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 City of Solana Beach
Section 3
Shoreline and Coastal Bluff Management Strategies Draft MEIR
Environmental Impact Analyses
the shoreline would again reach an equilibrium position, which would be very similar to the
existing beach profile. The shoreline would temporarily widen at locations up coast and
downcoast of the beachfill site, until natural littoral transport redistributed the sand along the
coast. Sand replenishment alone is not anticipated to significantly impact the littoral process.
Sand replenishment is anticipated to be performed in conjunction with a sand retention system
to increase the long-term effects of sand replenishment. Construction of jetties, groins, reefs,
breakwaters, or other sand retention devices (SANDAG, 2001b) that would be constructed to
aid in retaining the sand in the area of beach replenishment would not have significant negative
impacts on the geologic environment. Artificial sand retention devices such as breakwaters and
reefs would impound sand behind the structure. Groin fields could cause potential downcoast
erosion since the littoral drift is interrupted, resulting in significant impacts (SANDAG 2001b).
These structures could cause damage to existing reefs and disrupt surfing breaks.
This alternative would not be significantly impacted by geohazards such as ground rupture,
earthquake shaking, slope failure, flooding, or tsunamis. On the contrary, sand replenishment
would aid slope stability, reduce bluff/soil erosion, reduce tsunami effects, and reduce the
potential for slope failures by reducing erosion at the bluff toe and thus reducing erosion of the
overlying terrace materials.
Because the littoral processes within the Oceanside Littoral Cell dominate a large region of the
coast, any changes to beaches in the vicinity of Solana Beach would be relatively insignificant to
the entire cell. Previous placement of fills on the beach in Oceanside have not shown dramatic
changes in the littoral process. Since 1955, over 13,000,000 cubic yards of fill have been
placed onshore or nearshore in Oceanside by the USACOE with no adverse impacts having
been recorded (U.S. Department of the Navy, 1997). A sand berm would be expected to form in
the shallow subtidal area as a result of sediment transported into this zone, which would likely
improve surf break conditions. Scarping could occur during times of high waves. This could
cause minor changes in wave breaking characteristics and slightly increased wave energy
reflection during times of low waves (approximately 2 to 3 feet or less). However, this change
would be negligible and considered insignificant. In addition, sand deposition is not expected to
affect existing reef breaks in the area. Significant impacts to littoral processes would be
anticipated to occur as a result of this alternative.
Mitigation measures to offset the impoundment of sand behind breakwaters and reefs would
include pre-filling the area behind the retention structure (salient volume) with sand imported
from outside of the littoral system. Pre-filling the groin field, extending sand bypassing, regular
beach monitoring, and possible sand replenishment would mitigate downcoast erosion caused
by groin fields.
Project No. 323530000
Page 3-26
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