HomeMy WebLinkAboutPA2022-167_20211220_Coastal Hazards Evaluation / Geologic Stability ReportMr. Scott Schwartz December 20, 2021
2050 East Oceanfront Project No. 1-1201
Newport Beach, CA 92661
Subject: Coastal Hazards Evaluation / Geologic Stability Report
Proposed New Residence Construction
2050 East Oceanfront
Newport Beach, California
References: See attached List of References
Dear Mr. Schwartz,
In accordance with your request and authorization, G3SoilWorks, Inc. (G3), has prepared this
coastal hazards evaluation and geologic stability report summarizing our findings and
assessment of potential coastal hazards that could impact the proposed development at the
subject address. The purpose of our work, as concerned by this report, was to identify and
address coastal hazards and related geologic hazards potentially affecting the site / proposed
development over the next 75 years, including the potential for future erosion, flooding /
inundation, wave run-up, sea level rise, earthquake-induced liquefaction, and other related
hazards. The primary focus of this report is the assessment of coastal hazards potentially
affecting the geologic stability of the site / proposed new residence. Review and comment
regarding geologic hazards affecting the site / proposed development are addressed herein with
reference to our preliminary geotechnical investigation / engineering geologic evaluation report
for the project (Reference No. 1).
PURPOSE / INTENT
This coastal hazards evaluation and geologic stability report has been provided to satisfy, in
part, City of Newport Beach Municipal Code (Title 21 - Local Coastal Program Implementation
Plan, Sections 21.30.015.E.2 and 21.30.015.E.4; Reference No. 2), Supplemental Materials
Checklist (Reference No. 3) for Coastal Development Permit (CDP) application, and the City of
Newport Beach’s Local Coastal Program (LCP) which went into effect on January 30, 2017 with
approval by the California Coastal Commission (CCC). Per Appendix A of the City’s LCP
Implementation Plan (Reference No. 2):
2.8.3-1. Require all coastal development permit applications for new development on a beach or
on a coastal bluff property subject to wave action to assess the potential for flooding or damage
from waves, storm surge, or seiches, through a wave uprush and impact reports prepared by a
licensed civil engineer with expertise in coastal processes. The conditions that shall be
SoilWorksG
GEOLOGY GEOTECH GROUNDWATER
3
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Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
considered in a wave uprush study are: a seasonally eroded beach combined with long-term (75
years) erosion; high tide conditions, combined with long-term (75 year) projections for sea level
rise; storm waves from a 100-year event or a storm that compares to the 1982/83 El Nino event.
In addition to the above, supplemental reporting of geologic stability has been included
addressing geologic hazards associated with earthquake / seismic hazards, liquefaction /
ground settlement, shoreline erosion / stability, and other factors affecting long-term stability of
the site and proposed development – based on the findings and recommendations presented in
Reference No. 1.
SCOPE OF WORK
The scope of work for this coastal hazards evaluation and geologic stability report included:
Identification and evaluation of coastal hazards including the potential for future erosion,
flooding / inundation, wave run-up, sea level rise, tsunami / seiche, liquefaction / lateral
spread, and other related hazards;
An analysis of historic, current, and foreseeable erosion, including changes in shore
configuration and sand transport;
An analysis of the following conditions:
o A seasonally eroded beach combined with long-term (75-year) erosion;
o High tide conditions, combined with long-term (75-year) projections for sea level
rise; and
o Storm waves from a 100-year event or a storm that compares to the 1982/1983
El Niño event.
An evaluation of sea level rise and coastal flooding hazards projected over the next
75 years utilizing various sources of information including the State of California Sea
Level Rise Guidance document (Reference No. 4), USGS Coastal Storm Modelling
System for southern California (CoSMoS 3.0; Reference No. 5) and Our Coast Our
Future interactive mapping website (Reference No. 6, City of Newport Beach – Public
Trust Lands Sea Level Rise Vulnerability Assessment (2019; Reference No. 7);
University of California Irvine’s online Flood Hazard Viewer for Newport Bay (FloodRISE;
Reference No. 8); The U.S. Geological Survey’s National Assessment of Shoreline
Change Part 3 (Reference No. 9); FEMA’s local Flood Insurance Rate Map (FIRM,
Reference No. 10); and other publically available sources of information;
Review and comment regarding the site’s current geologic stability and that anticipated
over the next 75 years based on the proposed new residence structure and associated
foundation improvements – using the findings / conclusions of Reference No. 1 as a
basis.
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Newport Beach, California
An evaluation of the project’s impact on coastal resources, considering the influence of
sea level rise over the life of the project – including public access and recreation, coastal
habitat, water quality, archaeological/paleontological resources and scenic sources.
SITE LOCATION / DESCRIPTION
The subject property is located near the eastern end of Balboa Peninsula and southwesterly of
the intersection of M Street and East Oceanfront in the City of Newport Beach, California
(Figure 1, attached). The site is part of a relatively narrow, beachfront, residential lot
approximately 40 feet wide by 80 feet long and 3,184± square feet in area (Reference No. 12).
An approximately 20-feet-wide alleyway bounds the site to the north; existing residences bound
the site to the east and west (2054 and 2046 East Oceanfront, respectively); and Balboa Beach
bounds the site to the south. Existing site grades (according to Reference No. 12) range
between approximately 12.5-19± feet above NAVD 88 (North American Vertical Datum of 1988).
The site is located approximately 400± feet inland of the Pacific coastline and 1000± feet
westerly of West Jetty View Park and the inlet / outlet channel of Newport Harbor.
An existing 1980s-era, two-story, single-family residence with subterranean / split-level garage,
bathroom, and laundry room currently occupies the site. Figure 2 is included as an attachment
and shows the generalized configuration of the residence with respect to the garage (shown in
gray), front entryway (blue), and rear living room (green). Based on review and interpretation of
survey mapping by Apex Land Survey (Reference 12) and measurements taken onsite, the
garage, laundry room, bathroom, and storage area Finish Surfaces (F.S.) appear to be at
approximately Elevation (El.) 11± feet above NAVD 88; F.S. for the front entryway and rear
living room appear to be at El. 18± and 19± feet, respectively. The beach fronting the southerly
rear of the property (El. 18± feet) is approximately 5± feet higher than the driveway fronting the
alleyway / East Oceanfront to the north (El. 13± feet). Existing Grades (E.G.) along the
centerline of the existing alleyway slope east-southeast from El. 12.80 feet to El. 12.69 feet
(0.11 feet) over a distance of approximately 40 feet (slope (S) = 0.00275 vertical feet per
horizontal foot; S = 0.00275 ft/ft).
The existing garage occupies approximately half of the existing residential footprint and is
approximately 2.3± feet below the adjoining driveway. A relatively steep, concave- / convex-
sloped, interior driveway provides access to the existing sub-level garage and associated
laundry / bathroom / storage areas. An existing Concrete Masonry Unit (CMU) retaining wall is
located at the rear of the garage and is approximately 8-feet-high, with adjoining easterly and
westerly retaining walls that retain soil to within approximately 3 feet of property line. Existing
retaining wall heights along the east and west side of the property vary between approximately
3-9± feet and 7± feet in height, respectively. The existing living room and front entryway are at
least partly supported by retained soils and existing slab-on-grade construction.
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Newport Beach, California
PROJECT DESCRIPTION / PROPOSED DEVELOPMENT
Overview
Current plans provided by the Project Architect indicate that the existing residence is to be
demolished and replaced with a new two-story, single-family residence with basement-level
garage, driveway, recreational room, powder room, laundry, and storage closet. Preliminary
sections indicate that the Basement Floor is to be set at El. +7.35 (NAVD 88), requiring
excavations down to El. +4.00 or approximately 9 feet and 13-14 feet below the existing front
driveway and rear patio / beachfront, respectively. The first-story Living Room and Kitchen floor
levels will be set at El. +16.37 and will be adjoined at the southerly rear by a depressed Front
Yard at El. +15.99. Engineering geologic / geotechnical considerations for the proposed
development include:
Demolition of the existing residence and sub-level retaining walls;
Temporary shoring installation and below-grade excavations along property line;
Foundation construction including mat slab and basement retaining walls;
Shallow groundwater occurring at depths of approximately 4-13 feet below existing site
grades;
Mitigation of seismic hazards including liquefaction and seismic settlement;
Possible coastal flooding hazards associated with long-term sea level rise, astronomical
tides, storm activity, wave run up, and tsunami hazards.
The major factors listed above are addressed herein based on the findings of our geotechnical
investigation and engineering geologic evaluation of the project. The major geotechnical factors
involve below-grade excavations and construction of the proposed basement / garage level and
mitigation of issues related to shallow groundwater intrusion, moisture / vapor mitigation, and
earthquake-related liquefaction / dynamic settlement. Coastal hazards and related
considerations affecting long-term stability of the site are also important factors addressed
herein.
SURFICIAL GEOLOGY / GEOMORPHOLOGY / SITE HISTORY
Pre-Development History (1896)
The project site is located near the “Wedge” of Balboa Beach and southeastern terminus of
Balboa Peninsula – approximately 4.8± miles southeast of the modern Santa Ana River
Channel, 400± feet inland of the Pacific Ocean / modern coastline, 1,000± feet westerly of the
Newport Harbor inlet channel, and 1,400± feet northwest of the Wedge and Newport Harbor
Jetty. Review of historic topographic maps dating back to 1896 (Figure 3, below) indicates that
the immediate vicinity of the site is part of the historic southeasterly terminus of Balboa
Peninsula – a late Holocene-age sand spit / bar / barrier beach created by the Santa Ana River
(SAR) and its interaction with the coastline. Throughout latest Holocene time (the last 2- to
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Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
3-thousand years or so) discharge of terrestrial sediments from the SAR and other local sources
along the coast have been transported by wave-driven longshore currents, littoral drift, and
wind-blown / eolian sedimentation, creating the coastal beaches of southern California.
Historically, the local vicinity of the site also appears to have straddled the intertidal estuary of
Newport Bay and its “natural” inlet at the southernmost end of the peninsula. Note that the
location of the site shown on Figure 3 is approximate and appears to indicate that the site is
likely located in an area previously occupied by a bar mouth and cross-cutting, intertidal
channels of the Santa Ana River / Newport Bay.
Figure 3. U.S. Geological Survey September 1896 Edition of the Santa Ana Sheet (1:62,500 Scale, 25-
foot contour interval) topographic map showing approximate location of project site (green bullseye) on
historic Balboa Peninsula, adjacent to Newport Bay (image from Google Earth overlay; site location is
approximate; north is up; not to scale; for illustrative purposes only).
Early Historic Development (1927)
Beginning in the late 1890’s / early 1900’s, the tidal mudflats of Newport Bay were dredged and
reconfigured to create Newport Harbor. Review and analysis of historic air photos indicates that
the site itself occupies ground that did not exist in 1927 (Figure 4, below) and was essentially
open-water just offshore of the peninsula. The ground that currently supports the site / vicinity is
understood to be comprised of littoral beach sand that accumulated following construction of the
Newport Harbor Jetty – forming the “Wedge” of Balboa Beach. In general, the southerly
terminus of Balboa Peninsula represents a quasi-natural / man-made, historic landform that was
created through a combination of naturally occurring coastal sedimentation processes (i.e.,
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Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
wave erosion and longshore drift), eolian / wind-blown sedimentation, and placement of man-
made fills that likely include soils dredged from the adjacent Newport Harbor inlet channel.
Evidence of man-made fills includes the presence of inferred / buried rip rap encountered in our
exploratory borings (B-1, B-2, and B-3) at depths of 11-14± feet below the existing residence
driveway at approximately El. -1 to +2 feet NAVD 88 (Reference No. 1). This inferred rip rap is
understood to be representative of imported materials (grouted boulders, rock aggregate,
concrete, etc.) used in the construction of the nearby Jetty and/or an inferred historic rail line. It
is possible that the rip rap was placed by accident and/or on purpose as part of a temporary
revetment intended to stabilize the shoreline following an apparent, possibly storm- and/or tide-
related scour event. This inference is supported by the appearance of an erosional scour and
deflection in the 1927 shoreline shown in yellow on Figure 4 (below). The inferred rail line also
appears to have been disrupted by the 1927 scour event. This rail-line likely facilitated transport
of raw materials (rip rap, cement, aggregate, concrete, etc.) to and from the Jetty during
construction, and may have been supported by materials of similar character, prior to being
scoured / inundated.
Figure 4. Historic Air Photo from 1927 showing site location (green bullseye) and shorelines from 1927
(yellow), 1935 (green), and the modern shoreline (red) which became established by approximately 1942.
Air photo was approximately georeferenced using Google Earth and is not to scale. North is diagonally up
and to the left, subparallel to the Newport Harbor Jetty (right-hand side of photo). All lines, limits, and
locations are approximate and for illustrative purposes only. Based on the above, the shoreline of Balboa
Beach near the site expanded southward by approximately 230± feet between 1927 and 1935, and an
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Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
additional 300± feet between 1935 and 1942. This expansion appears to coincide with the extension of
the Newport Harbor Jetty by as much as approximately 600± feet, forming the “Wedge” of Balboa Beach.
Early to Middle Historic Development (1932-1942)
Development throughout Balboa Peninsula (in the form of Balboa Avenue, intersecting cross-
streets, and sparse residential construction) is apparent as early as 1932. In 1935 (Figure 5,
below), development of Balboa Peninsula overall appears to have been underway, with various
cross-streets, side streets, and residential housing in place along Balboa Avenue. However,
development near the site, at the end of the newly established peninsula, appears to be limited.
By 1935, the shoreline nearest the project site appears to have expanded southward by
approximately 230± feet relative to 1927, creating at least part of the land that currently supports
the site / existing residence. Subsequent topographic mapping available from 1942 indicates
that the overall shoreline had expanded an additional 300± feet (Figures 4, above; Figure 6,
below) and became established relative to its modern configuration. An additional factor in
establishing the modern shoreline and local vicinity of Balboa Beach near the Wedge is the
inferred placement of dredged sand to raise the elevation of the beach fronting the rear of the
project site, elevating it as much as 8± feet higher (El. 18-19± feet) relative to other areas
throughout Balboa’s main stretch to the northwest, commonly at El. 10-11± feet NAVD 88.
Figure 5. U.S. Geological Survey September 1935 Edition of Santa Ana Sheet (1:31,680 Scale, 5-foot
contour interval) topographic map showing approximate location of project site (green bullseye) south of
Balboa Avenue and Newport Harbor (image from Google Earth overlay; site location is approximate;
north is up; not to scale; for illustrative purposes only).
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Newport Beach, California
Figure 6. U.S. Geological Survey September 1942 Edition of Santa Ana Sheet (1:62,500 Scale, 25-foot
contour interval) topographic map showing approximate location of project site (green bullseye) south of
Balboa Avenue and Newport Harbor (image from Google Earth overlay; site location is approximate; not
to scale; for illustrative purposes only). Shorelines from 1927 (yellow), 1935 (green), and the modern
shoreline (red) which became established by approximately 1942 are also shown. North is diagonally up
and to the left, subparallel to Newport Harbor Jetty.
Early to Middle Historic / Modern (1948-Present)
An air photo from 1948 (Figure 7, below) indicates that the site itself was previously occupied by
residential structure that has since been demolished and replaced by the existing residence
currently onsite (Figure 8, below). Based on our discussions with the current owners and limited
review of vintage architectural plans for the existing residence, it is our understanding that
demolition of the previous residence and replacement with the existing residence took place in
the early 1980s. In terms of shoreline development and change, the 1948 air photo appears to
show the site during a constructional phase of shoreline development that took place in May of
that year. Comparison of the modern shoreline configuration with that shown in Figure 7
indicates that the shoreline may have accreted / expanded southward by as much as 100± feet
in that season relative to the modern shoreline shown in Figure 8. In general, the modern
shoreline is understood to be relatively stable, but subject to similar advances and retreats
driven by astronomical tides, storm activity, man-made influences, and general fluctuations in
sediment load. The Wedge itself has formed within the groin of the Newport Harbor Jetty,
representing a zone of accumulation which is stabilized by longshore currents / sediment
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Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
capture, early establishment of the elevated beach and associated eolian deposits, and
placement of man-made fills, and shoreline protection / restoration practices.
Figure 7. Historic air photo from May 1948 showing site (green bullseye) occupied by a previous
residence structure. Shorelines from 1927 (yellow), 1935 (green), and modern shoreline (red) are also
shown. Note that shoreline in 1948 appears to be in a constructional phase, extending beyond the limits
of the modern shoreline which is located approximately based Google Earth aerial imagery dated
January 22, 2020. Residence shown in photo is understood to have been demolished in the early 1980s
and replaced by the existing residence currently occupying the site. North is up and to the left. All lines,
limits, and locations are approximate and for illustrative purposes only.
Figure 8. Google Earth image dated January 22, 2020 of existing residence site / vicinity with shorelines
as shown in Figure 9. Scale is approximate. North is up and to the left. All lines, limits, and locations are
approximate and for illustrative purposes only.
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Proposed New Residence Construction Project No. 1-1201
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Newport Beach, California
Local Geologic Units and Occurrence
According to geologic mapping by Morton and Miller (Reference No. 13; Figure 9, attached), the
site is shown as being underlain by Quaternary very young eolian deposits (Qe) and Quaternary
very young marine deposits (Qm) of late Holocene age. The eolian deposits are described as
being comprised of unconsolidated / fine-grained sand and silt derived from recently active,
coastal sand dune deposits occurring in the Newport Beach area; the marine deposits are
described as, “unconsolidated, active or recently active sandy beach deposits along coast”. In
general, for the purposes of this study, native sediments underlying the site are designated as
Quaternary beach sand (Qb), representing a combination of native eolian and marine deposits.
These soils intermingle with shallow / locally-derived / undifferentiated fills of similar character.
Fill soils, where present, likely occur in the upper 3-5 feet and are generally similar to / or
reworked from the local native beach sands.
The deposits directly underlying the site to depths of approximately 15-20± feet below ground
surface are understood to be historic, quasi-natural deposits of littoral sand and possible dredge
fills established during the early 1900’s during the development and expansion of Balboa
Peninsula and the Newport Harbor Jetty. An additional 5 to 6± feet of historic fills and/or native
eolian deposits are present at the rear of the property, accounting for the 5-6± feet higher
elevation difference between the north and south sides of the property and alleyway /
beachfront, respectively. Below these historic deposits are similar marine deposits of littoral
sand and shell hash deposited during the early to middle Holocene and perhaps latest
Pleistocene (when sea level was significantly lower), extending to depths of at least 50 feet.
HYDROGEOLOGY / GROUNDWATER
General Hydrogeologic Overview
Soils underlying the site are understood to consist of Quaternary-age beach sand to depths of at
least 50 feet or more, with groundwater occurring at depths of approximately 4-13± feet below
existing site grades. Groundwater is unconfined and understood to be essentially salty (saline)
ocean water. Based on previous subsurface investigations for the site and other neighboring
sites, there are understood to be no confining layers (aquicludes / aquitards) below the site to
depths of at least 50 feet. Groundwater below the site is understood to be in open-
communication – vertically, horizontally, locally, and regionally – with the Pacific Ocean and
Newport Harbor. This communication is facilitated by the presence of relatively continuous, sub-
horizontally layered, moderate- to high-permeability, fine- to medium-grained and locally coarse-
grained sand horizons / lenses that comprise the native soils of Balboa Peninsula.
Groundwater Levels / Fluctuations
Tidal fluctuations of the Pacific Ocean and Newport Harbor affect groundwater levels by
inducing hydraulic gradients toward the ocean/harbor and away from the site during low tide
conditions, and away from the ocean/harbor and toward the site during high tide conditions. Our
recent groundwater monitoring for the period of June 21st, 2021 through December 10th, 2021
indicates that groundwater elevations range between approximately +4.5 to +6.7 feet
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Newport Beach, California
(NAVD 88) following low-low tide (e.g., -1.2 feet) and high-high tide conditions (e.g., +6.0 feet),
respectfully. However, actual groundwater levels may vary slightly from these estimates due to,
among other things, apparent changes caused by barometric pressure variations over the
monitoring period, which can introduce errors generally on the order of no more than about 0.1
feet and not more than about 0.3-0.4 feet (the upper bound range of variability in atmospheric
pressure over the entire monitoring period). A graph summarizing our observations and
recorded water levels over the monitoring period is attached as Figure 10 and we note that our
manual water level readings were within 0.1 feet of the water levels predicted based on the
transducer data, tied to the different manual readings. For planning purposes, water levels may
be expected to vary between approximately +5 and +7 feet above NAVD 88 – conservatively
accounting for possible measurement errors caused by barometric pressure variations which
would affect the transducer data. It should also be noted that these estimates are based on
limited data obtained during the above referenced monitoring period and actual levels may
occur outside the range reported. Nonetheless, the estimates provided herein are considered
reasonable relative to the available data and intended use.
COASTAL HAZARDS EVALUATION
Regional Oceanographic Setting
Areas of the Pacific Ocean to within approximately 100-150 miles offshore of the southern
California coastline (i.e., southern California bight) occupy California’s Continental Borderland –
a major geomorphic province extending over 200 miles from the Santa Barbara coastline and
Channel Islands, southeast to near the mouth of the San Diego River and La Jolla Submarine
Canyon (Reference No. 11; see Figure 11, below). The Continental Borderland forms a unique
submarine environment with complex bathymetry including deep basins / escarpments,
intervening seamounts, continental shelves at various levels, islands, submarine canyons, and
major northwest-trending fault lines. These bathymetric features have a profound influence on
the development of ocean currents and swells generally approaching the bight from the west /
northwest and south / southwest. The Channel Islands generally shield the southern California
bight from approaching waves / swell, limiting storm wave heights relative to the open coasts of
central and northern California. This shielding and interaction with ocean swells causes them to
refract and reflect off the islands and offshore / nearshore bathymetry, resulting in a
predominantly northwest to southeast, wave-generated littoral current. These littoral currents
result from long-term cycles of wave run up and erosion interacting with the various beaches
and deltas / river systems that serve as sources of sediment. Sediments transported by these
littoral currents ultimately migrate toward the various submarine shelves, canyons,
escarpments, and deep ocean basins. Intervening basins created by the various northwest-
trending fault lines within the Borderland range in depth from 3-thousand feet to greater than
6-thousand feet. Along the southwesterly edge of the Borderland, the continental slope
descends toward the abyssal plain to depths greater than 12-thousand feet.
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Newport Beach, California
Figure 11. Annotated Google Earth image of Continental Borderland showing its relief / bathymetry.
Project site is labeled and shown with green bullseye.
As shown on Figure 12 (below), the offshore areas adjoining the modern coastline are
subdivided into individual segments or “compartments” where littoral sediments (mainly beach
sand) in the nearshore region are generated from local source areas (e.g., streams, rivers,
eroding bluffs, beaches), transported by longshore / wave-generated currents within the swash
zone / nearshore, and deposited locally within shallow continental shelf areas and/or into deep
submarine canyons, both of which act as regional “sinks” for littoral sediment. These
compartments are also referred to as littoral “cells” which are often bound to the north (i.e.,
“upcoast”) by rocky headlands and/or other physical submarine barriers or sinks which cut-off
sediment transport to the south or “downcoast”. Balboa and Newport Beach are part of the San
Pedro littoral cell (Reference No. 11) which extends approximately 42 miles southeast from
Point Fermin to Dana Point. The Huntington Beach littoral sub-cell comprises the northern
portions of the San Pedro littoral cell and is bound by the Palos Verdes Peninsula to the north,
San Pedro shelf to the south, and Newport Submarine Canyon to the southeast (Figure 13,
below). The Newport Submarine Canyon lies directly offshore and westerly of the site and is the
primary sink for littoral sediments deposited by the Santa Ana River and other local source
areas to the northwest.
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Newport Beach, California
Figure 12. Excerpted map from Reference No. 11 showing littoral cells (i.e., “compartments) of southern
California’s Continental Borderland. Note that the site (red square) is located near the southerly terminus
of the San Pedro littoral cell (i.e., Huntington Beach littoral sub-cell) and Newport Submarine Canyon
which serves as its primary sink, southwest and offshore of the site. Wave-generated longshore currents
(represented by orange arrows) cause sediments within the littoral zone to migrate from the Palos Verdes
Peninsula, southeastward toward Newport Canyon.
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Newport Beach, California
Figure 13. Google Earth Image of northern San Pedro Littoral Cell / Huntington Beach Sub-Cell (Not to
Scale; For Illustrative Purposes Only). Longshore transport of littoral sand (orange arrows) is from
northwest to southeast. Major sediment sources include (from left to right) the Los Angeles, San Gabriel,
and Santa Ana Rivers (blue lines). Major sediment sinks include the San Pedro Shelf and Newport
Submarine Canyon, located southwest of the site. Site location is shown with green bullseye.
Local Beach Setting
The project site is an approximately 40 feet wide by 80 feet long, rectangular parcel and existing
residence structure within approximately 1,400 feet of the southerly terminus of Balboa
Peninsula and its “join” with the Newport Harbor Jetty, also known as the “Wedge” of Balboa
Beach (Figure 14, attached). As described in the surficial geology / geomorphology / site history
section of this report, the Wedge and southerly portions of Balboa Peninsula are quasi-natural /
historic landforms that developed during the early- to mid-1900s as a result of dredging
operations within Newport Bay and construction of the Newport Harbor Jetty. The Newport
Harbor Jetty extends approximately 2,000 feet south-southeast from the southerly tip of the
Peninsula and was constructed as a means of shoreline stabilization and artificial growth /
expansion. Littoral sand transported southeastward by longshore currents have accreted within
the groin of the Jetty, forming the Wedge and portions of Balboa Beach fronting the project site.
As a result, between 1935 and 1942, the shoreline of Balboa Beach expanded southward by as
much as 300± feet and the elevation of the beach was raised up to approximately El. 15-18±
feet (NAVD 88). The site sits at El. 18± feet along the beachfront and El. 13± feet adjoining the
alleyway to the north.
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The prevailing local climate is Mediterranean, with hot / dry summers and cool/wet winters.
According to the City of Newport Beach website, the area receives 10.8 inches of annual rainfall
on average, the majority of which falls between November and April. Storm activity is seasonal
with cooler, extratropical storms predominating during the winter months and warmer, tropical
storms occurring during late summer / early fall (Reference No. 15). Tides are mixed semi-
diurnal and consist of two high tides and two low tides of unequal size occurring each lunar day
(~24.8 hours). Spring tides (higher than average tides that occur when earth, moon, and sun are
aligned) occur approximately twice per month. Perigean spring tides (very high tides that occur
when the moon is at perigee and closest to the earth during a spring tide) occur approximately
3-4 times per year. Increased storm activity, wave heights, and west-northwest swell (from the
west-northwest) occur during the winter, while calmer weather, decreased wave heights with
longer periods, and south swell tend to occur during the summer. Because the shoreline of
Balboa Beach faces south-southwest, south swells (from the south) occurring during the
summer / fall months reportedly erode the beach more readily than the west-northwest swells
that occur during the winter. According to Reference No. 7, the beach tends to erode during the
summer and expand during the winter months, except when exceptional storm activity occurs –
this is the opposite of what typically occurs on most beaches, where shoreline erosion tends to
predominate during the winter, with widening during the summer. Regardless, the most severe
erosion is anticipated to typically occur between late fall and early spring, in response to
astronomical high tides and extratropical storm wave activity.
Vertical Datums and Tidal Range
The vertical datum and tidal station used in our coastal hazards evaluation is the North
American Vertical Datum of 1988 (NAVD 88) and National Oceanic and Atmospheric
Administration’s (NOAA) Los Angeles Tidal Station No. 9410660 (see Appendix A, attached). As
shown in Appendix A, use of NAVD 88 as the reference vertical datum (El. 0.00 feet) renders:
Mean Lower-Low Water (MLLW) at El. -0.2 feet;
Mean Low Water (MLW) at El. +0.74 feet;
Mean High Water (MHW) at El. +4.55 feet;
Mean Higher-High Water (MHHW) at El. +5.29 feet;
Mean Sea Level (MSL) at El. +2.62 feet;
Great Diurnal Range (GT) of 5.49 feet (i.e., MHHW minus MLLW).
Highest observed tide (i.e., Max Tide) for this station is +7.72 feet, measured on
January 10, 2005 at 1612 (Military Time).
Nearshore / Inshore Bathymetry and Beach Profile
Figure 14 shows bathymetric depth-counter soundings for the nearshore / inshore areas nearest
the site. Analysis of these contours indicates that offshore areas within approximately 800± feet
of the local shoreline slope approximately 4 percent (1:25; vertical:horizontal) or about 2.2-2.3
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degrees south-southwesterly (Azimuth: N201˚E). A localized cusp is apparent southwest of the
site and within approximately 500 feet of the shoreline with local gradients of about 6 percent
(1:16; V:H) or 3.5 degrees. This cusp may be a transient feature and/or associated with wave
refraction / reflection / interference phenomena occurring near the groin of the jetty, creating a
localized zone of accretion. Review of historic aerial imagery indicates this cusp may be a
persistent / quasi-permanent feature.
Figure 15 (below) shows a diagram of a typical profile for reference in describing the
generalized profile of the beach fronting the site. Beach profile gradients estimated within the
swash zone (i.e., foreshore) using Google Earth are estimated at 12-percent (1:8; V:H) or about
6.8-degrees within approximately 85 feet of the shoreline and between El. 0 feet to El. +10 feet.
Inland of the swash zone (i.e., backshore beach / berm), profile gradients steepen over a short
distance (approximately 15 feet) from El. 10± feet to El. 15± feet (33 percent slope / 18 degrees
/ 1:3 – V:H), creating a berm elevation 15 feet above NAVD 88 and more than 7 feet above
highest observed tide (+7.72 feet). Inland of this berm, the backshore beach flattens to
approximately 1 percent slope (0.6 degrees or 1:100; V:H) for a distance of approximately
300 feet to the rear of the subject property / existing residence. Horizontal distance between the
site and shoreline at El. 0 feet is estimated at 400± feet. The existing rear patio is at
approximately El. 18-19 feet above NAVD 88 and more than 10 feet above highest observed
tide.
Figure 15. Generalized diagram of a typical beach profile for reference in describing beach profile fronting
site. Note that site would be situated at rear of backshore beach.
Source: https://rwu.pressbooks.pub/webboceanography/chapter/13-1-beaches/.
Climate Change and Sea Level Rise
Global (Eustatic) Sea Levels and the Astronomical Theory of Climate Change
Sea level, in general and on a global scale, is controlled by the volume of water stored in earth’s
oceans relative to that stored on land, primarily as glaciers and continental ice sheets. Global
changes in sea level resulting from changes in the volume of water stored in earth’s ocean are
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termed “eustatic”. A major driver of earth’s climate is the sun and the intensity of solar radiation
reaching the northern hemisphere, which fluctuates over 20- to 100-thousand-year cycles (i.e.,
Milankovitch Cycles). Milankovitch cycles have occurred throughout Pleistocene time (the last
1-2 million years or so) and caused periodic shifts in earth’s climate as a result of changes in
solar radiation reaching the northern hemisphere, particularly at approximately 65˚ North
Latitude. Earth’s orbit around the sun, including the eccentricity of its orbit, the tilt of the earth’s
axis of rotation, and the wobble of earth’s axis over time, causes the climate to warm during
interglacial periods (when solar intensity and sea level is high) and cool during glacial periods
(when solar intensity and sea level is low). From a climate change perspective, these increases
and decreases in solar intensity represent direct inputs of heat / energy into earth’s atmosphere,
primarily as heat reflected from the earth’s surface. However, the actual timing and rates of
climatic change are complicated by numerous other factors, including:
The albedo or reflectivity of the earth’s surface and effects on solar insolation –
controlling how much incident light is reflected and transformed into heat within earth’s
atmosphere.
Polar regions covered in snow / ice are cold because they reflect light / short-wave
radiation back into space and transform very little into heat / long-wave radiation.
Tropical regions are generally warmer because much of the incident light is transformed
into heat and reflected back into the atmosphere as long-wave radiation / heat.
Circulation of ocean currents and rates of upwelling – moderating global climate by
promoting exchange of warm tropical waters with cooler extratropical and polar waters
Groundwater storage / withdrawal – effectively removing and/or adding water to the
atmosphere and earth’s oceans.
Growth / expansion of glaciers and continental ice sheets – increasing the albedo /
reflectivity of polar regions, decreasing the amount light converted into heat within the
atmosphere, and lowering sea level by removing water from earth’s oceans.
Shrinkage / melting of glaciers and continental ice sheets – providing the opposite effect
by warming the atmosphere and raising global sea levels by increasing meltwater
storage in earth’s oceans.
The effects of plate tectonic movements and volcanism – affecting the size and
distribution of earth’s land masses, oceans / ocean-currents, and releases of
greenhouse gases and light-blocking smoke and ash into the atmosphere by volcanism.
With regards to the above, earth has been in a relatively warm / interglacial period throughout
the Holocene (the past ~11,000 years of geologic time). Prior to that, during earth’s last glacial
maximum (20- to 24-thousand years ago), earth’s climate was colder and sea levels were
significantly lower (on the order of 100 m / 328 feet lower than today) as a result of glaciation
and the growth of continental ice sheets that blanketed the alpine regions and northern
hemispheric regions of the earth.
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Relative Sea Level, Isostatic Adjustment, and the Geoid
Sea level is not the same at all points on the earth’s surface because the earth is not perfectly
round – but an oblate spheroid with significant surface topography, variations in the density and
distribution of mass across its surface, and variations in the strength of the gravitational field at
any given location. Earth’s geoid is defined as the equipotential gravitational surface that the
earth’s oceans would theoretically rise to in the absence of tides, winds, currents, temperature
variations, etc. Earth’s geoid is not perfectly round and looks more like a lumpy or rotten orange
(Figure 16, below), meaning that local relative sea level and rates of sea level rise can vary
significantly at different locations across the earth’s surface. Additionally, the earth’s crust and
surface as a land-based reference-frame is subject to isostatic adjustments (subsidence and/or
uplift resulting from mass-loading and -unloading by glacial ice and meltwater, causing localized
deflection and/or rebound of the earth’s crust and underlying mantle). Furthermore, tectonic
movements and crustal deformation also have an effect on relative rates of sea level rise, as
tectonic uplift and subsidence can cause rates of sea level rise to appear larger or smaller than
eustatic. To illustrate these points, note that rates of relative sea level rise vary significantly from
one location to another along the southern California coast (see Figure 17, below). These
differences and apparent rates of sea level rise may be thought of net rates controlled by global
changes in eustatic sea level, local isostatic adjustment due to meltwater loading, and crustal
deformation (uplift / translation / subsidence) and tectonism – all of which are ongoing
processes that effect rates of local relative sea level rise.
Figure 16. Illustrative rendering of Earth’s geoid (left) showing how relative sea level and earth’s
gravitational field varies by as much as +80 m (red regions) to -100 m (blue regions) relative to the earth’s
reference ellipsoid (right; a mathematically derived, vertical datum approximating the earth’s surface as
an oblate spheroid / ellipsoid). Geoid heights are relative to the reference ellipsoid and approximate
relative sea level from one location to another. The relative sea level in southern California is shown as
being slightly depressed and on the order of 30 meters below the reference ellipsoid (light blue region in
upper left, along southwestern edge of North America). Sources of inset figures: https://eos-
gnss.com/knowledge-base/articles/elevation-for-beginners;
http://www.wdcb.ru/mining/Gps/Texas/datum.html.
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Figure 17. Excerpt from Reference No. 9 showing historic changes in monthly mean sea level for different
tide gauges and time intervals over the past century and a half. Note that monthly mean sea levels for the
Los Angeles tide gauge have reportedly risen 6 cm (~2.4 inches) between 1923 and 2000, implying a
long-term average rate of sea level rise of +0.84 mm/yr (0.0028 ft/yr), which is a relatively low rate
compared to +2.13 mm/yr and +2.15 mm/yr estimated for the San Francisco and San Diego tide gauges,
respectively. As described above, these differences are likely due to a combination of global eustatic sea
level rise, local isostatic adjustments, and/or local relative tectonic movements of the Earth’s crust.
Latest Pleistocene through Holocene Sea Levels
Earth’s climate has been warming and sea levels have been rising for the past 18,000 years or
so of geologic time. Melting of glaciers and continental ice sheets has increased the volume of
meltwater stored in earth’s oceans, causing global eustatic sea levels to rise as a result. The
opposite occurred approximately 20- to 24-thousand years ago, leading up to earth’s last glacial
maximum, when global sea levels were on the order of 100 meters (328 feet) lower than today.
Two (2) prior interglacial periods, Marine Isotope Stages (MIS) 5a and 5e, occurred
approximately 80- and 120-thousand years ago, respectively, and sea levels at these times are
estimated to have risen approximately 4.8 meters (~16 feet) and 15.1 meters (49.5 feet) higher
than today, respectively (Reference No. 16). Evidence of these and other previous interglacial
highstands of sea level are well documented by the flights of emergent marine terraces
(ancient shorelines / uplifted beach deposits) that span the coastal zone from San Diego to
Newport Beach (Reference No. 14). The 120-thousand year old terrace is well preserved along
the bluffs of Corona Del Mar at elevations approaching 75± feet above NAVD 88. This ancient
terrace is known to contain marine invertebrate fossils that originated in warmer, tropical waters
(Reference No. 14) – indicating that local relative sea level and average annual sea surface
temperatures were significantly higher than today. An illustration of the late Pleistocene through
Holocene sea level curve is included below as Figure 18.
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Figure 18. Illustrative graph of Late Pleistocene through Holocene Sea-Level Curve. Note that past
changes is sea level (right axis) are shown for illustration but are not specific to the California coastal
zone. Warm / interglacial periods of high sea level (odd numbered) are highlighted in blue. Cold / glacial
periods of low sea level (even numbered) are highlighted in yellow. Oxygen isotopes (O18; left vertical
axis) measured from fossil shells of foraminifera (planktonic, single-celled, marine organisms) serve as
proxies for global temperatures and sea level, indicating dramatic fluctuations over the past several
hundred thousand years of geologic time. For more information on these Pleistocene sea level
fluctuations along the southern California coast, refer to Reference Nos. 13-14. Source:
https://www.researchgate.net/figure/Eustatic-sea-level-curve-for-Late-Pleistocene-and-Holocene-Also-
shown-are_fig2_267769111.
Global Warming and the Theory of Man-Made Climate Change
Another factor which has been an ongoing topic of scientific discussion / debate, is the
contribution of greenhouse gases to earth’s climate and the effects of anthropogenic (man-
made) carbon emissions from the burning of fossil fuels. The fundamental premise of man-
made climate change theory is that atmospheric carbon (as carbon dioxide or CO2) is a
greenhouse gas and has been increasing in concentration as a result of burning fossil fuels over
the past 300± years. As a greenhouse gas, CO2 (along with water vapor, methane, nitrous
oxide, and ozone) absorb, emit, and retain heat within earth’s atmosphere, causing it to remain
warmer for longer periods of time. Water vapor is the most abundant greenhouse gas and the
earth is a very complex system with multiple sources and sinks for atmospheric carbon,
including earth’s rainforests, oceans, photosynthetic algae populating earth’s oceans, limestone
reefs, and a variety of other chemical / biological sources and sinks. It has been hypothesized
that the recent warming trend in Earth’s climate (reportedly +0.14 ˚F/decade since 1880 and
+0.32 ˚F/decade since 1981; Reference No. 17) is the result of anthropogenic carbon emissions
and resulting increases in atmospheric CO2 concentrations, which reportedly reached historic
highs of nearly 450 and 400± parts per million (ppm; Figure 19, below) in the early 1800s and
early- to mid-1940s. Other sources of information regarding historic CO2 concentrations include
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arctic ice cores (see Figure 19) which have also been used to estimate historic / prehistoric CO2
concentrations.
Figure 19. Graph excerpted from Reference No. 18 showing yearly average CO2 concentrations (red
dots), 5-year running mean concentrations (red line), and those estimated from chemical analysis of ice
cores (gray line / blue dots) obtained from northern hemispheric polar regions. Note relative temperature
is indicated by blue line and that ice core data does not reflect the variability indicated by actual
atmospheric measurements. CO2 concentrations are shown in the early 1800s and early- to mid-1940s
peaking at levels approaching 450 ppm and 400± ppm, respectively. Also note that current levels are
reportedly on the order of 400-420 ppm.
Future Sea Level Rise Projections
Based on the assumption that increases in CO2 are responsible for the current warming trend
and rise in sea level, there have been a number of attempts made to correlate atmospheric CO2
concentrations with historic sea level rise and projected future sea levels based on rates of
glacial meltwater influx and other factors effecting global / eustatic and local relative sea level.
Unfortunately, the earth and its oceans form a complicated system of feedback loops containing
multiple inter-related variables that operate in different ways on different time-scales, making
them extremely difficult to accurately model / predict. The complexities involved in modelling /
predicting future sea level rise introduces a relatively high degree of uncertainty in correlations
and correlation-based projections that rely on CO2 as the primary / controlling input. In fact,
Kopp et al. (2014; Reference No. 19) caution that the uncertainties in their projected estimates
of sea level rise are within the bounds of inter-annual variability in modern mean sea levels until
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about 2030-2050 – implying that the empirical accuracy of their models cannot even begin to be
assessed for at least another 20-30 years or more.
Estimated Local Rates of Historic Sea Level Rise
Throughout the Holocene (the last 11,000 years or so of geologic time), sea level has risen
rapidly as a result of being in a relatively warm interglacial period of earth’s climate. Sea level is
estimated to have risen about 100 meters (328 feet) since the end of the last ice age
(18,000 years ago), indicating an estimated long-term rate of 0.018 feet per year (ft/yr). It is
reported that between 1923 and 2000, monthly mean sea levels have risen approximately
6 centimeters in the Los Angeles coastal region (2.36 inches or 0.0026 ft/yr; Reference No. 9).
Another source (Reference No. 15) indicates an average rate of sea level rise of 0.0064 ft/yr or
about 4.7 inches total for the Orange County coastal region between 1925 and 1986. Yet
another estimate of relative sea level rise is indicated by NOAA for the Los Angeles Tide Station
No. 9410660 (Figure 20, below) at 1.03 ± 0.22 mm/yr (0.0034 ± 0.00072 ft/yr). As sea level
continues to rise, areas of low-lying coastal development are likely to become prone to coastal
flooding / inundation and/or permanently submerged and unserviceable. If the recent trends
were to continue, sea level could potentially rise by 0.2-0.5 feet over the next 75 years – such a
rise in local relative sea level would have a negligible impact on the site / proposed development
due its elevation at 13-18± feet above NAVD 88.
Figure 20. Graph of monthly mean sea level trends with the average seasonal cycle removed. Note that
rate of sea level rise from about 1923 to 2020 is estimated at 1.03 mm/yr (0.0034 ft/yr) or about 0.34 feet
(3.8 inches) per 100 years.
Source: https://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?id=9410660.
State of California Sea Level Rise Guidance Document
The State of California’s 2018 Sea Level Rise Guidance Document (Reference No. 4)
recommends the use of probabilistic projections of sea level rise occurring over the next 75+
years based on a spectrum of hypothetical risk scenarios (Figure 21, below). As shown on
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Figure 21, sea level rise projections (shown in feet) are provided for the Los Angeles region for
low and high emissions scenarios leading up to the year 2100. Using the project’s design life of
75 years, sea level rise projections for the year 2100 are considered herein as conservative to
very conservative estimates of potential sea level rise occurring over the next 75 years. For “low
risk” and “medium to high” risk aversion scenarios with 66- and 0.5-percent probability of being
exceeded, sea level rise projections range from 2.1-3.2 feet up to 5.4-6.7 feet by the year 2100,
respectively. In terms of elevation, this would translate to sea levels rising between El. +2.1 to
+3.2 feet (NAVD 88), and possibly as high as El. +6.7 feet by the year 2100. Interpolating this
range of values for the year 2096 yields sea level rise estimates of 2-3 feet, and possibly as
high as 6.1 feet over the next 75 years. In terms of annual rates, these estimates range from
0.02-0.04 ft/yr (low risk aversion scenario) up to in excess of 0.08 ft/yr (medium – high risk
aversion scenario) – rates that are 4- to 6-times and up to 12.5-times the historic rate of
0.0064 ft/yr estimated for the Orange County coastal region over the 61-year period of
1925-1986 (Reference No. 15).
Figure 21. Excerpt from Reference No. 4 showing decadal (10-year) sea level rise projections for the
Los Angeles coastal region through the year 2100. Note that upper-bound estimates based on the “low
risk” and “medium – high risk” aversion scenarios for the year 2100 (red boxes) and preceding decade
(2090) were interpolated to determine sea level rise projections for the year 2096, based on a 75-year
design life for the project / proposed development.
Site-Specific Sea Level Rise Hazard Assessment
Current site elevations range between El. +18 feet near the rear / south side of the property
(fronting the beach) and +13 feet at the front / north side of the property (fronting the alleyway).
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Considering the highest observed tide of +7.72 feet for Los Angeles Tidal Station No. 9410660,
high-high tide sea levels in the year 2096 could rise to elevations ranging from approximately
+9.7 feet to +10.7 feet, to possibly as high as +13.8 feet. Given the current site elevations (+13
to +18 feet), highest observed tide, and probabilities reported in Reference No. 4 for sea level
rise projections over the project’s design life (75 years), there is reportedly a 66-percent
probability / 2-in-3 chance or better that sea level plus high-high tide conditions will remain
below existing site elevations. Based on the medium to high risk aversion scenario, there is
reportedly a 0.5-percent 1-in-200 chance that sea level plus high-high tide conditions could rise
above the elevation of the existing driveway / north side of property fronting the alleyway.
However, the science of climate change and sea level rise is still evolving and a subject of
ongoing research, particularly with regards to the influences of man and carbon emissions.
Given that, the sea level rise projections provided in Reference No. 4 are considered
conservative guidelines when compared to the observed rates of monthly mean sea level rise
reported over the past century (i.e., 0.0026-0.0064 ft/yr). The most vulnerable portions of the
site / proposed new residence would be the portions of the site fronting the alleyway which is
currently at approximately El. 13± feet. Nonetheless, the project site is located and elevated
favorably relative to most other areas along Balboa Peninsula and is considered reasonably
safe from inundation due to sea level rise and high tide conditions over the project’s design life
(75 years).
Coastal Erosion and Wave Attack
General Overview
Coastal erosion and wave attack primarily occur as a result of high surf / storm activity and/or
sediment starvation, and operate on time-scales that are acute, seasonal, and long-term in
nature, resulting from individual storms, seasonal variations in wave climate, and resulting
changes in shoreline configuration. Winter storms typically generate the highest surf and tend to
be more erosive, increasing rates of longshore drift, seasonal erosion, and nearshore bar
development. Sediment load is controlled by a number of factors including artificial beach
nourishment, sediment discharge from the Santa Ana River and other streams / rivers to the
north, and influx of sediments generated by bluff erosion. Rivers contribute the majority of sand
to California beaches and sediment delivery / influx by rivers is episodic, with sediment
discharge from a single year of extreme flood conditions potentially exceeding decades of low or
normal flow (Reference No. 11). In the absence of meaningful / significant river / sediment
discharge (e.g., during periods of prolonged drought), beaches can become “starved” and
recede as seasonal storm / wave activity strips sand from beaches and delivers it to regional
sinks like the Newport Submarine Canyon offshore and southwesterly of the site.
The site itself is fronted to the south-southwest by Balboa Beach, which typically is on the order
of 300-400 feet wide under historic conditions. The profile of the beach fronting the site is such
that there is usually a 300± feet wide, elevated fore-edge berm and backshore beach buffer
between the site and active swash zone (i.e., foreshore). This backshore buffer is elevated by
as much as 7-10± feet above the highest observed tide (+7.72 feet; Appendix A) and is a
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relatively stable feature ranging in elevation between approximately +15 feet and +18 feet
above NAVD 88. Within the foreshore / active swash zone, the beach is subject to tidal
fluctuations and wave attack which can encroach inland into the backshore region under
extreme tides with exceptionally high surf conditions. The Newport Harbor Jetty also plays a
significant role in focusing wave energy near its groin and creating localized zones of erosion
and accretion.
Regional / Local Rates of Shoreline Change
As shown on the attached excerpt (Figure 21, below), rates of shoreline change within the San
Pedro Cell are variable but appear to indicate overall stability of shoreline areas north of West
Newport Beach, with net long-term shoreline growth / accretion estimated at 0.5 m/yr
(1.64 ft/yr). According to Reference No. 9, this observed shoreline growth / accretion is
attributed to beach nourishment programs implemented to offset reduced sediment supply from
the Los Angeles, San Gabriel, and Santa Ana Rivers. West Newport Beach, however, appears
to be locally affected by the Newport Submarine Canyon, which serves as a major sediment
sink marking the southern terminus of the northern San Pedro Littoral Cell / Huntington Beach
Sub-Cell. Sediment loss and coastal erosion appears to be most pronounced near the west end
of Newport Beach (northwest of the Newport Beach Pier), which tends to be a focus of wave
attack by south, west, and southwest swells refracting off Newport Canyon, as well as tide-
related, submarine currents which likely remove sediment from the littoral system offshore of the
Pier. The remaining portions of Newport Beach to the southeast (along Balboa Peninsula) are
shown as being in a zone of localized, short-term erosion with local rates up to / on the order of
-0.5 meters per year (m/yr) or about -1.64 feet per year (ft/yr). The site itself is approximately
0.4± kilometers (1,300 feet to 1,400 feet) northwest of the Newport Harbor inlet where short-
term rates of shoreline erosion are estimated at approximately 0.26 m/yr or 0.85 ft/yr – relatively
low rates compared to the -2 m/yr (-6.5± ft/yr) reported for West Newport Beach. Using the
short-term rate of 0.85 ft/yr, shoreline erosion over the next 75 years could reduce the width of
the modern beach by as much as 64 feet. Using the higher rates reported for nearby stretches
of coast to the northwest (1.64 ft/yr), hypothetical shoreline erosion / retreat would total 123 feet
over the next 75 years. However, these are likely conservative estimates, as the long-term rates
could be significantly less and/or subject to natural fluctuations based on future sediment load,
beach nourishment, storm activity, and wave climate. Being that the shoreline fronting the
property has been relatively stable over its history, these short-term rates are likely not
representative of ongoing erosion, but more likely representative of seasonal migration of sand
from the swash zone into the nearshore / surf zone and formation of nearshore bars. As
described in the following section, seasonal shoreline change may vary by as much as 20-50
feet or more from year to year or season to season and is generally considered cyclical in
nature.
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Figure 21. Excerpt from Reference No. 9 showing long-term (purple line) and short-term (green line)
shoreline change for the northern San Pedro Cell / Huntington Beach Sub-Cell. Note the location of the
location of the site is approximately 0.4± kilometers north of Newport Harbor inlet. The short-term erosion
rate is estimate 0.26 m/yr or 0.85 ft/yr. Long-term erosion rates are not shown.
Review and Analysis of Historic Aerial Imagery
Review and analysis of historic aerial imagery available on Google Earth provides a series of
“snapshots” showing local backshore, berm, swash zone, and nearshore conditions dating back
to June 4, 2002. As a quasi-random sampling, these snapshots provide a relatively robust
dataset for evaluating the effects of acute, seasonal, and long-term erosion / shoreline change
along portions of the beach fronting the subject property. In evaluating historic aerial imagery
dating back to June 4, 2002 (Table 1, attached), we noted the date of the imagery (indicating
the season), inferred tides / winds / wave conditions (indicating wave climate and potential run
up / erosion), width of the backshore (indicating potential shoreline expansion / retreat due to
erosion), shoreline configuration (also indicative of wave climate / erosion), and other factors
having to do with apparent erosion / shoreline retreat and accretion / shoreline expansion.
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Based on our review and analysis of recent / historic aerial imagery available on Google Earth,
we note the following:
The site / subject beachfront is located approximately 1,300-1,400± feet northwesterly of
the Wedge / Newport Harbor Jetty.
Areas within the Wedge and adjacent to the Jetty appear to be prone to localized
erosion / wave attack, likely due to wave energy being focused at the intersection of the
shoreline with the Jetty.
The site itself and portions of the beach directly fronting the site straddle the transition
between the more linear / stable portions of the shoreline to the northwest, and more
variable / unstable portions of the shoreline associated with the Wedge to the southeast.
A range of tidal fluctuations were noted ranging from low to very low tides (based on
apparent widening of the swash zone and daylighted groundwater), high to very high
tides (apparent from submersion of the swash zone and encroachment onto the
backshore), and those of intermediate low and high tides.
Wind conditions were variable based on the apparent “choppiness” of the water and
orientation of small amplitude / high frequency waves, relative to the higher amplitude /
lower frequency swells.
Ocean swells and wave activity generally ranged from calm to moderate and
occasionally highly energetic with heavy shore breaks / whitewater and moderate to
strong rip currents.
Shoreline configuration also varied in concert with wave activity, ranging from relatively
straight / smooth during calm conditions, slightly irregular to moderately sinuous, to
highly sinuous / cuspate.
In general, winter storm activity tended to promote shoreline irregularity, erosion, and the
formation highly sinuous / cuspate beaches with apparently strong rip currents.
Shoreline erosion was significantly more pronounced near the Wedge, while the beach
fronting the site tended to grow and recede in a much less dramatic fashion – generally
remaining stable along with adjoining areas to the northwest throughout the years
observed.
The width of the backshore generally ranged between 300 and 400 feet throughout the
period of observation, indicating notable variability caused by short-term and apparent
long-term cycles of accretion and erosion.
A current cycle of erosion appears to have persisted since about May 2019, with the
local beach / backshore remaining relatively narrow.
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Backshore widths since May 2019 have ranged from as narrow as approximately 290±
feet and commonly between 300± feet and 325± feet – indicating a recent erosional
trend.
The backshore was apparently wider between June 2002 and June 2018 – ranging
between 330± and 400± feet in width.
The recent erosional trend may be a delayed response to recent drought-related
reductions in sediment loading from local rivers and streams and/or a lack of recent
beach nourishment activities.
Wave run up from high surf and/or high tide is also visually apparent in several photos,
indicating that wave run up may occasionally extend to within 230-270± feet of the site
during exceptional weather with high tides and storm wave activity (e.g., December 3,
2017 and October 18, 2016, respectively).
Based on the above, the site appears to be fronted by relatively wide and stable beach (i.e.,
backshore) that typically ranges in width between 300 and 400 feet. Shoreline change is cyclical
in nature and can vary by as much as 20-50 feet or more from season to season or year to year.
The beach / backshore is currently approximately 300± feet wide and is only occasionally
overtopped during exceptional high tides and storm related wave activity. The beach has
remained relatively narrow since about May 2019 but appears relatively stable under current
conditions. The width of the beach fronting the property provides a considerable buffer between
the site and swash zone – a favorable condition that limits / prevents coastal erosion and wave
attack from affecting the property. Considering the estimated short-term rate of local shoreline
erosion (0.85 ft/yr), the width of the backshore berm could hypothetically recede by as much 64
feet over the next 75 years, which would reduce its width to as narrow as 236± feet. A higher
rate of shoreline erosion (1.64 ft/yr), this would hypothetically reduce the width of the backshore
to as narrow as 177 feet. Nonetheless, we consider the observed changes in shoreline width
upon which these estimates are based to be cyclical in nature and not representative of long-
term shoreline changes. The beach fronting the site is considered to be relatively stable, as
evidenced by its performance over the past century.
Wave Run-Up / Overtopping
Air Photo Analysis and Wave Run-Up Calculations
Wave run up is the height above still water elevation that a breaking wave will run up onto the
beach. Overtopping occurs when incident wave heights and/or run up exceed the elevation of
coastal structures. With regards to the site, the current beach profile is such that the majority of
waves and their associated run ups are confined to within the swash zone, approximately
300± feet from the site. Based on estimates of horizontal wave run up overtopping the berm and
spilling over onto the backshore beach (derived from our above analysis of historic aerial
imagery), it appears that high tide storm waves may run up to within 230-270± feet of the site.
During such conditions, it is likely that storm wave run up would move sand upward and onto
the backshore. The elevation of the backshore is estimated to be between 15 and 18 feet above
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NAVD 88. Utilizing the currently estimated beach profile (see Nearshore / Inshore Bathymetry
and Beach Profile section, above) and methods of wave run up analysis provided in the Shore
Protection Manual of 1984 (Reference No. 20), assuming a 13.7 feet deep-water wave height,
15.5 second wave period (the highest observed local wave height recorded in March 1983 in
approximately 40 feet of water according to Reference No. 15), highest observed tide (+7.72
feet), breaking wave height of 21.92 feet, and breaking depth of 22’, we estimate a wave run up
elevation of approximately +16.2 feet (NAVD 88). This estimated run up elevation matches well
with the horizontal limits / inferred elevations of wave run up observed in Google Earth imagery
dated December 3, 2017, during which extreme astronomical tides of +6.95 feet and -1.48 feet
were observed at the Los Angeles Tide Station No. 9410660. Being that the site and much of
the backshore beach is above this elevation, this implies that the limits of wave run up observed
in our analysis of aerial photographs (230± feet away from the site when backshore was 345±
feet wide) represents approximately 85± feet of wave overtopping and horizontal run up / wave
incursion. A comparative analysis of wave transmission by overtopping which treats the berm as
a sub-aerially exposed breakwater with 7.28 feet of freeboard, wave run up height of 17.26 feet,
and crest width ranging from near zero to 48 feet wide, indicates a significant overtopping wave
height of about 6.5 feet, decreasing to about 2 feet over a distance 45 feet. This would suggest
a rate of reduction of wave bore height of 0.09 ft/ft and imply that an overtopping wave of
6.5 feet would dissipate over a distance of approximately 72 feet – similar to / slightly less than
the observed horizontal limits of run up estimated using Google Earth imagery (85± feet)
Given the above, the site is fronted by a relatively wide beach, favorably elevated at
El. 18± feet, and considered reasonably safe under current conditions from direct wave run up
and overtopping as a result of a wave similar to that observed during the 1982/1983 El Niño
event.
Wave Run Up, Sea Level Rise, and Overtopping
Using the “likely range” of sea level rise projections (2-3 feet by 2096) recommended in the
State Sea Level Rise Guidance document (Reference No. 4), the hypothetical elevation of wave
run up for the scenario described above would increase to about El. +18 to +19 feet. However,
the elevation of the berm would also be expected to rise with sea level and run up heights would
still be limited by energy losses across the backshore. Using the hypothetical width of the
backshore beach / berm 75 years from now (236± to 177± feet based on a erosion rates of
-0.85 to -1.64 ft/yr over the next 75 years) and the estimated distance over which run up would
be dissipated (85± feet), wave run up could hypothetically come to within 92± feet to 126± feet
of the site with future sea level rise of 2-3 feet, exceptional high tides, and high swell / storm
wave activity. Based on these estimates, the site / proposed development are considered
reasonably safe from current and future wave run up and overtopping over the next 75 years,
resulting from 2-3 feet of sea level rise.
Beyond the “likely range” of sea level rise projections, the 0.5-percent chance sea level rise
scenario (+6.1 feet in 75 years; herein, the “less than likely” scenario) would imply that storm
run up could reach elevations on the order of 20-22 feet above NAVD 88. However, as with the
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“likely range” scenario, run up heights would still be limited by energy losses across the
backshore. In other words, assuming a similar wave climate to today, the beach is a mobile
deposit that would maintain equilibrium through adjustments in elevation. This means that the
height of the berm could increase from 15± feet to possibly as high as 18± feet or more, altering
the dissipation of incident wave energy beyond the crest. Being that sea level rise of 6.1 feet
over the next 75 years is less than likely and the future configuration of the shoreline /
foreshore, berm, and backshore is difficult to predict, we defer our analysis of this hypothetical,
“1-in-200 chance” scenario to the following discussion of Coastal Flooding Hazards.
Coastal Flooding Hazards
General Overview
Coastal flooding can result from a number of factors. In the vicinity of the site and Balboa
Peninsula as a whole, the potential for coastal flooding is controlled by astronomical tides,
heavy rainfall / precipitation, storm surge, and locally as a result of wave run up / overtopping.
Under current conditions, coastal flooding is most likely to occur during periods of heavy rainfall
and astronomical high tides, which can diminish the capacity of and overwhelm existing storm
drain infrastructure that ultimately drains to the ocean. According to Reference No. 15:
Most storms occur during the winter months;
Monthly extreme tides tend to show higher peaks during the winter and summer;
Monthly mean sea levels fluctuate seasonally, with higher values during the fall and
lower values during the spring;
El Niño events (when sea surface temperatures are higher than normal) also tend to
coincide with periods of higher rainfall / storm activity and higher sea levels (0.3-0.6 feet
higher than average), and occur about every 3- to 7-years on average; and
Short-term storm effects due to wind speeds and ocean surface atmospheric pressure
anomalies can locally increase water levels by as much as 3 feet, but average
departures from astronomical tides are believed to be more on the order of 1 foot or less.
Given the lowest existing site elevation on the north side of the property (which is as much as
6 feet higher than the low-lying areas on the north- / harbor-side of the peninsula) and presence
of the elevated berm / backshore beach fronting the south side of the property, coastal flooding
is most likely to occur (under current conditions) north and west of the property in low-lying /
flood-prone areas. With respect to the alleyway fronting the north side of the property,
temporary flooding may be possible as a result of acute heavy rainfall but would likely be
temporary / short-lived under current conditions. However, when accounting for future sea level
rise, the potential for and magnitude of flooding may increase over the project’s design life. A
review and evaluation of available information regarding coastal flooding hazards is provided
below with reference to sea level rise projections, 100-year / El Niño storm events, and related
scenarios regarding potential future mitigation pathways
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Flood Insurance Rate Maps (FIRM)
According to the FIRM mapping prepared by the U.S. Department of Homeland Security –
Federal Emergency Management Agency (FEMA; Reference No. 10; see Figure 22, below), the
site is located in an area reportedly with a 0.2-percent annual chance flood hazard (1-in-500
chance / occurring once every 500 years on average / 500-year recurrence interval) or
1-percent annual chance flood hazard (i.e.., 100-year recurrence interval) with average depths
less than 1 foot or with drainage areas less than 1 square mile. The site is not identified as
being in a Special Flood Hazard Area or Other Areas of Flood Hazard, including 100-year flood
hazards under current and future conditions. We note that the nearest Special Flood Hazard
Area is located approximately 175± feet southwest of the site, with a flood elevation of 18 feet.
The flood elevation and distance of the Special Flood Hazard Area corresponds to a 100-year
event and appears to be consistent with the anticipated limits of wave run up encroaching on
the existing and future anticipated backshore berm / beach.
Figure 22. Flood Insurance Rate Map (FIRM) showing site’s location in a 0.2 percent Annual Chance
Flood Hazard area or area with 1 percent chance flood with average depth of less than one foot or with
drainage area of less than one square mile.
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CoSMoS / Our Coast Our Future Hazard Mapping
A review of the Our Coast Our Future Hazard Map for Newport Beach (Reference No. 6)
provides illustrative GIS mapping of future shoreline configurations based on a range of sea
level rise projections and storm scenarios. The Hazard Map uses data from the Coastal Storm
Modelling System (CoSMoS) for southern California (Reference No. 5) to model the local effects
of sea level rise and annual, 20-year, and 100-year storms. A scenario report is included in
Appendix B, showing the percent flooded area of the site under different scenarios of sea level
rise and flooding. Based on our review of the scenario report and flood hazard maps, we note
the following:
Under current conditions, the site is shown as being above the limits of 100-year
flooding. However, low-lying / flood prone areas are shown to exist north of the site
fronting Newport Harbor and along westernmost Balboa Avenue.
With approximately 3 feet of sea level rise or approximately 100 centimeters (cm), the
site is still above the flood zone. However, the width of the backshore beach is reduced
and limits of wave run up are shown coming to within 220± feet of the site during
100-year storm conditions. Also, Balboa Avenue is shown as being completely
inundated, along with low-lying flood prone areas adjoining the harbor to the north.
Ocean Boulevard is also shown as being flooded.
With 6.1 feet of sea level rise or approximately 200 cm, the alleyway fronting the north
side of the property is shown as being flooded, implying that the entrance to the garage
and proposed basement level could be inundated under such a scenario. Risk of
flooding increases with 100-year storm activity. However, the rear patio and backshore
beach appear to remain above the 100-year flood level, with the limits of wave run up
coming to within approximately 150± feet of the property.
Overall, the scenario report included in Appendix B indicates that the site itself is
reasonably safe from 100-year storms combined with sea level rise up to approximately
150 cm (4.92 feet). With 175 cm (5.74 feet) of sea level rise, the site becomes
susceptible to being partially inundated under 20- and 100-year storm conditions. At
200 cm (6.56 feet) of sea level rise, the site is indicated as being partially flooded under
annual storm events.
Based on the above, the site is shown as being reasonably safe from sea level rise up to about
4.92 feet (150 cm) with or without 100-year storm events over the next 75 years. The width of
the backshore beach would be reduced to approximately 230± feet (during mean high water)
and subject to wave heights on the order of 3-4 m (9.8-13.1 feet), with wave run up / incursion to
within approximately 220± feet of the site under 100-year storm conditions. Offsite, even with
only 3 feet of sea level rise, much of western Newport Beach and northern Balboa Peninsula
becomes flood prone / inundated.
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UC Irvine / FloodRISE Hazard Mapping
The University of California Irvine for Flood Resilient Infrastructure & Sustainable Environments
(FloodRISE) is funded by the National Science Foundation (NSF) to research the potential for
metric resolution flood hazard simulations to enhance flood risk management. A major focus of
FloodRISE includes the GIS-based Flood Hazards map for Newport Bay, which provides
relatively precise mapping of probabilistic flood hazards affecting Newport Bay, Balboa
Peninsula, and other surrounding areas, projected up through the years of 2015, 2035, and
2050. Overall, the results provided by FloodRISE are similar to and consistent with those
provided by Our Coast Our Future / CoSMoS, indicating that the site is reasonably safe from
flooding under a combination of conditions projected through 2050. Road blockage by flooding /
inundation of low-lying areas including those along Balboa Boulevard appears to be the most
significant hazard offsite. Based on the road blockage mapping for 2050, it is anticipated that
there could be a 20-40 percent annual probability or greater of flooding / road blockage
impacting low-lying areas along Balboa Boulevard, potentially blocking access to and from the
site under such conditions.
Tsunami
General Overview
Tsunamis are very long-period / low frequency waves that are generated in the open ocean by
large displacements of water, primarily by tectonic faulting / earthquake-related movements
and/or submarine landslides. They can travel thousands of miles across the Pacific Ocean, but
they’re felt effects (e.g., wave heights, run up, currents, flooding / inundation, damage to man-
made structures, etc.) vary significantly depending on: distance and direction from the source;
the presence of islands / break waters; changes in wave heights caused by local offshore and
nearshore bathymetry; and onshore topography, controlling horizontal limits of wave incursion /
run up / flooding. Metorite impacts can also produce tsunamis, but such events are considered
relatively rare with respect to known occurrences in the geologic record. In the Pacific Ocean,
tectonic / geologically active tsunamigenic sources are present along the coasts of Oregon,
Washington, Alaska, Japan, and South America, primarily in association with subduction zones
along the edges of the Pacific Plate (i.e., “Ring of Fire”). Historic and pre-historic tsunamis from
these sources has caused significant damage, but primarily along the northern California coast.
Southern California and Newport Beach are generally at a lower risk from subduction-related
sources due to being more distant (waves attenuate over longer distances), having favorable
shoreline orientation and local bathymetry (generally oblique to or facing / sloping away from the
source), and shielding by the Channel Islands and peninsulas / promontories along the coast
(acting as local break waters).
Low-lying beaches, harbors, and estuaries are at the greatest risk of being impacted by local
and regional tsunamis. For example, the 2011 Tohoku earthquake and tsunami that struck
Japan also impacted 27 harbors along the California coast, which sustained a total of
$100-million in damages (Reference No. 21). In Newport Harbor, no damage was reported, but
a maximum measured wave amplitude of about 0.3 meters (~1 foot) and induced currents up to
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5 knots were reported (Reference No. 22). Local tsunami wave heights up to 0.4 meters (1.3
feet) have been estimated based the USGS’s SAFRR Tsunami Scenario (Reference No. 23;
Figure 23, below), which is based on simulations of a moment magnitude (Mw) 9.1 earthquake
offshore of the Alaska Peninsula, similar to that of the 1964 Alaska Earthquake. Historic and
future anticipated tsunamis of this nature have been and will be of little consequence with
respect to the site itself. However, local sources (submarine landslides and regional fault lines)
are hypothesized to exist in the offshore areas of southern California’s Continental Borderland,
but the potential for and magnitude of local tsunamis is a topic of ongoing research and
scientific study.
Figure 23. Excerpted map from Reference No. 23 of USGS Science Application for Risk Reduction
(SAFRR) project simulation showing limits of tsunami inundation (red) based on Mw 9.1 earthquake off of
the Alaska Peninsula. Approximate location of project site is shown with black circle and is shown as not
being with the tsunami inundation zone.
Local Site Assessment
Topographic and regional maps indicate the subject site is approximately 400± feet inland of the
Pacific Ocean and 1,000± feet westerly of Newport Harbor. The site sits at an estimated
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elevation of 13-18± feet above NAVD 88 and the Tsunami Hazard Map for Orange County
(Reference No. 24) indicates that the site is within an area identified as having the potential for
tsunami inundation for an event having a 975-year average return period. Based on the above,
there is potential risk of inundation due to a tsunami event from known sources in the Pacific
Ocean. Additionally, ongoing research by Legg et al. (2003; Reference No. 24) and others
suggests that tsunami wave run up values of 1-2 meters (3-7 feet) and possibly as high as
2-4 meters (7-13 feet) may be possible, which could arrive in as little 10-20 minutes – however,
tsunamis of this size are not known to have occurred historically and would likely be
exceptionally rare in recurrence compared to more active, subduction-related sources along the
Pacific Rim. Nonetheless, hypothetical wave / run up heights indicated in Reference No. 24,
occurring during high tide, would reach elevations of 10-15 feet above NAVD 88 and possibly as
high as 20-21 feet – values considered very conservative / deterministic in nature and yet to be
proven in terms of probabilistic significance. Nonetheless, the lower levels of the site / proposed
residence could hypothetically be impacted under such a scenario, but the chances of such an
event occurring would likely be very low based on currently available information. Regardless,
the site is located and elevated favorably compared to other areas along Balboa Peninsula and
is considered reasonably safe from being directly impacted by lower-bound / historically similar
tsunami hazards over the project’s design life of 75 years.
Tsunami Emergency Information
The City of Newport Beach offers Tsunami Emergency Information (Reference No. 25).
Earthquakes and rapid changes in water level (i.e., receding waters) are primary indicators of
potential tsunami. Official warnings from emergency responders, warning sirens, and/or
emergency announcements may also be provided in the event of potential tsunami.
Reference 25 offers additional information regarding when evacuation higher ground and/or
sheltering in place should be considered. In the event of a tsunami, Balboa Avenue would be
the primary evacuation route, but may be overwhelmed by heavy traffic. Depending on the wave
heights and estimated travel times / time of arrival, evacuation to higher ground and/or
sheltering in place would be recommended. The proposed residence is planned to have a
second story at El. 26-28± feet and roof deck at El. 26-37± feet, respectively, providing potential
options for sheltering in place – however, per Reference No. 25, this should only be considered
as a “last resort” in the event of a tsunami being generated in the local offshore region with little
warning and/or time to evacuate.
Seiche
Seiche is defined as a standing wave oscillation effect generated in a closed or semi-closed
body of water caused by wind, tidal current, and/or earthquake. Seiche potential is highest in
large, deep, steep-sided reservoirs or water bodies. The site is not near any significant pools,
lakes, reservoirs, or similar, is 1,000± feet from Newport Harbor and 400± feet inland of the
Pacific Ocean. Given that, the potential risk of seiche-related effects impacting the proposed
residence from existing water bodies is considered very low to nil.
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GEOLOGIC STABILITY
As described in our Preliminary Geotechnical Investigation / Engineering Geologic Evaluation
Report for the project, the major geotechnical factors affecting the geologic stability of the site
and proposed development include:
1. Presence of relatively loose sands occurring in the shallow subsurface and saturated
sands / groundwater at general depths of 4-13± feet below ground surface – site
dewatering would be required for a conventional remedial grading scheme. However, the
remedial grading efforts currently planned will include the use of secant piles and deep
soil mixing (soilcrete). Based on previous discussions with design-build ground
improvement contractors for the soilcrete, dewatering will not be required.
2. Potential soil disturbance resulting from the demolition of the existing residence and
ancillary elements.
3. Static settlement due to foundation / improvement loading and dynamic settlement
resulting from earthquake-induced liquefaction and shallow dry sand settlement.
4. Below-grade excavations required to facilitate subterranean level construction proximal
to adjacent property lines and below existing groundwater levels – requiring appropriate
shoring, waterproofing, and ground stabilization during and following construction.
5. High ground accelerations / seismic shaking may be experienced at the site as a result
of local and/or regional earthquakes during its design life – therefore, the proposed
structures should be designed and constructed to the prevailing standards and seismic
design requirements.
6. The potential presence of buried rip rap within the proposed secant pile / soilcrete prism,
requiring post-demolition exploration and screening to verify clearance.
7. Corrosion potential due to the local environment / coastal setting.
8. Engineering geologic considerations including the potential for shallow groundwater,
coastal flooding, and other hydrogeologic hazards.
9. Soil exposure issues related to control of external influences on the structure – including
water / moisture / vapor, vegetation (landscaping), soil chemistry (i.e. sulfate / pH /
corrosivity issues), exposure to rain, weather, and coastal environment.
In consideration of the above and as described in Reference No. 1, the ground underneath the
site is to be improved by means of secant pile installation and deep soil mixing (i.e., soilcrete) to
depths on the order 23-28 feet below ground surface. The planned secant pile / soilcrete prism
will effectively eliminate the potential for meaningful soil liquefaction, adverse ground settlement,
and groundwater intrusion during and following construction. During construction, the secant
piles are planned to accommodate basement level construction and provide both temporary and
permanent shoring and support along property lines. Following construction, the site will still be
prone to experiencing potentially high ground accelerations over its design life due to local and
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regional earthquakes, but the geologic stability of the supporting ground will be increased
significantly utilizing the recommended secant pile / soilcrete system. The remaining
considerations listed above have been addressed in Reference No. 1 and will be mitigated as
part of the overall design and final construction. Regardless, the site is considered geologically
stable and the proposed development is considered feasible from an engineering geologic
standpoint, provided that the recommendations in our Reference No. 1 report are incorporated
into the final design and as-built construction.
CONCLUSIONS
California Coastal Commission Sea Level Rise Guidance Information
Step 1
Establish the projected sea level rise range for the proposed project’s planning horizon (life of
project) using the current best available science:
Using the latest State of California Sea Level Rise Guidance Document (2018;
Reference No. 4), the “likely range” of sea level rise projections for the year 2096 (“low risk
aversion” scenario for project design life of 75 years) are estimated at 2-3 feet, with a reported
66 percent probability of occurrence. A “high risk aversion” scenario with a 0.5 percent
probability (1-in-200 chance of occurrence) suggests that sea level can rise as high 6.1 feet by
2096. However, this latter scenario is considered herein as “less than likely” and a hypothetical
worst case. It is also noted herein that if sea level rise continues at rates consistent with
approximately the last century, then sea level rise of about 0.2-0.5 feet may be expected.
Result: Acceptable
Step 2
For each sea level rise scenario identified in Step 1, determine how physical impacts from sea
level rise may impact the project site, including erosion, structural and geological stability,
flooding and inundation.
Wave Uprush and Wave Impacts: Based on the “likely range” of sea level rise projections
provided in the State’s Sea Level Rise Guidance document (Reference No. 4), there are no
material impacts to the site itself when considering sea level rise of 2-3 feet, shoreline erosion /
retreat of 64-123 feet, wave run up / overtopping involving 1982/1983 El Niño-type storm wave
heights of 13.7 feet and periods of 15.5 seconds, and highest observed tides of +7.72 feet or El.
9.7-10.7 feet above NAVD 88. This finding also holds for a hypothetical sea level rise of 6.1 feet,
as the backshore beach / berm is a mobile deposit that would provide sufficient buffer.
Nonetheless, the site itself and proposed new residence is considered reasonably safe from
being directly impacted by coastal hazards identified herein over the next 75 years.
Result: Acceptable
Geologic Stability: Geologic stability of the site / proposed development has been evaluated
under separate cover (Reference No. 1). As discussed in Reference No. 1, the major factors
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Newport Beach, California
affecting the geologic stability of the site / proposed development involve the presence of
shallow groundwater and liquefiable soils present under the site / existing residence. In order to
mitigate soil liquefaction and shallow groundwater intrusion, a secant pile / deep soil mixing
program utilizing soil cement (“soilcrete”) has been proposed in addition to appropriate
waterproofing and geotechnical design of the proposed basement level. It is noted herein that
sea level rise will cause groundwater elevations to increase proportionally, but this will not
impact site / proposed residence, as the basement will waterproofed and designed to resist
hydrostatic forces. The secant pile / deep soil mixing / soilcrete prism will be established to
depths on the order of 23-28 feet below existing ground surface, thereby mitigating liquefaction /
seismic settlement hazards and providing an added layer of protection against shallow
groundwater intrusion. As such, the site / proposed development will be considered reasonably
safe and geologically stable over the project’s 75-year design life. Nonetheless, as discussed in
Reference No. 1, the site is in a seismically active region of southern California and will be
subject to ground shaking which can be mitigated through appropriate seismic design and
construction.
Result: Acceptable
Erosion: Based on our review and evaluation of historic estimated rates of shoreline change,
the site is considered reasonably safe from being impacted directly by shoreline erosion over its
design life of 75 years. The site is fronted by a relatively stable berm and backshore beach that
ranges in width between approximately 300 and 400 feet. Conservatively applying short-term
estimated rates of shoreline erosion between 0.85 ft/yr and 1.64 ft/yr over the next 75 years
indicates that the backshore beach would still provide a significant buffer of 177-236 feet in
width – consistent with the findings based on our review and analysis of the Our Coast Our
Future and Flood RISE hazard mapping.
Result: Acceptable
Flooding and Inundation: The results of our coastal hazards evaluation indicate that the
physical impacts of sea level rise on the site / proposed development are limited to partial
inundation – only under the “less than likely” / “high risk aversion” scenario and/or with sea level
rise exceeding approximately 4.92 feet (Appendix B). The probability of sea level rise exceeding
4.92 feet is reportedly less than 5 percent / 1-in-20 chance. Partial inundation impacts (with
greater than 4.92 feet and/or 6.1 feet of sea level rise) mainly would affect the garage / driveway
(El. 13± feet) and proposed basement level (El. +7.35 feet) that front the alleyway on the north
side of the property. The proposed first floor level (El. 16.37 feet) will be approximately 2.55 feet
above the elevation of the “less than likely” sea level plus highest observed tide level (El. 13.82
feet). Offsite, the greatest impacts involve a 20-40 percent or greater chance of partial flooding /
inundation of Balboa Peninsula and road related road blockage along Balboa Avenue by 2050.
Result: Acceptable
Other Impacts: There are no other impacts of consequence to the project having to do with sea
level rise. Saltwater intrusion due to a shallower groundwater table is mitigated by the planned
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Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront Page 39 of 42
Newport Beach, California
secant pile / deep soil mixing / soilcrete system, along with basement level waterproofing, mat
slab, and retaining wall foundations.
Result: Acceptable
Step 3
Determine how the project may impact coastal resources, considering the influence of sea level
rise over the life of the project. Resources to consider shall include public access and
recreation, coastal habitats, water quality, archaeological/paleontological resources and scenic
resources.
The project has no material impacts on coastal resources over the life of the project, even when
factoring sea level rise. The proposed new residence will not have any material impacts on
public access / recreation, coastal habitats, or water quality. The site is underlain by historic,
quasi-natural / man-made fills and the local area Balboa Peninsula itself is not known to contain
any archaeological or paleontological resources of significance. In terms of scenic resources,
the proposed development is not anticipated to impact scenic resources, provided that
appropriate planning and design of the proposed residence structure follows appropriate
jurisdictional guidelines and requirements in accordance with the approved Coastal
Development Permit.
Result: Acceptable
Step 4
Seek alternatives to avoid resource impacts and minimize risk to the project, such as increasing
heights of sea walls or finished floor elevations.
The proposed development does not impact coastal resources and the finished first floor
elevations well above the highest anticipated and hypothetical flood elevations when accounting
for sea level rise. The basement level may be impacted by nuisance water as result of heavy
rainfall / storm activity affecting the adjoining alleyway to the north. Watertight garage doors,
appropriate exterior and interior surface drainage, and an emergency sump-and-pump system
for collecting and discharging surface water that may enter the basement, for whatever reason,
may be considered for mitigation / added benefit. Considerations for corrosivity and salt spray
should also be incorporated into the final design / construction, as appropriate. Also, as with all
basements, some degree of dampness, moisture, and/or vapor should be anticipated, but can
be mitigated with appropriate ventilation, waterproofing, drainage, etc.
Result: Acceptable
Step 5
In conjunction with the approval of the CDP, appropriate conditions of approval will be placed on
the project.
Result: Acknowledged
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Newport Beach, California
STATEMENT OF QUALIFICATIONS
Erik C. Haaker, PG 9409, CEG 2708 – Senior Engineering Geologist
Mr. Haaker is a highly skilled and experienced geoscientist / professional engineering geologist
with extensive background in geotechnical engineering, coastal geomorphology, neotectonics /
earthquake geology, seismic hazards assessment, and Quaternary geology / paleo-sea level
history of the southern California coastal region. As a senior engineering geologist at
G3SoilWorks, Inc., he has been with the company for nearly 12 years and carries licensure from
the State of California as both a practicing Professional Geologist and duly Certified Engineering
Geologist. He holds Bachelor’s (2012) and Master’s (2014) of science degrees in geology /
engineering and geological sciences from San Diego State University. As both an
undergraduate and graduate student in the Department of Geological Sciences, he studied
under and worked closely with Dr. Tom Rockwell, participating in numerous academic and
professional research studies focused on: seismic hazards associated with the Newport
Inglewood / Rose Canyon, Elsinore, San Jacinto, Ventura, and San Andreas fault zones;
structural geology, geomorphology, and tectonic evolution of the southern California coastal
region; and Quaternary sea level history / paleoclimatology. To that end, he has authored and
coauthored several papers / research studies focused on the tectonic geomorphology and
seismic hazards that characterize the coastal zones of San Diego, southern Orange County,
and Ventura. During his tenure as a graduate student, he worked for Dr. Rockwell and southern
California Edison on the seismic hazards assessments that focused on the San Onofre Nuclear
Generating Station (SONGS) – his research involved detailed mapping and high resolution
dGPS surveys of Pleistocene marine terraces spanning the coastal zone from San Diego to
Newport Beach and evaluation / re-assessment of seismic hazards associated with the Newport
Inglewood / Rose Canyon fault zone and Continental Borderland. The findings of his research
were published in the Association of Environmental and Engineering Geologists’ Special
Publication 26 – Applied Geology in California. Mr. Haaker has worked on several high-profile,
local coastal development projects, including the Aerie Project, 239 Carnation, 401 Avocado,
and 2495 Ocean Boulevard. He is a groundwater expert and has direct local experience in
evaluating coastal, seismic, geologic, and hydrogeologic hazards affecting the site, proposed
development, and Balboa Peninsula as a whole.
Larry E. Fanning, PG 6118, CEG 1907 – President / Principal Scientist
Mr. Fanning is a highly skilled and experienced geoscientist with significant background in
coastal processes. He is President and Principal Geoscientist at G3SoilWorks, Inc, and has
held that position for over 12 years, and has over 38 total years experience in geosciences,
engineering geology, and geotechnical engineering – and is both a Professional Geologist and
duly Certified Engineering Geologist, as well as a certified research diver. He holds degrees in
Geology and Geophysics from UC Santa Cruz (1985), where he studied coastal processes,
oceanography, quaternary processes, and environmental/developmental geology under and
worked for Dr. Gary Griggs and other professors. His work with Dr. Griggs included
documenting and studying damages along the central California (Monterey, Santa Cruz,
Pacifica, San Francisco, coast in the major storm events of 1980 and 1982 (including the
Pineapple Express), littoral drift and harbor interactions, as well as wave attack and coastal bluff
350 Fischer Ave. Front Costa Mesa, CA 92626 P: 714 668 5600 www.G3SoilWorks.com
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Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront Page 41 of 42
Newport Beach, California
retreat behavior. Mr. Fanning has played key roles in numerous coastal projects in Palos
Verdes, Newport Coast, Monarch Beach / St. Regis, Huntington Beach, Malibu, and Hope
Ranch. Mr. Fanning is also working with the Mexican Government and the State on the
comprehensive design and implementation of a major water transfer project mining coastal sea
groundwater for use in restoring the Salton Sea and desalination efforts, and disposing of brine
through offshore specialized pipelines in the Northern Gulf of California. Notably, Mr. Fanning
has also served as a Subject Matter Expert to the California Board of Registration, and as a full
Board Member to the State Department of Conservation – State Mining and Geology Board.
With regards to familiarity with the local area, Mr. Fanning has worked on numerous projects in
the Newport area, including the Aerie Project, Newport Shipyard, and Sea Forever. He was
also trained by the USCGA in seamanship and has done extensive boating in the capacity of
Captain, and has significant familiarity with the local coastline.
Daniel J. Morikawa, PE 49,453 GE 2726 – Director of Engineering
Mr. Morikawa has extensive and varied experience in the field in the Geotechnical Engineering
and Engineering Geology in the southern California area over the past 45 years. His past
educational background and degree in Engineering Geology was obtained from UCLA and he is
currently a California Registered Civil and Geotechnical Engineer. He has been involved with
numerous coastal projects in concert with the signing Engineering Geologists relevant to coastal
hazard evaluations in the Ventura, Los Angeles, and Orange County areas, with review and
approval by the California Coastal Commission. Recent projects involving coastal hazard
assessments include single-family residential construction, condominium / apartment
development, and replacement seawall construction in the Newport Beach and Ventura areas.
LIMITATIONS
This report has been prepared for the exclusive use of Mr. Scott Schwartz, his design
consultants, the City of Newport Beach, and California Coastal Commission to facilitate review
and approval of a Coastal Development Permit for the proposed new residence construction.
This report is not intended for other parties, and it may not contain sufficient information for
other purposes. The Owner or their representative should make sure that the information and
preliminary recommendations presented in this report are brought to the attention of the Project
Architect, Project Civil, Project Structural Engineer, Project Ground Improvement Design
Engineer and made part of the project plans. The findings and conclusions presented herein
were developed in accordance with generally accepted professional engineering principles and
local practice in the field of engineering geology and geotechnical engineering and reflect our
best professional judgment. We reserve the right to revise and/or modify our working opinions
based on new information and make no other warranty, either express or implied.
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Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront Page 1 of 2
Newport Beach, California
LIST OF SELECTED REFERENCES
1) G3SoilWorks, Inc., Preliminary Geotechnical Investigation / Engineering Geologic
Evaluation, Proposed New Residence Construction, 2050 East Oceanfront, Newport
Beach, California, Project No. 1-1201, dated December 20, 2021.
2) City of Newport Beach, Title 21 – Local Coastal Program Implementation Plan, Ordinance
2016-19, California Coastal Commission Approval: September 8, 2016, City Council
Approval: November 22, 2016, Effective Date: January 30, 2017.
3) City of Newport Beach – Community Development Department / Planning Division, Coastal
Development Permit Supplemental Materials Checklist, Revised: May 21, 2021.
4) State of California, Sea-Level Rise Guidance Document: 2018 Update.
5) Barnard, P.L., Erikson, L.H., Foxgrover, A.C., Limber, P.W., O'Neill, A.C., and Vitousek, S.,
2018, Coastal Storm Modeling System (CoSMoS) for Southern California, v3.0, Phase 2
(ver. 1g, May 2018): U.S. Geological Survey data release,
https://doi.org/10.5066/F7T151Q4.
6) Our Coast Our Future Hazard Map website accessed on October 28, 2021:
https://ourcoastourfuture.org/hazard-map/.
7) City of Newport Beach – Public Trust Lands Sea Level Rise Vulnerability Assessment,
Prepared by: Moffat & Nichol, Prepared for: City of Newport Beach, Dated: April 10, 2019.
8) University of California Irvine, FloodRISE – Newport Bay Flood Hazards GIS Mapping
website accessed on October 28, 2021:
https://ucirvine.maps.arcgis.com/apps/webappviewer/index.html?id=4570d7dbfb674aac9
887a20eea9c0c4f.
9) Hapke, C.J., Reid, D., Richmond, B.M., Ruggiero, P., and List, J., 2006, National
assessment of shoreline change: Part 3: Historical shoreline changes and associated
coastal land loss along the sandy shorelines of the California coast: U.S. Geological Survey
Open-file Report 2006-1219.
10) Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) for
2050 East Oceanfront, Newport Beach, California, Accessed on December 16, 2021,
https://msc.fema.gov/portal/search?AddressQuery=2050%20E%20Oceanfront%2C%20N
ewport%20Beach%2C%20CA#searchresultsanchor.
11) Patsch, Kiki, and Gary Griggs, Littoral Cells, Sand Budgets, and Beachs: Underanding
California’s Shoreline, Institute of Marine Sciences, University of California Santa Cruz,
California Dept. of Boating and Waterways, and California Coastal Sediment Management
WorkGroup, Brochure Dated: October 2006.
12) Apex Land Surveying, Inc., Topographic Map, 2050 East Oceanfront, Newport Beach, CA
92661, APN: 048-262-18, Scale: 1 inch = 8 feet, Date: April 30, 2021.
13) Morton, P.K. and F.K. Miller, 2006, Geologic Map of the San Bernardino and Santa Ana 30’
x 60’ quadrangles, U.S. Geological Survey Open-File Report 2006-1217, Online Version
1.0, prepared in cooperation with California Geological Survey.
350 Fischer Ave. Front Costa Mesa, CA 92626 P: 714 668 5600 www.G3SoilWorks.com
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Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront Page 2 of 2
Newport Beach, California
14) Haaker, E.C., T.K. Rockwell, G.L. Kennedy, L.G. Ludwig, S.T. Freeman, J.A. Zumbro, K.J.
Mueller, and R.L. Edwards, 2016, Style and rate of long-term uplift of the southern
California coast between San Diego and Newport Beach with Potential Implications for
Assessing Blind Thrust Models, Chapter 37 in Applied Geology in California, Association
of Environmental and Engineering Geologists Special Publication 26, Star Publishing
Company, Inc.
15) U.S. Army Corps of Engineers – Los Angeles District, Coast of California Storm and Tidal
Waves Study, South Coast Region, Orange County, Nearshore Hydrodynamic Factors and
Wave Study of the Orange County Coast, Final Report, Report No. 96-3, January 1996.
16) Simms, A.R., Rood, D.H., and T.K. Rockwell, Correcting MIS5e and 5a sea-level estimates
for tectonic uplift, an example from southern California, Quaternary Science Reviews,
Volume 248, article id. 106571, Publication Date: November 2020.
17) Lindsey, Rebecca and Luann Dahlman, Climate Change: Global Temperature, Published
March 15, 2021, Updated August 12, 2021, https://www.climate.gov/news-
features/understanding-climate/climate-change-global-temperature.
18) Dipl. Biol. Ernst-Georg Beck, Postfach 1409, D-79202 Breisach, Germany, Evidence of
variability of atmospheric CO2 concentration during the 20th century, Discussion paper,
May 2008.
19) Kopp, R. E., R. M. Horton, C. M. Little, J. X.Mitrovica, M. Oppenheimer, D. J.Rasmussen,
B. H. Strauss, and C. Tebaldi (2014), Probabilistic 21st and 22nd century sea-level
projections at a global network of tide-gauge sites, Earth’s Future, 2,
383-406,doi:10.1002/2014EF000239.
20) U.S. Army Corps of Engineers, Shore Protection Manual, Volume 2, Fourth Edition, 1984.
21) California Geological Survey et al., The March 11, 2011 Tohoku Tsunami in Japan and
California, https://www.conservation.ca.gov/cgs/Documents/Tsunami/tohoku-poster.pdf.
22) California Coastal Commission, The Tohoku Tsunami of March 11, 2011: A Preliminary
Report on Effects to the California Coast and Planning Implications, Dated: April 13, 2011,
Revised: April 18, 2011.
23) Ross, S.L., Jones, L.M., Miller, K., Porter, K.A., Wein, A., Wilson, R.I., Bahng, B.,
Barberopoulou, A., Borrero, J.C., Brosnan, D.M., Bwarie, J.T., Geist, E.L., Johnson, L.A.,
Kirby, S.H., Knight, W.R., Long, K., Lynett, P., Mortensen, C.E., Nicolsky, D.J., Perry, S.C.,
Plumlee, G.S., Real, C.R., Ryan, K., Suleimani, E., Thio, H., Titov, V.V., Whitmore, P.M.,
and Wood, N.J., 2013, The SAFRR tsunami scenario—Improving resilience for California:
U.S. Geological Survey Fact Sheet 2013–3081, 4 p., https://pubs.usgs.gov/fs/2013/3081/.
24) California Geological Survey, Tsunami Hazard Area Map, County of Orange, State of
California, County of Orange, dated July 8, 2021.
25) Legg, Mark R., Jose C. Borrero, and Costas E. Synolakis, Evaluation of Tsunami Risk to
Southern California Coastal Cities, The 2002 NEHRP Professional Fellowship Report,
Earthquake Engineering Research Institute, PF2002-11, January 2003.
26) City of Newport Beach, Tsunami Emergency Information, Accessed on December 16,
2021, https://newportbeachca.gov/home/showdocument?id=9126.
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Site Location
(2050 E Oceanfront)
The
“Wedge”
Dec. 2021
Figure 142050 East Oceanfront
Coastal Setting and Near-Shore Bathymetry
Newport Beach, CA
Project No. 1-1201
Notes: Basemap from NOAA
National Ocean Service Coast Survey 18754
Newport Bay, Scale 1:10,000, NAD 1983
dated October 5, 2021.
Soundings in feet at mean lower low water.
Inset aerial photo from Google Earth.
0ft 200 800ft
100 400N
1 inch = 800 feet
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Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021 Proposed New Residence Construction Project No. 1-1201 2050 East Oceanfront Page 1 of 4 Newport Beach, California Table. 1 – Analysis of Coastal Erosion / Wave Attack Based on Review of Historic Aerial Imagery from Google Earth Date of Image Inferred Tide / Wind / Wave Conditions Width of Backshore Shoreline Configuration Other Notes August 1, 2021 Intermediate Tide / Mild to Moderate Shore Breaks 290-360± feet Moderately Irregular / Slightly Sinuous Wave run up during high tide appears to have extended to within 260± feet of site. February 20, 2021 Low Tide / Mild Shore Breaks 315± feet Moderately to Highly Irregular / Slightly Sinuous Beach appears to be in a seasonally eroded condition localized erosion / irregularity increasing to southeast. October 30, 2020 Intermediate High Tide / High Energy Shore Breaks near Wedge 325± feet Relatively Straight Significant shore breaks and erosion near Wedge; Beach fronting site appears stable. October 28, 2020 Intermediate High Tide / Calm 325± feet Relatively Straight Shoreline is calm and slightly eroded near Wedge; Beach fronting site appears stable. March 21, 2020 Intermediate High Tide / Very Windy / Choppy with Moderate Shore Breaks 305± feet Moderately Sinuous 100± feet wide swash zone. January 22, 2020 Low Tide / Calm 300± feet Slightly Irregular / Relatively Straight with Minor / Very Low Amplitude Sinuosity Beach appears to be in a relatively stable condition with minimal erosion near the Wedge. May 2, 2019 Very Low Tide / Southwesterly Swell / Westerly Winds 290± feet Highly Sinuous / Cuspate with Steep Scarp at High Tide Line Water appears very turbid near swash zone. PA2022-0167
Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021 Proposed New Residence Construction Project No. 1-1201 2050 East Oceanfront Page 2 of 4 Newport Beach, California Date of Image Inferred Tide / Wind / Wave Conditions Width of Backshore Shoreline Configuration Other Notes June 28, 2018 Intermediate Low Tide / High Westerly Winds / Southerly Swell 350± feet Moderately Irregular / Sinuous with Localized Cusps Shoreline appears to have expanded by as much as 50-100± feet. April 2, 2018 Intermediate High Tide / Calm 345± feet Moderately Sinuous Shoreline is highly sinuous / cuspate near Wedge, straighter / apparently more stable in front of site, and expanded 50± feet. December 3, 2017 Intermediate Low Tide / Calm to Moderate Wave Activity 345± feet Relatively Straight, but Sinuous / Cuspate to Southeast near Wedge Sand appears to have been wetted by wave run up and subsequently groomed; wetted area extends to within 230± feet of site. October 18, 2016 Low Tide / Slightly Windy / Moderate Wave Activity 345± feet Relatively Straight with minor sinuosity As above, wave run up appears to have encroached within 270± feet of site; Water appears turbid near swash zone. February 2, 2016 Low Tide / Calm Winds / Moderate Southwest Swells 350± feet Relatively Straight / Smooth with Bars and Troughs apparent to northwest and Accreted Shoreline to Southeast Shoreline appears to be in expanded condition; Sand appears to have been wetted, possibly by rainfall. March 24, 2015 Intermediate Tide / Moderate Wind and Wave Activity 350± feet Moderately Straight with Localized Sinuosity / Irregularity Relatively Calm Conditions PA2022-0167
Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021 Proposed New Residence Construction Project No. 1-1201 2050 East Oceanfront Page 3 of 4 Newport Beach, California Date of Image Inferred Tide / Wind / Wave Conditions Width of Backshore Shoreline Configuration Other Notes April 23, 2014 Intermediate High Tide / Windy / Choppy and High Surf / Southwesterly Swells 400± feet Highly Sinuous / Cuspate / High Energy Broad Zone of whitewater fronting shoreline July 17, 2013 Intermediate High Tide / Windy / Choppy and Moderate South-Southwesterly Swells and Wave Activity 350-400± feet Relatively Straight to Slightly Irregular Shore Breaks and Erosion near Wedge April 16, 2013 High Tide / Windy / Choppy with High-Energy, South-Southwesterly Swells and Strong Rip Currents 360± feet Highly Sinuous Turbid water with up to 100 feet of expanded / accreted shoreline March 7, 2011 Intermediate High Tide / Windy / Choppy with Very Strong Southwest Swell 340± feet Moderately Sinuous with Relatively Steep Foreshore Turbid water with strong shore breaks and wave activity along Jetty April 24, 2010 High Tide / Windy / Choppy with Strong Westerly Swells 335± feet Relatively Straight to Slightly Irregular Shoreline appears to have receded slightly, but is still expanded relative to modern November 14, 2009 Intermediate Tide / Relatively Calm with South Swell 380± feet Slightly Sinuous / Irregular Apparent run up / wetted sand encroaching within 260± feet of site PA2022-0167
Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021 Proposed New Residence Construction Project No. 1-1201 2050 East Oceanfront Page 4 of 4 Newport Beach, California Date of Image Inferred Tide / Wind / Wave Conditions Width of Backshore Shoreline Configuration Other Notes October 22, 2007 High Tide / Windy / Moderately Choppy with Westerly Swell 330± feet Irregular Wave run up to within 375± feet of site December 31, 2005 High Tide / Apparent Offshore Winds / South-Southwesterly Swell 350± feet Smooth / Straight to the Northwest; Cuspate / Irregular to the Southeast Anomalous breaks offshore – maybe wind and/or current driven. August 18, 2005 High Tide / Windy with South Swell and High-Energy Shore Breaks 335± feet Slightly Sinuous / Highly Irregular High surf with run up to within 270± feet April 16, 2003 High Tide / Windy with Southwest Swell and Strong Rip Currents 350± feet Moderately Irregular High Surf / Shore Breaks December 31, 2002 Intermediate Low Tide / Calm Conditions 370± feet Relatively Straight Relatively Calm Conditions June 4, 2002 Intermediate High Tide / Moderate Southwest Swell 400± feet Irregular / Slightly Sinuous Moderate Surf PA2022-0167
Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront
Newport Beach, California
APPENDIX A
NOAA TIDES AND CURRENTS
DATUMS FOR 9410660, LOS ANGELES, CA
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Meteorological Obs. (/met.html?id=9410660)
Phys. Oceanography (/physocean.html?id=9410660) PORTS (/ports/ports.html?id=9410660)
(https://www.noaa.gov/) (/)
Home (/)/ Products (products.html)/ Datums (stations.html?type=Datums)/
9410660 Los Angeles, CA
Datums for 9410660, Los Angeles CA
NOTICE: All data values are relative to the NAVD88.
Elevations on NAVD88
Station: 9410660, Los Angeles, CA
Status: Accepted (Oct 7 2011)
Units: Feet
Control Station:
T.M.: 0
Epoch: (/datum_options.html#NTDE) 1983-2001
Datum: NAVD88
Datum Value Description
MHHW (/datum_options.html#MHHW)5.29 Mean Higher-High Water
MHW (/datum_options.html#MHW)4.55 Mean High Water
MTL (/datum_options.html#MTL)2.64 Mean Tide Level
MSL (/datum_options.html#MSL)2.62 Mean Sea Level
DTL (/datum_options.html#DTL)2.54 Mean Diurnal Tide Level
MLW (/datum_options.html#MLW)0.74 Mean Low Water
MLLW (/datum_options.html#MLLW)-0.20 Mean Lower-Low Water
NAVD88 (/datum_options.html)0.00 North American Vertical Datum of 1988
STND (/datum_options.html#STND)-4.03 Station Datum
GT (/datum_options.html#GT)5.49 Great Diurnal Range
MN (/datum_options.html#MN)3.81 Mean Range of Tide
DHQ (/datum_options.html#DHQ)0.74 Mean Diurnal High Water Inequality
Favorite Stations
Station Info Tides/Water Levels
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PA2022-0167
Datum Value Description
DLQ (/datum_options.html#DLQ)0.94 Mean Diurnal Low Water Inequality
HWI (/datum_options.html#HWI)5.14 Greenwich High Water Interval (in
hours)
LWI (/datum_options.html#LWI)11.21 Greenwich Low Water Interval (in hours)
Max Tide (/datum_options.html#MAXTIDE)7.72 Highest Observed Tide
Max Tide Date & Time
(/datum_options.html#MAXTIDEDT)
01/10/2005
16:12
Highest Observed Tide Date & Time
Min Tide (/datum_options.html#MINTIDE)-2.93 Lowest Observed Tide
Min Tide Date & Time (/datum_options.html#MINTIDEDT) 12/17/1933
08:00
Lowest Observed Tide Date & Time
HAT (/datum_options.html#HAT)7.14 Highest Astronomical Tide
HAT Date & Time 12/02/1990
16:06
HAT Date and Time
LAT (/datum_options.html#LAT)-2.18 Lowest Astronomical Tide
LAT Date & Time 01/01/1987
00:00
LAT Date and Time
Tidal Datum Analysis Periods
01/01/1983 - 12/31/2001
DHQ: 0.74
DLQ: 0.94
MN: 3.81 GT: 5.49
Datums for 9410660, Los Angeles, CA
All figures in feet relative to NAVD88
MHHW: 5.29
MHW: 4.55
DTL: 2.54MTL: 2.64MSL: 2.62
MLW: 0.74
MLLW: -0.2NAVD88: 0
Datums
0
1
2
3
4
5
NOAA/NOS/CO-OPS
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PA2022-0167
Showing datums for
Datum
Data Units
Epoch
NAVD88
Feet
Meters
Present (1983-2001)
Superseded (1960-1978)
Submit
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Products available at 9410660 Los Angeles, CA
TIDES/WATER LEVELS
Water Levels (/waterlevels.html?id=9410660)
NOAA Tide Predictions (/noaatidepredictions.html?id=9410660)
Harmonic Constituents (/harcon.html?id=9410660)
Sea Level Trends (/sltrends/sltrends_station.shtml?id=9410660)
Datums (/datums.html?id=9410660)
Bench Mark Sheets (/benchmarks.html?id=9410660)
Extreme Water Levels ( /est/est_station.shtml?stnid=9410660)
Reports (/reports.html?id=9410660)
METEOROLOGICAL/OTHER
Meteorological Observations (/met.html?id=9410660)
Water Temp/Conductivity
PORTS
Los Angeles/Long Beach PORTS (/ports/index.html?port=ll)
PORTS product page for Los Angeles (/ports/ports.html?id=9410660)
OPERATIONAL FORECAST SYSTEMS
9410660 Los Angeles, CA
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PA2022-0167
This station is not a member of OFS
INFORMATION
Station Home Page (/stationhome.html?id=9410660)
Data Inventory (/inventory.html?id=9410660)
Measurement Specifications (/measure.html)
Website Owner: Center for Operational Oceanographic Products and Services
National Oceanic and Atmospheric Administration (http://www.noaa.gov)
National Ocean Service (http://oceanservice.noaa.gov)
Privacy Policy (/privacy.html)
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Take Our Survey (/survey.html)
Freedom of Information Act (https://www.noaa.gov/foia-freedom-of-information-act)
Contact Us (/contact.html)
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PA2022-0167
Coastal Hazards Evaluation / Geologic Stability Report December 20, 2021
Proposed New Residence Construction Project No. 1-1201
2050 East Oceanfront
Newport Beach, California
APPENDIX B
OUR COAST, OUR FUTURE
SEA LEVEL RISE AND SCENARIO REPORT
350 Fischer Ave. Front Costa Mesa, CA 92626 P: 714 668 5600 www.G3SoilWorks.com
PA2022-0167
Our Coast, Our Future Sea Level Rise and Scenario Report
by Our Coast Our Future project
www.ourcoastourfuture.org Report created: Nov 29,2021 12:31 am(UTC)
This sea level rise and storm scenario report summarizes model results for the area you selected. This report was designed to
provide information to help you identify vulnerabilities to sea level rise and storm surges.
Area and Elevation Information
Area is the size of selected polygon, in square meters, acres and hectares, and Elevation is the average, minimum and
maximum elevation from the Digital Elevation Model (DEM) within the polgyon.
Area:200.95 m²
0.05 ac
0.02 ha
Projected Percent Area Flooded for the Selected Area
Values indicate the percentage of the selected area flooded for the Storm and Sea Level Rise Scenario combination. Areas of
open water are included in these percentages.
Storm
Scenario
100 yr
Storm n/a n/a n/a n/a n/a n/a n/a 12.9%46.3%n/a n/a 100%
20 yr
Storm n/a n/a n/a n/a n/a n/a n/a 3.5%46.3%n/a n/a 100%
Annual
Storm n/a n/a n/a n/a n/a n/a n/a n/a 24.4%n/a n/a 100%
No
Storm n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 100%
none 25 cm 50 cm 75 cm 100 cm 125 cm 150 cm 175 cm 200 cm 250 cm 300 cm 500 cm
Sea Level Rise Scenario
under 25% flooded 25-50%
flooded
50-75%
flooded
over 75%
flooded
1 / 2
PA2022-0167
Our Coast, Our Future Sea Level Rise and Scenario Report
by Our Coast Our Future project
www.ourcoastourfuture.org Report created: Nov 29,2021 12:31 am(UTC)
Map of Area
Powered by TCPDF (www.tcpdf.org)
2 / 2
PA2022-0167
Dec. 2021
Figure A2050 East Oceanfront Newport Beach, CA
Project No. 1-1201 SoilWorksG3
350 Fischer Ave. Front
Costa Mesa, CA 92626
Phone: (714) 668 5600
www.G3SoilWorks.com
100 cm Sea Level Rise - No Storm
Approximate Site Location
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
Source: Our Coast Our Future Hazard Map -
Scaled to 1” = 10,000”
Map Scale: 1inch = 833.33 feet
PA2022-0167
Dec. 2021
Figure B2050 East Oceanfront Newport Beach, CA
Project No. 1-1201 SoilWorksG3
350 Fischer Ave. Front
Costa Mesa, CA 92626
Phone: (714) 668 5600
www.G3SoilWorks.com
100 cm Sea Level Rise - 100 Year Storm
Approximate Site Location
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
Source: Our Coast Our Future Hazard Map -
Scaled to 1” = 10,000”
Map Scale: 1inch = 833.33 feet
PA2022-0167
Dec. 2021
Figure C2050 East Oceanfront Newport Beach, CA
Project No. 1-1201 SoilWorksG3
350 Fischer Ave. Front
Costa Mesa, CA 92626
Phone: (714) 668 5600
www.G3SoilWorks.com
200 cm Sea Level Rise - No Storm
Approximate Site Location
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
Source: Our Coast Our Future Hazard Map -
Scaled to 1” = 10,000”
Map Scale: 1inch = 833.33 feet
PA2022-0167
Dec. 2021
Figure D2050 East Oceanfront Newport Beach, CA
Project No. 1-1201 SoilWorksG3
350 Fischer Ave. Front
Costa Mesa, CA 92626
Phone: (714) 668 5600
www.G3SoilWorks.com
200 cm Seal Level Rise - 100 Year Storm
Approximate Site Location
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
0ft 208.33 833.33 ft
83.33 416.66N
1 inch = 833.33 feet
Source: Our Coast Our Future Hazard Map -
Scaled to 1” = 10,000”
Map Scale: 1inch = 833.33 feet
PA2022-0167