jetty is a localized phenomenon. This phenomenon is probably caused by the cutoff of waves 

 and east-directed sand transport due to the attachment of the ebb shoal to the beach as well as the 

 cutoff of westerly transport by the main body of the ebb shoal and the navigation channel. 

 Though beach nourishment is needed at this location, bypassing material updrift of this site is not 

 the ideal solution. Because the local transport between the ebb shoal and the west jetty is 

 predominantly east-directed and there is no physical constraint to hold material next to the jetty, 

 material bypassed would likely continue the current trend of traveling either through or around 

 the jetty to the inlet channel or offshore. This approach would, therefore, fail to restore the 

 regional westward transport, continue to starve the downdrift beaches, and possibly may remove 

 the bypassed material from the littoral system. Other solutions, as proposed by Moffatt & Nichol 

 (1996) (e.g., groins in conjunction with beachfill, T-head groins, etc.), are more suitable for this 

 erosion hotspot. 



The other placement options are either immediately west of the ebb shoal or directly at the 

 eroding downdrift beaches at Tiana Beach (see page 12, "Supplemental Documentation," in 

 USAE District, New York (1988) and Moffatt & Nichol (1996) shoreline change rates). Placing 

 the material just west of the shoal would be more cost-effective because of the shorter haul or 

 pump distance (2.4 km versus 4.8 km to Tiana Beach). Natural processes would then transport 

 material westward as part of the natural littoral transport. Placement at Tiana Beach would 

 immediately address the need of local residents for sand, though it may not solve their problem if 

 more material is needed than is mechanically bypassed. The Tiana Beach location would be 

 more expensive due to the longer haul or pump distance and may even preclude the use of a fixed 

 plant because of the need for booster pumps. 



There are two primary methods of placement for a bypass system: nearshore and onshore 

 (beach nourishment). These options depend on the method of bypassing used, so they will be 

 discussed in general here and elaborated on in the Alternative Analysis section. Of the two 

 methods, placing material directly on the beach is preferred because it accomplishes the desired 

 result (widening and/or raising the dry beach). Nearshore placement is a viable alternative; 

 however, design and construction of these features in shallow water is complex, and though the 

 littoral system would be nourished, onshore movement of material has not been evaluated. Also, 

 public acceptance of nearshore placement is usually marginal at best. Construction costs may 

 also become a factor in selecting one method over another. If bypassing is being conducted by 

 floating plant, nearshore placement may be preferred because of the relative ease of placement 

 from hopper dredges. Onshore placement with a hopper dredge is common through an offshore 

 buoy connection to a submerged pipe, but increased costs may be expected due to the time 

 required to pump out material. A fixed bypass plant at the updrift fillet would probably place 

 material directly on the beach through a pipeline. However, problems with the pipeline crossing 

 under the inlet and running along (or buried under) the beach can be expected. Onshore 

 placement may also require earth-moving equipment to redistribute material as it is discharged 

 from the pipe, similar to traditional beach nourishment projects (though at a reduced level due to 

 the smaller volumes). 



Chapter 4 Design Criteria 47 



