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Home My WebLink About20170130_Coastal Hazards Analysis_12-14-2016WILLIAM SIMPSON & ASSOCIATES, INC. CONSULTING STRUCTURAL ENGINEERS 23 ORCHARD, SUITE 250 LAKE FOREST, CA 92630 www.wsase.com December 14,2016 Ian Harrison PH. (949) 206-9929 FAX (949) 206-9955 e-mail: ma i l@wsase .com 3535 east Coast Hwy #301 Corona Del Mar, CA 92625 RE: 2772 Bayshore Drive, Newport Beach (Orange County), Location Coastal Development Permit Application WSA Job #7084 Dear Mr. Harrison, Pursuant to your request and authorization by the owner of the property, William Simpson & Associates, Inc., (WSA) is pleased to provide this report regarding Coastal Hazards Analysis for the proposed new development at the subject site. The site is adjacent to Newport Bay waters, 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 to 100 years. FLOODING HAZARD The primary hazard due to flooding from the bay 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 Tide Planes & Tidal Datum-City ofNewport Beach STD-599-L. According to the enclosed drawings S-0, S-1 & S-2 for the proposed Seawall Repair/Reinforcing, top of existing stem wall on top of bulkhead coping is at+ 12.68' NA VD88 (North American Vertical Datum 1988). First floor finish elevation of the proposed development is at + 12.80' NA VD88 in accordance with the attached Site Plan C-1. The highest high tides in Newport Beach threaten flooding of low-lying terrain. Historically, the highest high tides have reached approximately 7.8 ft above MLL W. This has occurred twice: January 28, 1983 and January 10, 2005. While sea levels have been rising for decades, higher rates of raise are forecast for the corning century as a consequence of climate change - see enclosed Sea Level Change Graph. 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 sea level rise generally fall in the range of 1-3ft for the year 2100. A United States Environmental Protection Agency study puts these figures in a probabilistic perspective, suggesting there was a 50% chance that sea level rise would exceed 0.4, 0.7 and 1.5 ft by 2025,2050 and 2100, respectively, and a 10% chance that sea level rise would exceed 0.6, 1.1 and 2.9 ft by 2025,2050 and 2100, respectively. On August 12, 2015, California Coastal Commission unanimously adopted Sea Level Rise Policy I PA2017-019 Guidance: Interpretive Guidelines for Addressing Sea Level Rise in Local Coastal Programs and Coastal Development Permits. According to this Document, considered The Best Available Science and Consequences of Sea Level Rise, the sea-level rise projections for California (NRC 2012) are 1, 2 and 5.5 ft by 2030, 2050 and 2100 respectively. 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. In order to review the historical tides, FlowSimulations, LLC has obtained tide heights data form the NOAA (National Oceanic and Atmospheric Administration) Center for Operational Oceanographic Products and Services (CO-OPS) "Tides and Currents" website, http://co- ops.nos.noaa.gov/ (Data accessed April, 2008). Year-long records of hourly tide predictions and measurements for Station ID: 9410660 (Los Angeles) have been accessed for 1982-2007. In addition, year-long records of hourly tide predictions have been accessed for 2008-2020. All tide heights have been saved in units offeet relative to MLLW and relative to GMT (Greenwich Mean Time). Los Angeles has been chosen because it is the nearest NOAA tide station with tide measurement data. A review of benchmark data for Los Angeles versus Newport Harbor shows that tide heights typically differ by less than an inch. For example, NOAA benchmarks data reports than the mean tide range at Newport Beach harbor is 3.76 ft versus 3.81 ft at Los Angeles, a difference of 0.05 ft or 0.6 inches. Hourly NTRs (Non-Tide Residuals) have been obtained for years 1982-2007 by subtracting the predicted tide heights from the measured tide heights. Positive NTR corresponds to higher tides than predicted and negative NTR correspond to lower tides than predicted. To characterize the magnitude and frequency of historical NTRs during the winter season when maximum astronomical tides occur, hourly NTRs for the months of December, January and February have been compiled for each year between 1982/83 and 2006/07 and rank ordered. From this ranking the 98111 percentile NTRs have been extracted; this corresponds to 2% exceedance probability. To further explore the association between NTR and strong El Nino conditions, the 981h percentile NTR for each winter (2% exceedance probability) has been plotted versus ONI (Oceanic Nino Index) as shown in the enclosed Figure 3.1 and positive correlation has been identified (R2 =0.72, p<0.05). The implication for coastal flooding is not only that the probability of coastal flooding, or flood risk, varies from year to year depending on climatic conditions in addition to astronomical factors, but that the stronger El Nino the greater the coastal flood risk. There are important exceptions to this trend, however. Figure 3.1 shows two instances where NTR exceeded 0.5 ft even though ONI values have been between 0 and 1 °C corresponding to El Nino neutral or weak El Nino conditions. On the other hand, Figure 3.1 also shows that 2% exceedance probability NTR values never exceeded 0.5 ft when ONI values have been less than zero (i.e., during La Nina conditions). This suggests that coastal flood risk is minimized during La Nina conditions. The enclosed Figure 3.2 shows the height of monthly maximum high tides through 2020 based on astronomical factors. There are two peaks per year corresponding to maximum high tides in summer and winter. The graph in Figure 3.2 also reflects the 4.4-year cycle reported by Zetler and Flick (1985) and Flick (1986). The Newpmt 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 1 00-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 66 inches (5.5 feet) 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 the top of slab at the proposed development is lower than 7.8' + 5.5'=13.3' NAVD88, the existing seawall will have to be raised in accordance with enclosed STD-601-L in order to accommodate the actual see level at that time. PA2017-019 WAVERUNUP Due to its location, this site is not a subject to typical ocean waves and the associated wave runup. Bay generated waves that may arrive at this site are very small wind waves and boat wakes. These types of waves are generally dampened by the moored vessels and dock systems located in front of the site, and have no significant energy and run up effect. 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. A near or far field tsunami propagating into Newport Bay proper would likely cause a seiche or standing wave on the order of 1.5 feet traveling within the bay. Even at the highest anticipated tide in Newport Beach of +7.8'LMMW this shall not result in overtopping of the bulkhead. 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 to100 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. In order 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 beach footprint 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 7 5 to I 00 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 to 100 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. CONCLUSION In conclusion, flooding, wave runup and erosion will not significantly impact this property over the proposed life of the development. Once the existing seawall/bulkhead gets repaired/reinforced in compliance with the enclosed drawings S-0, S-1 & S-2, need for a new shoreline protective devise is not anticipated over the economic life of the proposed development to protect it from flooding, wave run up or erosion. If found not adequate for the actual sea level rise over the next 75 to 100 years, the bulkhead assembly allows to be increased in height without further seaward encroachment. 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. PA2017-019 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, Plamen Petrov, P.E. Senior Project Manager Enclosures: Location Map Aerial View Masoud Jafari, S.E. Principal City of Newport Beach Tide Planes & Tidal Datum -STD 599-L Seawall Drawings S-0, S-1 & S-2 Site Plan C-1 Sea Level Change Graph Figure 3.1 Figure 3.2 City ofNewport Beach Detail for Raising Bulkheads-STD 60 1-L Newport Beach OE S Quadrangle PA2017-019 w. WILLIAM SIMPSON & ASSOCIATES. INC. ~ CONSULTING STRUCTURAL ENGINEERS 2772 BA YSHORE DRIVE NEWPORT BEACH, CA 92663 JOB. 7084 SHT. 23 ORCHARD. SUITE 250 LAKE FOREST, CA 92630 ( ) DES. PBP p 949 206-9929 1-------------------j------ F (949) 206-9955 OA TE 12/14/16 C\\" lcDo nald's PROJECT SITE Southwind Kt~ya k 0 Cen ter Rental Base SOL Mexican Cocina 1 Newport Beach ~ ~ ~- 3 Thirty 3 W aterlront 9Q ~--~~-~ 2772 Hayshor• Drive 2 ~1 f'Tlirt driw" '1" rni' Lower Newport Bay Linda Island Unds Isle Harbo r JsJand LOCATION MAP 0 PA2017-019 '\lL WILLIAM SIMPSON & ASSOCIATES, INC. ~ CONSULTING STRUCTURAL ENGINEERS 2772 BA YSHORE DRIVE NEWPORT BEACH, CA 92663 JOB. 7084 SHT. 23 ORCHARD, SUITE 250 LAKE FOREST, CA 92630 P {949) 206-9929 1-------------------+-D_Es_._P-=.B_P __ _ F (949) 206-9955 DATE 12/14/16 AERIAL VIEW PA2017-019 Tide Planes and Tidal Datum Relation.sbips (U.S. Survey Foot) Theory #1 -Tidelands lie between mean high and mean of low neap tides. Theory #2-Tidelands lie between mean of all high and mean of all low tides. lnfonnation was taken from National Ocean Service (NOS), Office of Ocean and Earth Science (OES), Tidal Datum sheet. Publication Date 07/17/89 CITY OF NEWPORT BEACH APPROVED: BUILDING DEPARTMENT RELATIONSHIPS ~-'D=•'=e: ru=L=Y=2o::.co4_..J.__S_ca_e:_N_._T_.S_._1 (U.S. SURVEY FOOT) DRAWINGNO. STD-599-L ~ ~----~~--------------~~------L-----------------------~ PA2017-019 " . -~! -en i! !~~:I!' Ol 0 ¥~0 0 ~g li~·· .31 ~~~ ~ -.(~ _;:;e,. X .,. §~ ~id ~§ < ~ a! " ~" n ~ ~~li ~ ~l~~~iiEI '" ~~~ ~ ~i ~;~i ~ II ~~i 0 < ~;~!hi} x m ~~· :a n ·~ !l§ X~ '" iii~~ z ~~ a--~; !' ·~g =4 !ls sX; · 2 ~ -< •-o ~i; I;~ n 1: "• • p~ ~~-01 ~ l5:~ ., ~6 §.! xs ~~ :r -~-~ } ~ ~~ -o·~ ~~ l ~~ ~~ niHx i~ i J~o ~.~ ~ -~ . ~ -7084 s-o I' i .. ~ WILLIAM SIMPSO'" & ASSOCIATES, INC. CONSULnNG SlRUClURAL ENGINEERS U OIIOIAI!D .... I(1)0 ~Ml r(llll(tl '" tU·» ,,,,,,201_..,,. r(totiXII-t'!l~ RIINfORCIHO THI! I!XISn NO S!AWALL LOCATED .U, 2772 BAY&HOAE DRIVE N!WPORT B!ACH, CA 92883 STRUCT CENERAL NOTES & \'\ONITY WAP Ow.-.IER / APPUCANT Mr. Kevin Moriarty 2782 Bayshore Drive Newport Beach, CA 92663 Phone. 19491 300•0310 (J) -t :a c 0 -t c :a :1> r- G> m z m :a :1> r- z 0 -t m CJ) _, __ , ---.. -..·------.. =~~!:i~--t:--:?- PA2017-019 ,., •tnlll-"' c .. :II :z: m ,. g m 5 ,. -4 0 z < -7084 8·1 I I I r--- ' I I r----- ' I I r----- ' I I r--- ' I I r--- ss :a :a I x ~ i ~ ~ p s ; ~ ~ 5 l ~ i tn :::; m '11 .. ,. z o_ .. ii ~~--__:__----=-~~~. 11=--------- n 11 0 n II II II II II II II II ~ 11 -----------~========= =' .:=-= ~~~:,-----~·~···~·~··~-----J I !•n ~ ~~~ _!!,.!!__ .~~ g l~ i~~ , I , i ~ I) ~ WILLIAM S IMPSON &. ASSOCIATES, INC. CONSULnNG STRUCTURAL ENGINEERS lJOIIO<ARO,SUI'tl=-<1 L~f0A£ST,0.~21UQ ~(t4t):X.·HH '(to'J)'JOI-IIU ... ..a ..... "._ RIINII'ORCIHQ THI! II!KI8TINQ UAWAL.L LOCATIED AT• 2772 BA YSHORE DRIVE NEWPORT BEACH, CA 92003 SITE PlAN & ELEVA nON --+-- OWNER / APPLICANT Mr. Kevin Moriarty 2782 Bayshore Drive Newport Beach, CA 92663 Phone. 19491 300-0310 N -J -J iii~ N Ill 0§~ ,. -< -~ '~; ~ q~. 0 1 =i~ :<! "' • ~0~ 0 "~ :<! < "' PA2017-019 .,, " I~ - - • 8 i ! i re-___ '----~1.·~~: . .:· [-'-ILLIIIT~~~~,, ... -l ... : ,H ~ WILLIAM SIMPSON , & ASSOCIATES, INC. CONSULllNO STRUCTURAL ENGINEERS """"''"·'"'"''" ""''"""'·'"'""" i 1 I I I I I Mr. Kevin Moriarty 2782 Bayshore Drive Newport Beach, CA 92663 Phone. 19491 300•0310 PA2017-019 MORJARTY POOL HOUSE 2m BAY SHORE DRJVE NEWPORT BEACH, CALIFORNIA 92663 BAYSHOR.E DR.JVE ----!~-----:· II tl <;=--o===-0.-·=T~--.;::::.·.·::::: I !) ' ' ' ----------------· :::::::::::::::::::::. NEWPOR.THAR.BOR. SITE PLAN PROJECT DATA PA2017-019 7.0 I ... OPC High • OPCLow 6.0 -t-• CA Coastal Conservancy -USACE I NRC Ill I Vermeer and Rahmstorf g 5.0 Mean and Range 0 .-4 0 I Note: see text for descriptions N ... ofA1FI, A2, 81 andAR4 Ill (II > 0 4.0 .. (II > ~ .!!! (II «: (II ~ 3.0 Ill ~ u Qj > (II -I 2.0 Ill (II II) I ~ ~ • I I AR4 ~ -~ 1.0 0.0 ~ ~ I I I I 2010 I I I I 2020 2030 2040 2050 2060 2070 2080 2090 2100 Year Figure 3.3 Comparison of USACE/NRC Ill Projections of Sea Level Rise with Vermeer and Rahmstorf (2009), (Adopted from Vermeer and Rahmstorf 2009) and OPC and California State Coastal Conservancy Recommendations PA2017-019 Los Angeles, 1982/83-2006/07 1.5.---------~--------.---------•. ---------,----------.-------~ 1 - fl <:: -l!l o.s r ~ <J! N ~ 01- 0: !z .c ~ I iij 7 -0.5 0 ll) D -1L---------~·--------~·--------~~~------~·----------L-------~ ~ ~ ~ 0 1 2 3 Oceanic Nmo Index (ON!} rar Dec-Jan-Feb fC) Figure 3. 1. A plot of 2% exceeaance probability NTR versus ONI shows significant correlation (R2=0.72, p<0.05), but note that NTR exceeding 0.5 ft have also occurred during weak El Nino and El Nino neutral winters (O<ONI<l). PA2017-019 7.5,---~,--~,,---.-,--,----r--~--~.----r-,--,----.-,--~---r---, 71- [\ 6 S.SL---~'---'~--L-'--~--~---~1 --~'~--~~--~----~'--~'----~~ 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Figure 3.2. Monthly maximum high tides for Los Angeles between 2008 and 2020. There are two peaks per year corresponding to maximum high tides in summer and winter. Note also the 4.4 year cycle reported by Zetler and Flick (1985) and Flick (1986). PA2017-019 NOTE: 2-#4 CONT. EPOXY-COATED -~ PER ASTM A934 8" CONCRETE BLOCK WALL ADDED TO TOP OF EXISTING BULKHEAD #5 @ 24" O.C. DRILL AND EPOXY BARS PER-----...._ MANUFACTURER'S RECOMMENDATIONS INTO EXISTING COPING TOP OF IMPROVEMENTS 6" EXISTING TIE ROD ALTERNATE "A" (CONCRETE BLOCK) 1 1/2" CHAMFER (1YPICAL) -----------.. #4 CONT. EPOXY COATED A934 -------.... CONCRETE: f 'c = 4,500 PSI (MIN.)----.._ W /C RATIO = 0.45 (MAX.) #5 @ 24" O.C. DRILL AND EPOXY BARS PER MANUFACTURER'S RECOMMENDATIONS INTO EXISTING COPING ALTERNATE "B" (POURED-IN-PLACE CONCRETE) EPOXY SHALL CONFORM TO ASTM C881 STANDARD AND BE USED IN STRICT ACCORD WITH THE MANUFACTURERS PRINTED INSTRUCTIONS. PROPERTY, BULKHEAD OR OTHER BAYWARD LIMIT ROUGHEN FOR BOND AND APPLY EPOXY EXISTING COPING EXISTING BULKHEAD PROPERTY, BULKHEAD OR OTHER BAYWARD LIMIT ELEVATION + 9.0 M.L.L.W. ROUGHEN FOR BOND AND APPLY EPOXY BONDING AGENT PER MANUFACTURER'S RECOMMENDATIONS. EXISTING COPING -' -'-0 ~ -6 ~ 0 REV. 11/07 ~ ~-------------------------------------------,------~~~~~~~~~~~~~~~9 CITY OF NEWPORT BEACH APPROVED:! I ~ BUILDING DEPARTMENT g ~------------------------------------------~ ~----~=-~~~~~~------~·;' DETAIL FOR RAISING BULKHEADS BUILDING DIRECTOR \.1 r-~~--~~~---.----------------~l Drawn: R. OKADA S l N T S .,. Date: JULY 2004 Ca e: . . . ~ ~--~~~~~--~----------------~a STD-601 -L ~ DRAWING NO. PA2017-019 PAC IFIC I NS"I ITUT£ California Flood Risk: Sea Level Rise Newport Beach OE S Quadrangle • ~ ~ CO.i!M!ZOtll~ Thi111'1form.IICII'I• being ~~U~dil 8Yiil&ble lor lnl'orm~~~•l purpowa oNy. UMra d We; irlfornwlllofl agtM by ~Mit Ule\0 ~~MIMS~t•dtd1~. a"" b r•speetN•~. eq,loY9ft.. agent•.~•.encJ~®ttbtnrllbityassodated....m~~:~userna~~ylottT'l TI'IJiwolk 51'1 .. no1 M UMCI 10 ....... ~Uilll e<»ml hauRb,IMWanot reQUft/MOts, or property values m ~~ •t~e•noc bt uMd ill itu ol Flood lnsl.l!'ai'Q Sludlu and Flood lnt.Uflll'IOI Ra:e Maps iuu~b'(lheFed~~taiEn.rgerq~n*lt~(FCMA). o--.us~a-.,.o....-e~c-....CIOC,NA-ac--~---= --(r.CIMl,N..,...DeoNII..._(NOI~OM!oW~IUCI.'""*-.......otl tiOct .... _,.~W'IMIQ-...._._..._rm.IUIO...,_ei~(USI)A). C:.W.""'~c:.-0<\--...,..............,•.,.~-*'--1~ ...._,_lSIU_>c __ 0.5 Kilomotors CrMitd by th<IPIC& lt'oUtu:.,o.J.Jand, Clldomil, 2000. Pfoj«:t funded by tnt C.Worftll EMI\IY ComrTUiootl'' PWiic ln\et1oll El'ltfQY R .... rctl Pfoort.tn. c.ITtMl. and ltle Clllbmia Ool¥\ PtO*OOn Co.H'd Gndooordin;~: .. ; UTM Zone 11N 1'1'11"1$ NADSJGCS~ts , ...... .,. ·--3: Tonn •. nolptfnt«J 5: Ugloi'UIBNdl 1: nolprlrted 1./IOfptfrJf«< •. nolprfrted PA2017-019