Table 5. Areas aiid estimated quantities required for beach erosior 



1 control.' 



Area 



Shoreline length 



Initial fUl 



Nourisliment 



Initial fill 







Annual 



50-Year 



+ 50-year nourishment 







XIO^ 



XlO^ 



XIO^ 



XIO^ 



Duval County^ 



about 10 miles 



3.75 



0.26 



13.0 



16.75 



St. Johns County^ 



about 5 miles 



3.05 



0.56 



28.0 



31.05 



South Ponte Vedra Beach 



11,600 feet 











Anastasia Beach 



7,600 feet 











Cresent City Beach 



7,500 feet 











Total 





6.8 



0.82 



41.0 



47.8 



1. Cubic yards. 



2. Beach Erosion Control Study, Duval County, Florida (U.S. Congress, 1965). 



3. Beach Erosion Control Study, St. Johns County, Florida (U.S. Congress, 1966). 



3.75 X 10^ cubic yards of sand for initial fill and about 0.26 X 10^ cubic yards annual 

 nourishment (Table 3). Including initial fill, nearly 16.75 X 10^ cubic yards of material 

 will be needed to restore and maintain this area in Duval County for a 50-year period. 



Erosion in St. Johns County occurs principally at South Ponte Vedra Beach, 

 St. Augustine Beach, and Crescent City Beach, and approximately 3.5 X 10^ cubic yards 

 of sand will be required for initial fiU and over 0.5 X 10^ cubic yards for yearly 

 maintenance (U.S. Congress, 1966). Over 31.05 X 10^ cubic yards will be required for 

 restoration and nourishment of these beaches over a 50-year period. 

 2. Comparison of Beach and Offshore Sands. 



Beach-fUl sand, to be well suited for restoration and maintenance should closely match 

 the size distribution of native beach material, be mechanically and chemically stable, and be 

 reasonably free of fines and foreign material (such as sharp coral fragments) which might 

 degrade the quality of the beach for recreational purposes. 



Type A deposits occur in a wide range of characteristic sizes, thus reasonably good 

 matches for typical sand on north Florida's Atlantic beaches can be defined. However, 

 deposits suitable for some areas may not occur within economic transport distance of the 

 project site or in the volume required for borrow operations. 



Beach samples from along the active profile of the northeast Florida coast range from 

 very fine to very coarse sand; the vast majority of samples are fine sand size, but range from 

 about 0.1 to 0.4 millimeters. Median sieve diameters averaged by profile position for each of 

 three Florida counties are presented in Table 6. Ranges of median diameters are also 

 presented to provide information on between-profile variability. Most anomalously coarse 

 sizes shown on median size range reflect the local occurrence of shell material. Size range of 

 beach samples, taken from several literature sources, is compared to size ranges of offshore 

 type A sands in Figure 39. In general, comparison of ranges of median and mean grain-size 

 values shows that offshore samples are slightly coarser and would probably be well suited 



83 



