Inlet amounts to 34.5 million cubic yards for initial restoration and 50 

 years of nourishment. Of this total, about 12 million cubic yards may 

 be furnished by sand bypassing at Canaveral Harbor (USCE, 1967); the 

 remainder must come from borrow sources. 



Figure 22 shows the median diameter of sand on the beaches and in 

 the nearshore area. Figures 23 and 24 show typical beach material from 

 the study area. In general, the data indicate that desirable borrow 

 material for projects in the area should have a median diameter in the 

 range 0.3 to 0.5 mm (1.74 to 1.0 phi) and contain the same size classes 

 as the original beach material. 



3. Suitability 



Sand from beaches bordering the study area is not closely similar 

 to any sediment found in the offshore surface or subsurface deposits 

 (Appendix B) . Type A sediment is the closest in character to the beach 

 deposits, but significant differences between the two exist. Generally, 

 the beach sands are better sorted and more quart zose than those found 

 offshore in the study area. Quartz content of several midtide samples 

 from the area is around 65 percent compared to 20 to 30 percent or less 

 in offshore surficial sediments. Shell fragments which are important, 

 but not dominant, constituents of the beach sediment are mostly finely 

 broken, well rounded and polished. Beach drift shells collected near Fort 

 Pierce Inlet contained many thick-walled pelecypods such as Area zebra , 

 Noetia ponderosa and Glycymeris . Such species are probably well repre- 

 sented in the shell fraction of beach sands since the thick walls provide 

 sizeable grains resistant to fine fragmentation. Thin walled shells 

 readily break down into fine fragments under the vigorous regimen of the 

 littoral environment. 



Because the offshore potential borrow sands contain significantly 

 more shell material than the adjacent beaches, it is important to know if 

 this material is likely to break up into fine fragments under wave attack 

 on the beach face. For Type A sediment - and this is the only well-suited 

 fill material - the probability is that most of the shell fraction will 

 withstand wave attack on the beach as well as do the shell fragments in 

 the existing beach material. The major shell constituent of Type A sedi- 

 ment is the barnacle plate which appears to be resistant to mechanical 

 degradation, especially in comparison to algal material such as Halimeda 

 found in abundance in the Miami area. 



Species of Area , and large speciments of Crepidula should also pro- 

 vide suitable sand fragments, while more friable materials such as the 

 shells of Anomia simplex , may be soon lost from the sand fraction. It is 

 estimated that on the whole. Type A sediment should not initially lose 

 more than a small fraction of its sand-size material due to abrasion, and 

 that the remaining material will not degrade at a greater rate than the 

 existing beach sand. 



51 



