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Title: Final Supplemental Environmental Assessment: Dunes and Other Resiliency Design Refinements, Shore Protection Projects: Nassau, Duval, St. Johns, and Brevard Counties, Florida
Authors: United States. Army. Corps of Engineers. Jacksonville District.
Keywords: Shore protection
Beach nourishment
Sand dunes
Publisher: United States. Army. Corps of Engineers. Jacksonville District.
Abstract: The U.S. Army Corps of Engineers, Jacksonville District (Corps), is considering design changes to increase the robustness, resiliency, and/or reliability of existing Federal Shore Protection Projects (SPP) in Nassau, Duval, St. Johns, and Brevard counties, Florida. Detailed descriptions of these projects can be found within the National Environmental Policy Act (NEPA) reports listed in Table 1 and are incorporated herein by reference. The Corps, in partnership with local sponsors, has been implementing beach nourishment projects in Florida since 1969. The designs for most of these projects were developed in the 1960s through the 1980s. These projects were designed to control beach erosion and prevent the landward retreat of the shoreline that would cause property and infrastructure damage. The general understanding at the time was that the best way to address the problem of landward erosion was to build a wider beach berm. Dunes were often investigated as an alternative in the plan formulation process for these projects, but typically were eliminated from further consideration. Dunes were thought only to protect against storm surge flooding and vertical erosion which were not considered to be significant problems along the coast in the project areas. Beach recreation was also an important consideration in the development of these projects. The general understanding at the time was that wider beach berms would increase recreational opportunities while dunes would take up beach space that could otherwise provide recreational value. This SEA considers a range of alternative design modifications that could increase project resiliency, including dune construction with vegetation, vegetation only, sand fencing, pedestrian access modifications, vehicle access modifications, and outfall pipe modifications. To assist in this analysis, the Corps evaluated the performance of existing dunes, including reducing erosion and inundation damages, elongating nourishment intervals, decreasing nourishment volumes, and incidental environmental benefits. A generalized dune template was developed for comparison to the existing beach template; the dune template could include elongation of existing dunes, closure of existing gaps in the dune line, realignment of the current dune line, or creation of dunes in areas where they do not currently exist. As noted above, the Corps also analyzed vegetation-only and sand fencing design alternatives, which can further enhance dune stability and beach accretion rates.
Description: Environmental Assessment / Finding of No Significant Impact
Rights: Approved for Public Release; Distribution is Unlimited
Size: 188 pages / 8.722 Mb
Types of Materials: PDF/A
Appears in Collections:Environmental Documents

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