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 City of Solana Beach
Section 3
Shoreline and Coastal Bluff Management Strategies Draft MEIR
Environmental Impact Analyses
Long-term Effects
No-long-term effects to geology and soils would result from the construction of cobble berms. In
the long-term (100+ years) with or without cobble berms, the ultimate landward erosion of the
bluffs is inevitable. The rate of landward erosion will depend upon varying factors such as the
beach width, cliff strength, and unpredictability of wave and tide conditions.
Effects of Cobble Berms on Coastal Upper Bluffs
No negative effects on coastal upper bluffs would result from the construction of cobble berms.
Cobble berms reduce the effects of wave and tide energy on the existing notches, therefore
reducing the potential failure of the upper bluffs in the short-term.
Summary
There are no known unique geologic features of unusual scientific value (such as fossils, etc.)
that cannot be found in adjacent geologic environments that would be adversely affected by the
construction of seawalls, notch/seacave in-fillings, or placement of revetments, etc. Protective
structures will not significantly cause major landsliding or erosion nor substantially alter the
existing topography. The majority of short-term and long-term effects are not considered
significant. However, the long-term loss of beach width and end scour effects of a completely
armored coastline are considered significant. The overall "geologic character" of the lower bluff
(seacaves, seepage areas, concretions, cross-bedding, geologic structure, etc.) would be
adversely affected and covered from view.
Impacts of geohazards (seismicity, fault rupture, liquefaction, settlement, etc.) on shoreline
protection structures or on public safety would be less than significant because they would be
mitigated by the project design as discussed below. Future seawalls and other protective
structures would not be adversely affected by soil liquefaction if they are properly engineered
and founded into formational materials. The potential for ground rupture is not considered
significant. The walls should be properly designed for flooding and tsunami effects. Shoreline
protective devices are designed to consider the potential for slope instability and these devices
should reduce the potential for future soil erosion or landsliding by reducing the undercutting or
"notching" of the Torrey Sandstone. This reduces the potential for failure of the overlying
terrace materials that may eventually adversely affect the residential structures or other bluff top
improvements, and public safety. The effects of significant geohazards will be mitigated by
design of the shoreline protective structures in accordance with the current standard of care in
the industry, the standards of the Structural Engineers Association of California, and the latest
edition of the Uniform Building Code (which specifies a seismic design to withstand an
earthquake event that has a 10 percent probability of exceedence in 50 years).
Continuation of the Shoreline and Coastal Bluff Protection Ordinance promotes the
implementation of seacave plugging and filling over the construction of seawalls, bluff retaining
walls, gunite covering, and similar permanent armoring for shoreline protection. This
alternative, therefore, reduces the long-term geologic and soils impacts associated with
Project No. 323530000
Page 3-22
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