HomeMy WebLinkAboutPA2022-0254_20221101_Coastal Hazards Analysis Report dated 10-24-22 WILLIAM SIMPSON & ASSOCIATES, INC.
CONSULTING STRUCTURAL ENGINEERS
23 ORCHARD, SUITE 250 PH. (949) 206-9929
LAKE FOREST, CA 92630 FAX (949) 206-9955
www.wsase.com e-mail: Tmail@wsase.comT
Page | 1
October 24, 2022
76 Linda Isle
Newport Beach, CA 92660
RE: COASTAL HAZARDS ANALYSIS REPORT
Applicant: Marcus Hernandez
WSA Job #7738
Mr. Hernandez,
Pursuant to your request, William Simpson & Associates, Inc., (WSA) is pleased to provide
this report regarding Coastal Hazards Analysis for the proposed development at the subject site. The
site is adjacent to Newport Bay; thus, it may be subject to Coastal Hazards such as, flooding, wave
runup, and erosion. This study investigates the potential for the aforementioned hazards to impact
the proposed development on the site over the next 75 years and addresses compliance with Coastal
Hazards Analysis Report requirements and standard of NBMC Section 21.30.15.E.2.
STATEMENT OF THE PREPARER’S QUALIFICATIONS
Masoud Jafari, S.E., the preparer of this report, holding a Bachelor of Science Degree in
Structural Engineering from Tehran, Iran, is a Licensed Civil Engineer - Certificate No. C43673 -
and Structural Engineer - Certificate No. S3812 - by the State of California. He joined the company
in 1987 and is now partly the owner, serving as the principal in charge of the company. He has been
actively involved in the design and entitlement of waterfront developments such as custom homes,
seawalls, piers, platforms, floating docks and marinas for over 30 years.
All the above being said, Masoud Jafari, S.E. shall be considered a qualified preparer for the
Coastal Hazard Analysis Report on this project.
Requirements in Appendix A for Step 1:
Establish the project sea level rise range for the proposed project’s planning horizon
(life of project) using the current best available science.
The State of California Sea-Level Rise Guidance 2018 update developed by the Ocean
Protection Council in close coordination with Policy Advisory Committee with representation from
California Natural Resources Agency, the Governor’s Office of Planning and Research, and the
WILLIAM SIMPSON & ASSOCIATES, INC.
CONSULTING STRUCTURAL ENGINEERS
23 ORCHARD, SUITE 250 PH. (949) 206-9929
LAKE FOREST, CA 92630 FAX (949) 206-9955
www.wsase.com e-mail: Tmail@wsase.comT
Page | 2
California Energy Commission provides a bold, science-based methodology for state and local
governments to analyze and assess the risks associated with sea-level rise, and to incorporate Sea-
Level Rise into their planning, permitting, and investment decisions, and it is considered the current
best available science.
As reflected in the clouded area of the enclosed Table 28, based upon direct interpolation of
the data for Medium-High Risk Aversion and Low emissions 2090 & 2100 and, over the project’s
planning horizon of 75 years, the estimated Sea-Level Rise for year 2097 shall be 5.13’.
Using direct interpolation of the data for Medium-High Risk Aversion and High emissions
2090 & 2100 and, over the project’s planning horizon of 75 years, the estimated Sea-Level Rise for
year 2097 shall be 6.28’.
Based on the highest high tide of +7.7’ NAVD88, the above established Sea-Level Rise will
account for bay water level of +13.98’ NAVD88 for Medium-High Risk Aversion and High
emissions. For Medium-High Risk Aversion and Low emissions the bay water level would be
+12.83’ NAVD88.
Per City of Newport Beach Municipal Code standards, we have enclosed Table 28 with
interpolated data for High emissions 2090 & 2100 and Low Risk Aversion. Based on that
interpolation, the estimated Sea-Level Rise for year 2097 shall be approximately 3.05’, which is
much smaller than the governing estimated SLR for Medium-High Risk Aversion. Based on
the highest high tide of +7.88’MLLW (7.70’NAVD88) recorded in the project area, the above
established Sea-Level Rise will account for bay water level of +10.90’NAVD88.
Requirements in Appendix A for Step 2:
Determine how physical impacts from sea level rise may constrain the project site,
including erosion, structural and geologic stability, flooding, and inundation.
According to the enclosed Grading Plan C-1 the lowest finished elevation of the proposed
development shall be at +10.90’ NAVD88=+11.08’MLLW which follow the Base Flood Elevation
established for the area. Based on the SLR established in Step 1 above, 1st floor of the proposed
structure will remain above High Tide sea level approximately until 2060 upon Medium-High Risk
Aversion probabilistic projections and until 2100 upon Low Risk Aversion probabilistic projections.
As we well know, majority of the public streets in Newport Bay area are currently at much lower
elevations than the subject site and they will flood due to SLR way before the development on this
site becomes subject to flooding.
FLOODING HAZARD
The primary hazard due to flooding from the ocean waters for this site, like majority of the sites
located adjacent to Newport Bay, would be due to long term Sea-Level Rise. The current water
levels in Newport Bay are reflected on the enclosed Datums for Newport Bay Entrance.
WILLIAM SIMPSON & ASSOCIATES, INC.
CONSULTING STRUCTURAL ENGINEERS
23 ORCHARD, SUITE 250 PH. (949) 206-9929
LAKE FOREST, CA 92630 FAX (949) 206-9955
www.wsase.com e-mail: Tmail@wsase.comT
Page | 3
While Sea-Levels have been rising for decades, higher rates of raise are forecast for the
coming century because of climate change – see enclosed table 28. Increases can be attributed to
warmer temperatures, which cause water to expand, as well more liquid mass caused by melting of
ice caps. Current estimates of future SLR generally fall in the range of 5.4-6.7 ft for the year 2100.
Global warming may impact flooding in other ways as well. Warmer water could intensify North
Pacific storms, bringing greater wind and wave energy to shoreline in winter and higher intensity
precipitation.
The Newport Beach Peninsula portion of the Pacific Institute California Flood Risk Map is
shown herein as OE S Quadrangle. The dark blue colored areas show the areas where a 100-year
Sea-Level Rise of 55 inches is added to the existing FEMA coastal flood elevation shown in light
blue. Obviously, the entire Newport Bay area will be affected if sea level rises 55 inches by the year
2100.
If the sea level rises in the next several decades as currently estimated, regional measures to
mitigate the potential flooding hazard shall be taken. Since top of the new stem wall is at +10.9’
NAVD88, it will remain above the high tide approximately until year 2070. In the event that
SLR prediction of 6.00’ for year of 2095 holds true, the concrete deck shall accommodate raise
to top of wall elevation of +13.7’NAVD88, as reflected on the enclosed S-2.
WAVE RUNUP
Wave runup is the uprush of water from wave action on a shore barrier intercepting
Stillwater level. On steeply sloped shorelines, the rush of water up the surface of the natural beach,
including dunes and bluffs, or the surface of a manmade structure, such as revetment or vertical wall
can result in flood elevations higher than those of the crest of wind-driven waves. See wave Runup
Sketch below.
Due to its location, this site is not a subject to typical ocean waves and the associated wave
runup. For sake of narrow width of the channel and wake restrictions, significant wave or boat wake
is not expected. Small wave or small boat wake waves are generally dampened by the moored
vessels and dock systems located in front of the site and have no significant energy and runup effect.
WILLIAM SIMPSON & ASSOCIATES, INC.
CONSULTING STRUCTURAL ENGINEERS
23 ORCHARD, SUITE 250 PH. (949) 206-9929
LAKE FOREST, CA 92630 FAX (949) 206-9955
www.wsase.com e-mail: Tmail@wsase.comT
Page | 4
Tsunami type waves that approach from the ocean shoreline will likely not reach the site for
several reasons. There is no significant near field source of a tsunami like the geologic conditions of
some other places on Earth such as Japan, for example. A far field tsunami reaching the ocean
shoreline will likely not reach the site because of the distance and developments between the
shoreline and this site. Due to its very infrequent occurrence – 500-year recurrence interval –
tsunami should not be considered a significant impact over the life of the proposed structure -
75 years.
EROSION HAZARD
Erosion refers to the wearing or washing away of coastal lands. Beach erosion is a chronic
problem along many open ocean shores of the United States. To meet the needs for comprehensive
analysis of shoreline movement, the United States Geological Survey has conducted analysis of
historical shoreline changes along open ocean sandy shores of the conterminous United States and
has produced an Open-File Report 2006-1219 entitled “National Assessment of Shoreline Change
Part 3: Historical Shoreline Change and Associated Coastal land Loss Along Sandy Shorelines of the
California Coast”. The report looks at survey data of the following periods: 1800s, 1920s-1930s, and
1950s-1970s, whereas the lidar shoreline is from 1998-2002. The report looks at both long-term and
short-term changes. According to the report, the average rate of long-term shoreline change for the
State of California was 0.2±0.1 m/yr., and accretional trend. The average rate of short-term
shoreline change for the state was erosional; with an average rate of -0.2±0.4 m/yr. The seawall
location of this site is stabilized and not subject to significant long-term erosion. Review and
analysis of historical aerial photographs and field measurements for seawall repairs in the area show
no change in the position of the shoreline over the last several decades. The future shoreline changes
over the next 75 years are assumed to be the same as in the previous several decades. However,
there is a rapid rate of sea level rise predicted in the next 75 years. If that prediction holds true,
the rapid sea level rise may accelerate shoreline erosion, but it shall not impact the structure
on the subject lot over its economic life due site location.
CONCLUSION
In conclusion, flooding, wave runup and erosion will not significantly impact this property
over the proposed life of the development. The existing seawall/bulkhead is required to protect the
proposed structures on the lot, the adjacent properties, public facilities and infrastructure; thus, it can’t
be removed. Removal of the seawall/bulkhead will result in erosion and undermining the foundations
of the structures and site walls at the subject site and both adjacent sites. Once the existing
seawall/bulkhead is repaired/reinforced in compliance with the enclosed drawings S-2, need for a new
shoreline protective devise shall not anticipated over the economic life of the proposed development to
protect it from flooding, wave runup or erosion. Waterproofing flashing or waterproofing curbs around
the perimeter of habitable rooms shall not be required. If found not adequate for the actual sea level
rise over the next 75 years, the existing seawall/bulkhead assembly, including the concrete wall at the
entire bayward edge of the new concrete deck, allows to be increased in height to+13.7’NAVD88
without further seaward encroachment. If during this period the seawall/bulkhead displays any sign of
distress that requires immediate attention, due to some unforeseen catastrophic or disastrous events, it
WILLIAM SIMPSON & ASSOCIATES, INC.
CONSULTING STRUCTURAL ENGINEERS
23 ORCHARD, SUITE 250 PH. (949) 206-9929
LAKE FOREST, CA 92630 FAX (949) 206-9955
www.wsase.com e-mail: Tmail@wsase.comT
Page | 5
should be repaired or replaced at that time accordingly, without seaward encroachment from its current
location.
The above conclusion was prepared based on the existing conditions, proposed drawings,
current projection of future sea level rise, and within the inherent limitations of this study, in
accordance with generally acceptable engineering principles and practices. We make no further
warranty, either expressed or implied.
William Simpson & Associates, Inc. appreciates the opportunity to work with you towards
the successful completion of your project. Should you have any questions regarding this report,
please give us a call.
Respectfully submitted,
Masoud Jafari, S.E.
Principal
Enclosures:
Location Map
Aerial View
Topographic Survey
Structural Drawings
Table 28: Projected Sea-Level Rise (in feet)
Datum for Newport Bay Entrance
Figure 3.1
Figure 3.2
California Flood Risk: Newport Beach OE S Quadrangle
FEMA Flood Risk
F.F.=10.90
T/SLAB=10.78
PAD=__.__
POOL
WF
CONSTRUCTION NOTES
DISPOSITION NOTES
DISPOSITION NOTES
1 3 9 A v e n i d a N a v a r r o
San Cle m en te , CA 92672
9 4 9 .4 9 2 .8 5 8 6
www.toalengineering.com
C I V I L EN G I NE ER I NG
L A N D S U R V E Y I N G
STORMWATER QUALITY
ADAM L. TOAL
R.C.E. 59275
DATE:
LEGEND
SCOPE OF WORK
ADDITIONAL NOTES
EASEMENT NOTESCITY OF NEWPORT BEACH NOTES
BENCHMARK NOTE:
OCSBM 3K-24A-82
ELEV=19.353
NAVD88 DATUM, 2015 ADJ.
EASEMENT NOTE:
ALL EASEMENTS SHOWN ON THIS TOPOGRAPHIC AND BOUNDARY
SURVEY ARE PER A PRELIMINARY TITLE REPORT PREPARED BY LAWYERS
TITLE COMPANY, ORDER NO. FLNP-0062200998GH DATED AUGUST 18, 2022
UNLESS NOTED OTHERWISE.
7 ITEM 7 OF THE PRELIMINARY TITLE REPORT, AN EASEMENT FOR
AVIGATION RIGHTS RECORDED IN BOOK 6965, PAGE 721 O.R. IS
BLANKET IN NATURE AND NOT PLOTTED HEREON.
8 ITEM 8 OF THE PRELIMINARY TITLE REPORT, EASEMENTS FOR
WALKWAY, PARKING AND PLANTER PURPOSES RECORDED IN BOOK
8938, PAGE 91 AND RE-RECORDED IN BOOK 9224, PAGE 1, BOTH O.R.
PROPERTY IS NOW OWNED IN FEE TITLE AND THE EASEMENTS ARE
NO LONGER IN EFFECT. AN EASEMENT FOR PRIVATE PIER
CONSTRUCTION AND MAINTENANCE, AND FLOAT IN, UNDER AND
ACROSS A PORTION OF LOT A, TRACT 4003 PLOTTED HEREON.
9 ITEM 9 OF THE PRELIMINARY TITLE REPORT, EASEMENTS FOR
UTILITY PURPOSES LISTED WITHIN THE CC&R'S RECORDED IN BOOK
9771, PAGE 488 O.R. HAVE NO SPECIFIC LOCATION AND ARE NOT
PLOTTED HEREON. EASEMENTS FOR WALKWAY, PARKING AND
PLANTER PURPOSES LISTED IN THE SAME DOCUMENT ARE
PLOTTED HEREON.
10 ITEM 10 OF THE PRELIMINARY TITLE REPORT, EASEMENTS FOR
UTILITY, DRAINAGE, MAINTENANCE AND OTHER PURPOSES
RECORDED IN BOOK 12956, PAGE 910 O.R. ARE NOT PLOTTED
HEREON, THE COPY OF THE RECORDED DOCUMENT IS ILLEGIBLE.
THE EASEMENTS MAY BE COLLINEAR WITH OTHER EASEMENTS LIST
IN THE PRELIMINARY TITLE REPORT.
A PARCEL B OF THE LEGAL DESCRIPTION IN THE PRELIMINARY TITLE
REPORT, AN EASEMENT FOR PRIVATE PIER CONSTRUCTION AND
MAINTENANCE, AND FLOAT IN, UNDER AND ACROSS A PORTION OF
LOT A, TRACT 4003 JOB NO.SHEET
1 3 9 A v e n i d a N a v a r r o
S a n C le me n t e , C A 9 2 6 7 2
9 4 9 .4 9 2 .8 5 8 6
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C I V I L E N G I N E E R I N G
L A N D S U R V E Y I N G
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TABLE 28: Projected Sea-Level Rise (in feet) for Los Angeles
Probabilistic projections for the height of sea-level rise shown below, along with the
H++ scenario (depicted in blue in the far right column), as seen in the Rising Seas
Report. The H++ projection is a single scenario and does not have an associated
likelihood of occurrence as do the probabilistic projections. Probabilistic projections
are with respect to a baseline of the year 2000, or more specifically the average
relative sea level over 1991 - 2009. High emissions represents RCP 8.5; low emissions
represents RCP 2.6. Recommended projections for use in low, medium-high and
extreme risk aversion decisions are outlined in blue boxes below.
Probabilistic Projections (in feet) (based on Kopp et al. 2014)
MEDIAN LIKELY RANGE 1-IN-20 CHANCE 1-IN-200 CHANCE
50% probability
sea-level rise meets
or exceeds…
66% probability
sea-level rise
is between…
5% probability
sea-level rise meets
or exceeds…
0.5% probability
sea-level rise meets
or exceeds…
H++ scenario (Sweet et al. 2017) *Single
scenario
Low
Risk
Aversion
Medium - High
Risk Aversion
Extreme
Risk Aversion
High emissions 2030 0.3 0.2 -0.5 0.6 0.7 1.0
2040 0.5 0.4 -0.7 0.9 1.2 1.7
2050 0.7 0.5 -1.0 1.2 1.8 2.6
Low emissions 2060 0.8 0.5 -1.1 1.4 2.2
High emissions 2060 1.0 0.7 -1.3 1.7 2.5 3.7
Low emissions 2070 0.9 0.6 -1.3 1.8 2.9
High emissions 2070 1.2 0.8 -1.7 2.2 3.3 5.0
Low emissions 2080 1.0 0.6 -1.6 2.1 3.6
High emissions 2080 1.5 1.0 -2.2 2.8 4.3 6.4
Low emissions 2090 1.2 0.7 -1.8 2.5 4.5
High emissions 2090 1.8 1.2 -2.7 3.4 5.3 8.0
Low emissions 2100 1.3 0.7 -2.1 3.0 5.4
High emissions 2100 2.2 1.3 -3.2 4.1 6.7 9.9
Low emissions 2110* 1.4 0.9 -2.2 3.1 6.0
High emissions 2110* 2.3 1.6 -3.3 4.3 7.1 11.5
Low emissions 2120 1.5 0.9 -2.5 3.6 7.1
High emissions 2120 2.7 1.8 -3.8 5.0 8.3 13.8
Low emissions 2130 1.7 0.9 -2.8 4.0 8.1
High emissions 2130 3.0 2.0 -4.3 5.7 9.7 16.1
Low emissions 2140 1.8 0.9 -3.0 4.5 9.2
High emissions 2140 3.3 2.2 -4.9 6.5 11.1 18.7
Low emissions 2150 1.9 0.9 -3.3 5.1 10.6
High emissions 2150 3.7 2.4 -5.4 7.3 12.7 21.5
S T A T E O F C A L I F O R N I A S E A - L E V E L R I S E G U I D A N C E
*Most of the available climate model experiments do not extend beyond 2100. The resulting
reduction in model availability causes a small dip in projections between 2100 and 2110, as well as
a shift in uncertainty estimates (see Kopp et al. 2014). Use of 2110 projections should be done with
caution and with acknowledgement of increased uncertainty around these projections.
A P P E N D I X 3 : S E A - L E V E L R I S E P R O J E C T I O N S F O R A L L 1 2 T I D E G A U G E S | 7 2
Newport BeachNewport Beach
Costa MesaCosta MesaCosta MesaCosta MesaHuntington BeachHuntington Beach
¬«1
¬«55
¬«1
¬«55
117°52’30"W
117°52’30"W
117°55’0"W
117°55’0"W
117°57’30"W
117°57’30"W
118°0’0"W
118°0’0"W
33°37’30"N
33°37’30"N
33°35’0"N
33°35’0"N
33°32’30"N
33°32’30"N
33°30’0"N
33°30’0"N
407000mE
407000mE
08
08
09
09
410
410
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
419000mE
419000mE
37
07
00
0
m
N
37
07
00
0
m
N
08 08
09 09
3710 3710
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
3720 3720
37
21
00
0
m
N
37
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00
0
m
N
This information is being made available for informational purposes only. Users of this information
agree by their use to hold blameless the State of California, and its respective officers, employees,
agents, contractors, and subcontractors for any liability associated with its use in any form. This work
shall not be used to assess actual coastal hazards, insurance requirements, or property values
and specifically shall not be used in lieu of Flood Insurance Studies and Flood Insurance Rate Maps
issued by the Federal Emergency Management Agency (FEMA).
Data Sources: US Geological Survey, Department of Commerce (DOC), National Oceanic and Atmospheric
Administration (NOAA), National Ocean Service (NOS), Coastal ServicesCenter (CSC), Scripps Institution
of Oceanography, Phillip WIlliams and Associates, Inc. (PWA), US Department of Agriculture (USDA),
California Coastal Commission, and National Aeronautics and Space Administration (NASA). Imagery from ESRI and i-cubed.
Created by the Pacific Institute, Oakland, California, 2009.
California Flood Risk: Sea Level Rise
00.511.520.25
Miles
01230.5
Kilometers
1:
2:
3:
4:
5:
6:
7:
8:
Seal Beach
Newport Beach
Tustin
not printed
Laguna Beach
not printed
not printed
not printed867
1 2 3
54
§¨¦
£¤
")
¬«
Interstate
US Highway
State Highway
County Highway
Grid coordinates:
UTM Zone 11N meters
Adjoining Quadrangles:
Map extents match USGS 7.5 minute topographic maps
Project funded by the California Energy Commission’s
Public Interest Energy Research Program, CalTrans,
and the California Ocean Protection Council
Newport Beach OE S Quadrangle
NAD83 GCS degrees
Coastal Zone Boundary
Current Coastal Base Flood
(approximate 100-year flood extent)
Sea Level Rise Scenario
Coastal Base Flood + 1.4 meters (55 inches)
Landward Limit of
Erosion High Hazard Zone in 2100
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250
Feet
Ü
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AREAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or DepthZone AE, AO, AH, VE, AR
Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mileZone X
Future Conditions 1% Annual
Chance Flood HazardZone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREENArea of Minimal Flood Hazard Zone X
Area of Undetermined Flood HazardZone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.The basemap shown complies with FEMA's basemapaccuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 3/15/2022 at 4:48 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear: basemap imagery, flood zone labels,
legend, scale bar, map creation date, community identifiers,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.
Legend
OTHER AREAS OF
FLOOD HAZARD
OTHER AREAS
GENERAL
STRUCTURES
OTHER
FEATURES
MAP PANELS
8
B 20.2
The pin displayed on the map is an approximatepoint selected by the user and does not representan authoritative property location.
1:6,000
117°54'27"W 33°37'7"N
117°53'50"W 33°36'37"N
Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020