South Amelia Island Summary & Conclusions

• Three years after its construction, most of the beach remains at least 200 feet wider than the pre-construction condition.  The groin field appears to have reduced sediment losses from the beach fill at the south end of the project and has prevented the northerly migration of an erosional wave.  The total beach fill volume change is -919,000 cy.  This value is equivalent to approximately 35% of the original fill volume.
• The performance of the beach fill improves from north to south.  The northernmost 80% of the fill area has performed at or above expectations.  The southernmost 20% of the fill area eroded significantly, requiring the construction of a terminal groin field.

• Since its construction in 1995, the groin field has reduced sediment losses from the beach fill at the southern terminus of the project thereby preventing the adverse end effects associated with the construction of nourishment projects adjacent to tidal inlets.
• To the north of the groin field and to a large degree between existing structures, the shoreline is stabilized or only experiencing modest recession.  A thorough quantitative update of shoreline changes north of the groin field through the year 2000 was not possible due to the termination of the Beach Fill Monitoring Program in 1997, which was limited to the first three years after initial fill placement in 1994.  South of the groin field, the shoreline continues to be highly recessive. Accordingly, the original permit project performance "triggers" related to downdrift impacts and potential mitigation have been exceeded.
• The large scale recession of the shoreline at the terminus of the island near Nassau Sound is essentially natural in occurrence, as documented by existing historical aerial photography and survey data.  It is important that this fact be acknowledged since it is reasonable to assume that public perception may be that those land losses are related solely to groin construction.  It is opined that the dynamic phenomena resulting in large scale losses is essentially unrelated to the existence of the groin field.

• The 2002 Phase I shore stabilization project has performed satisfactorily during its first year following project completion.  The beach fill is however undergoing a relatively unique equilibrium process due to a variation in the composition of the sediments excavated from within the permitted borrow area.
• The annualized sediment volume loss from within the project limits was 360,000 cy.  This compares well with the documented losses from the SAISSA (94) project over the first three years of monitoring.
• Seaward of, and immediately north of the Amelia Island State Park, the advance placement of an additional volume of coarse sediment (intended to eventually impound adjacent to the Phase II structures) has resulted in a relatively significant depositional spit.