-hull dredges would place material in the nearshore zone by 

 dropping it in the pattern shown in Figure 34. Dimensions of the disposal 

 mounds were determined by SAW based on the length and breadth of the vessel 



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