(i.e., dredge). Cialone and Stauble (1998) document historical ebb shoal mining 

 operations and note several issues that should be considered: 



(1) Mining an ebb shoal can be a major or minor perturbation to an inlet system, 

 depending on the volume mined, depth of mining, and location on the shoal. The 

 impact of ebb shoal mining will to some extent be experienced by all other parts of 

 the system. 



(2) Use of an ebb shoal as a source of sand will likely cause an increased rate of 

 downdrift erosion because any material that was formerly naturally bypassed will 

 now go to fill in the ebb shoal. Walther and Douglas (1993) concluded that impacts 

 would be reduced with shallow cuts. 



c. The flood shoal is also a source of material that may be used for bypassing. McCormick 

 (1971) determined that the Shinnecock flood shoal contained sand very similar to that 

 found along the open coast. However, little is known about the consequences of flood 

 shoal mining on inlet and bay circulation. Therefore, it is probably safe to assume the 

 same recommendations from HQUSACE (1991) for ebb shoals-if the volume of material 

 to be removed is a small percentage of the flood shoal volume, no adverse consequences 

 would be expected. Similar to ebb shoal mining, a floating plant will likely be required, 

 even if it has significant exposed dry beach, because of its isolation from stable land. 

 Concerns related to mining the flood shoal include effects to the tidal prism and possible 

 wetland habitat impacts. 



d. The navigation channel may be considered as a source of material for bypassing, 

 especially if periodic maintenance dredging is required. In many instances, a typical 

 maintenance dredging plan calls for removal of channel material, which is then placed at a 

 downdrift beach. This is essentially "sand bypassing" by another name. If shoaling 

 quantities are sufficient in both volume and time, a sand bypass system may be merely a 

 specific plan to place channel maintenance material at the appropriate place on downdrift 

 beaches. 



If required bypass quantities are too large for any one of the sources listed above, then a 

 combination of sources may be used. For example, a specified quantity may be removed from 

 the subaqueous updrift fillet, navigation channel, and ebb shoal by floating plant that together 

 would minimize specific source impacts, yet still achieve the desired total quantity. For 

 example, at Indian River Inlet, the fixed bypassing has been supplemented by flood shoal mining 

 (Clausner et al. 1991). 



Placement options 



The area west of Shinnecock has two problem erosion areas that would benefit from beach 

 nourishment activity. As mentioned previously, the erosion hotspot directly adjacent to the west 



46 Chapter 4 Design Criteria 



