S = (φ84 - φ16)/2
(21)
Figure 84 provides a fill factor that specifies the amount of fill material needed to produce a given
volume of in-place material. The axes are defined in terms of the mean particle size of the borrow (fill)
and native (in-place) material (Mb, and Mn), and the sorting of the borrow and native material (Sb, and
Sn). For instance, if Mb, = 3.0, Sb, = 2.0, Mn = 3.50 and Sn = 1.00; the fill factor from figure 84 is 1.2.
Therefore, if a beach containing 1,000 cubic yards of sand is desired, it will be necessary to initially
place about 1,200 cubic yards of sand from the borrow source.
Figure 85 illustrates the important design factors to consider when constructing a beach fill. The
berm elevation should be chosen to decrease the likelihood of overtopping by waves during storms. The
berm width is determined by geometry to provide for the volume of fill to be placed, or for the shoreline
use requirements. The beach slope should be chosen to parallel the existing profiles and slopes. This is
based on the assumption that the existing beach is in equilibrium with the wave forces and that the
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