Fig. 9. Shoreline undulation impact on typical beach fill design.

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justification (project benefits) for the overall project. In the case of Fire Island, major

project benefits result from the reduction of storm damages within the estuarine-margin

communities along the northern shoreline of Great South Bay. In fact, these "off-site"

benefits outweigh the benefits derived from the protection of properties on Fire Island.

The project will provide storm damage protection to the upland properties by preventing

breaching of the barrier island, which would lead to higher water levels in Great South

Bay and associated flooding of the low-lying communities that border the bay. Therefore,

a major design goal is to prevent breaching of Fire Island. Another design goal is to

reduce storm-induced damages to structures and properties on Fire Island. Both of these

design goals can be achieved through the construction of a dune and a wide protective

berm. However, as illustrated in Fig. 9, the occurrence of shoreline undulations will tend

to locally degrade the effectiveness of the typical design.

One approach to designing for the presence of shoreline undulation would be to

construct an even wider beach berm (a "shoreline undulation buffer" zone) upon which

shoreline undulations could form without compromising the design berm width or

significantly impacting the advanced nourishment berm. This approach however, would

Gravens