Duval County Summary & Conclusions

• The postconstruction beach profile had been subjected to a number of tropical storms and northeasters, which resulted in the flatter postconstruction profile shape and resulted in the relatively small average seaward extension of the mhw line.
• A volumetric gain of 1,035,828 cubic yards was measured between the preconstruction survey in May 1995 and the postconstruction survey in April 1996.  A volumetric change of +974,630 cubic yards was measured landward of the 18-foot depth contour, indicating that a volumetric gain of 61,198 cubic yards had been measured seaward of the 18-foot depth contour during this period.  A volumetric loss of 151,451 cubic yards was calculated between the final pay volume (1,187,279 cubic yards) and the total volume remaining in place at the time of the April 1996 postconstruction survey (1,035,828 cubic yards).  These losses were also due primarily to the tropical storms and winter northeasters.

• The net littoral transport throughout project area is generally southward, although frequent reversals occur throughout the year.  The fill transported southward has resulted in relative stability of the shoreline along the central and southern portions of the fill.  The Atlantic Beach and Jacksonville Beach piers appear to act as permeable groins, increasing the stability of the shoreline on their updrift sides, while some slight increase in erosion (or decreased accretion) is noted during most survey periods on the downdrift sides of the structures.
• Much of the material (43%) originally placed within the construction template has been transported offshore, seaward of the 18-foot depth contour.  The berm widths and front slopes of the beach generally remain in excess of the 60-foot design berm, but some areas of limited erosion into the design berm exist.   In general, however, the design section remained in satisfactory condition as of the June 1999 survey.
• An examination of mhw shoreline change and volumetric data indicates that erosional losses are decreasing over time as the beach fill stabilizes.  The most recent survey (June 1999) indicates substantial accretion throughout most of the project.  This gain of material may be the result of summer/winter profile adjustments between the November 1998 and June 1999 surveys, coupled with lower than average erosion due to periods of calm weather and a relatively inactive 1999 hurricane season at the time of the June 1999 survey.
• Typical renourishment intervals for this project average about 5 - 7 years.  During the period since the most recent renourishment in 1995, the area has been subjected to a higher than average number of severe storms, including near-direct impacts from a number of hurricanes and tropical storms.  Based on the existing condition of the project, renourishment is tentatively scheduled for the summer/fall of 2000.

• All the MHW and volume change data came directly from the monitoring reports.  Due to the inability to obtain the pre-construction survey data, the shoreline and volume changes BSRC normally calculates are not available at the present time.