Quantcast COMPACTABILITY/MOLDABILITY OF PROPOSED BEACH FILL

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Coarser sands typically remain on the beach longer and therefore provide wider beaches than
finer sands. Coarser sands are often considered better for use as beach fill because of the
improved protection and retention characteristics they provide for the cost incurred. Coarser
sands will also form steeper equilibrium beach slopes at receiving beaches than finer sands. Steep
beach slopes can be considered less desirable than flatter beach slopes by some user groups, but
they generally do not create other types of adverse conditions. BEACON proposes use of beach
fill material that meets grain size criteria, as discussed in detail in Section 4.0 of this report.
2.3
COLOR
Resource agencies have been less concerned about material color in the past because of more
extensive use of dredged material for historic beach fill rather than upland material. Dredged
material typically is a darker color than the receiving beach initially, then is washed and
reworked by waves and eventually "bleaches out" under exposure to the sun and marine
environment resulting in sand very similar in appearance to the receiving beach. Resource
agencies have informally indicated that the only criteria for color is to reasonably match the color
of the receiving beach after reworking by waves for aesthetic reasons. Strong public reaction
occurred when red-colored sand was placed over the white sand beach at Ponto Beach in
Carlsbad, California in 1996.  Responsible agencies wish to avoid an unnecessary public
controversy. The CCC has conditioned approval of a beach fill project in Seal Beach in the past
on determination of the suitability of materials based on criteria defined in a Sand
Characterization Study (Moffatt & Nichol Engineers 1994). The study indicated that beach fill
material should possess similar sediment grain size and color as the receiving beach.
2.4
PARTICLE SHAPE
Use of natural sand rather than manufactured sand is considered more appropriate for beach fill.
Natural sand consists of rounded particles rather than sharp or angular particles. Natural sand is
carried downstream in rivers where fluvial transport causes wearing and rounding of particle
edges through abrasion.
2.5
DEBRIS
It is assumed that opportunistic sand will be free of trash and debris when placed on the beach.
Debris content should be addressed considering the source location of material and past land uses
on and around the site. Debris should definitely not constitute any substantial portion of beach
fill because of possible health and safety hazards posed by such materials and the possible
nuisance odors and visual impacts associated with their presence. Debris should be separated
from the sand at the source. BEACON proposes to visually determine whether debris screening
the material is necessary, and if so, to screen it at the source location as discussed in Section 4.0
of this report.
2.6
COMPACTABILITY/MOLDABILITY OF PROPOSED BEACH FILL
The behavior of beach fill under repeated wetting and drying conditions if placed high on the
subaerial beach above the reach of the tides, and after becoming semi-compacted during
placement is important in determining material suitability. Material that does not tend to harden
2-2
Moffatt & Nichol Engineers



 


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