4.4 Biological Resources
Alternative 1
4.4.2
This impact analysis is separated into receiver sites and borrow sites and for each of those locations,
impacts are addressed in terms of direct and indirect. The receiver sites have been designed so that the
sand replenishment footprints would not result in significant direct impacts to biological resources. The
greater potential for significant impacts occurs from the indirect effects of sediment transport where sand
deposition may have long-term effects to sensitive resources.
Impacts of Alternative 1a
Receiver Sites
Sand replenishment at the receiver sites would directly impact marine life by burying organisms within the
footprint of the fill. Indirect impacts would occur from turbidity generated during construction of the
receiver sites, migration of sand away from the site via natural transport processes up and down the coast,
mechanical disturbance associated with grading the slope of the fill, and construction noise disturbance.
The complete analysis is contained in Appendix D and summarized below.
Direct Impacts of Sand Placement
Construction of the beach receiver sites would result in burial impacts to marine biota. During beach
nourishment, large volumes of sand are placed above and throughout the intertidal zone. The amount of
sand overburden varies in thickness across the footprint of the fill. From the back beach to the top of the
slope, where sand depths would be deeper, all benthic organisms would be smothered. Organisms also
would be buried under decreasing depths of sand towards the toe of the slope and outside edges of the fill.
Past studies of dredge material disposal have demonstrated that some mobile organisms such as clams and
worms are capable of burrowing through deposited materials of one to three feet in thickness. Some
crustaceans such as amphipods and decapods also may escape burial at the leading edge of deposition.
Therefore, not all benthic organisms would be expected to die within the receiver site footprint, particularly
near the edges of the fill.
The loss of benthic organisms within the receiver site footprint is an expected and unavoidable impact
during beach replenishment projects. However, due to the adaptability of organisms within this sandy
Page 4.4-2
Regional Beach Sand Project EIR/EA
99-69\SANDAG EIREA 4.1 to 4.13.wpd 7/17/00
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