Loading...
HomeMy WebLinkAboutPA2021-268_20211108_Coastal Hazards Analysis_10-29-21 P M A C O N S U L T I N G , I N C . CONSULTING STRUCTURAL ENGINEERS 28161 Casitas Ct. PH. (714) 717-7542 Laguna Niguel, CA 92677 e-mail: consulting@pma-bg.com October 29, 2021 Ian Harrison 3535 East Coast Hwy #301 Corona Del Mar, CA 92625 RE: COASTAL HAZARDS ANALYSIS REPORT FOR COASTAL DEVELOPMENT PERMIT Gary and Dottie Gunderson; Applicant 139 North Bay Front City of Newport Beach, County of Orange PMA Job #43521 Dear Mr. Harrison, PMA Consulting, Inc. 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 standards of NBMC Section 21.30.15.E.2. STATEMENT OF THE PREPARER’S QUALIFICATIONS Plamen Petrov, P.E., the preparer of the Coastal Hazards Analysis Report on this project, holds a Master of Science in Structural Engineering from University of Architecture, Structural Engineering & Geodesy of Sofia, Bulgaria, and is a Licensed Civil Engineer by the State of California Certificate No. C66947. Since Year of 2000 he has been actively involved in the design and entitlement of many Waterfront Developments such as custom homes, seawalls, piers, platforms, floating docks and marinas. A great number of Coastal Hazards Analysis Reports prepared by him have been reviewed and accepted/approved by California Coastal Commission. All the above being said, Plamen Petrov, P.E. shall be considered a qualified preparer for the Coastal Hazards 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 California Energy Commission provides a bold, science-based methodology for state and local 1PA2021-268 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 High emissions 2090 & 2100 and Low Risk Aversion, over the project’s planning horizon of 75 years, the estimated Sea-Level Rise (SLR) for year 2096 shall be approximately 3.00’, which is the Sea- Level Rise for the proposed project. 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 +10.70’NAVD88. As of March 23, 2021, City Council of City of Newport Beach has adopted new standards establishing a minimum top of bulkhead/seawall elevation based on 5-year increments, reflected in Table 2 below from City of Newport Beach Waterfront Projects Guidelines and Standards Harbor Design Criteria for Commercial and Residential Facilities 2021 Edition. 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 Precise Grading Plan C1, top of slab at 1st floor of the proposed development is at +9.00’ NAVD88=+9.20’MLLW which follows 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 until year of 2063, based on Low Risk Aversion. 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. 2 Table No. 2 Year Structure Adopted NB Standard Design for Adaptability Permitted Elevation (feet) 1 Elevation (feet) 2 NAVD88 MLLW NAV088 MLLW 2020 10.7 10.9 13.7 13.9 2021 -2025 10.9 11.1 14.4 14.6 2026-2030 11.0 11.1 14.6 14.8 2031 -2035 11.0 11.2 14.8 15.0 1. Derived using the Upper Limit of the Low Risk Aversion probabilistic sea lei el rise proteclion scenario for the Los Angeles tidal gauge, estimated 7 5 years into the ji,ture based on the State of California Sea Level Rise Guidance. 2018 Update. This scenario accounts for the upper range of what is "likely to occur" ·with approximately an 83 percent probability that sea level rise fi1lls below the elevations shown. 2. Derived using the Medium-High Risk Aversion probabilistic sea level rise protection scenario for the Los Angeles tidal gauge, estimated 7 5 years into thefuture based on the State of California Sea Level Rise Guidance, 2018 Update. This scenario accounts for increased sea level with approximately a l -in-200 or 0.5 percent probability that sea level rise exceeds the elevations shown. PA2021-268 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. According to the enclosed Topographic Survey, top of Existing Seawall/Bulkhead in front of the subject site is at an elevation of +8.62’NAVD88 (North American Vertical Datum of 1988). 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 Sea-Level Rise generally fall in the range of 4.1-6.7 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 slab elevation of the proposed house will be at +9.00’ NAVD88, it will remain above the High Tide approximately until year of 2063. Utilizing Flashings and Waterproofing for up to 23” above top of slab, as reflected on the enclosed detail, and sandbags at openings shall keep the building protected from flooding until year of 2096. 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. 3 Stillwater Elevation Hypothetical Slope Wave Runup Sketch PA2021-268 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 runup 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 1.3 feet traveling within the bay. At the highest anticipated tide in Newport Beach of +7.88’MLLW this shall result in slight overtopping of the bulkhead/seawall. 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 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 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. CONCLUSION & RECOMMENDATIONS: In conclusion, flooding and wave runup will not significantly impact this property over the proposed life of the development if the existing bulkhead/seawall remains in its current condition. The subject bulkhead/seawall was built by the City of Newport Beach circa 1929. Thus, it is near its expected useful lifespan of 75 years. The bulkhead/seawall shows signs of distress and over the next 25 years will most likely exhibit advanced deterioration. Therefore, the City has hired Everest International Consultants, Inc. to assess the bulkhead at the entire Balboa Island and provide recommendations for its repair or replacement. The recommendations are as follows: 1. Begin replacement of the existing seawall within 10 years from baseline 2010 per Enclosed Figures 5.2, 5.3 & 5.5. This initial stage will consist of a perimeter seawall constructed to 9.8 feet NAVD88 (10 ft MLLW) which would place the new wall 0.8 feet above the current Base Flood Elevation of 9.0 feet NAVD88 (9.18 feet MLLW) - see 4PA2021-268 enclosed Comparison of Different Tidal Datums Graph. In the interim, augment the existing seawalls by 6 to 8 inches either by adding a cap extension, or by being prepared to deploy sandbags around the Balboa Island. 2. When necessary, extend the seawall by an additional 3 to 4 feet during lifetime of spanning Years 2050 and 2060 (i.e., 40 to 50 years from baseline Years 2010). 3. When necessary, construct a deep well groundwater dewatering system to protect the Balboa Island from subsequent high-water tables associated with highest extreme water levels. If see levels rise as predicted, this would need to be done during a lifetime spanning years 2050 and 2060. Once the existing bulkhead is replaced in compliance with the enclosed Figures 5.2, 5.3 & 5.5, no additional protective device will be required during the economic life of the associated structure, to protect it from flooding, wave runup or erosion. The conclusion & recommendations of this report were 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. Recommendations could change upon better certainty of the projected sea level rise. We make no further warranty, either expressed or implied. PMA Consulting, Inc. appreciates the opportunity to work with you towards the successful completion of your project. Should you have any questions regarding this report, please contact us. Respectfully submitted, Plamen Petrov, P.E. Principal Enclosures: Location Map Aerial View Topographic Survey Precise Grading Plan C1 Table 28: Projected Sea-Level Rise (in feet) for Los Angeles – Low Risk Table 28: Projected Sea-Level Rise (in feet) for Los Angeles – Low & Medium High Risk Datums for Newport Bay Entrance Comparison of Different Tidal Datums Flashing & Waterproofing Detail Newport Beach OE S Quadrangle Figures 5.2, 5.3 & 5.5 5PA2021-268 6PMA Consulting~ In~. Consulting Structural Engineers 28161 Casitas Ct., Laguna Niguel, CA 92677 Phone: (714) 717-7542 E-Mail: P.Petrov@PMA-BG.com PROJECT SITE s u.; ~ CD </) 139 NORTH BAY FRONT BALBOA ISLAND, CA 92662 ach ... h B y r t LOCATION MAP JOB. 43521 SHT. DES. PBP DATE 10/29/21 B Ibo I I n PA2021-268 7PMA Consulting~ In~. Consulting Structural Engineers 28161 Casitas Ct., Laguna Niguel, CA 92677 Phone: (714) 717-7542 E-Mail: P.Petrov@PMA-BG.com 139 NORTH BAY FRONT BALBOA ISLAND, CA 92662 AERIAL VIEW JOB. 43521 SHT. DES. PBP DATE 10/29/21 PA2021-268 8 c_:=-_.=-:=-_:; EXlSTl"6 WCIETE -(6) ~EXISTJA6 WITlUl r7_z-L:J...:r--D£XfSTl"6HA~YNALL ----PffPERTYLOE EXlSTl"6 NIXlJ F£ICE l CENTEILI/'£ -WCENTRATEO SUFACE Fl.OK SET LEAD & TACX TA6GEJJ PLS 7921 r.NPFlFERTYLDE ~ 4· n:o, fXR£R ) //// ~ ~: ~ ;:L~ /////////////////////// ~ ~-~~-----------~ N l EXISTING HOME SCAL£•J"=JO' I MJ(I) STEPS ....J.~111 11 I [I EXISTING HOME ,----I iii I : : I : :~1 EXISTIMJ /OE 1~1 I I i [~I 1ii I " ' ~ I I [[I m=o [,_"'I""'"~~.'.::. / t ______________ J T--1. I UTILITY GAR.. ~J-\ , -.,r-~'v I _____ m,occm_'.:;·76..'roJ'/ "u" __ /o,a;FFJ __ [ -;;,cs/ (<,~/ ~-\ --;;,;:;;;,,,, cWW' :;;;, , mO!<CI f-1-1 ~ ~,5'-~~=""'""'---:.-• --~JL_-~---q,--, 6,~-+--~-'-i:."'~-~\-m.iiRi ALLEY .::i/ , . . . r5.9[£C) fl\ , m.,;rr1 . Ill ' ·,. •·.. '• . 7" ,., mzm j = .,, <;// A) (D(TRN;TlR SH4LL W{TACT lNEIBUNJ SERVR:E ALERT. 1~133. 48 l6RS 1N AOVMa" tF ClNEJCEJENT" tF w.tSTFU:TICI( RR EXIST.Dli Vlll.ITY La:ATRNi. Preps'ed Ftr: o~/ ~&i: BJ 800/ IWI<: O.C. a»nY BOOI N411( # 1'8-15-70 El.EVATDI • 7.986 Gary &nderson 1626/ 354-9229 gary=yahoo.com BLEDSOE GIRON 3-3/4" «:S ALlNDUt 800/ N4II( DIS< STAJFEU 163-15-70; SET IN T1£ EASTER.Y BO tF A a:,,cJV'E SEA 11"-i.. IOUENT JS LOCATED 1N T1£ SWTHEST ctRER tF T1£ 1NTERSEC1'](J,I (F PAR< Alf7oU' ,WJ SO/TH 84Y ffOIT, J5 FT. sam£R. Y (F T1£ C£N1ER.JJE (F P,441;' Alf7,U' ,WJ 6 FT. IESTER..YtFl£IES"TRIANll'ALKll!4Y. IOUENT JSSETL81:Z. IIITH 11E TIPFO 11£.sE"A IIALJ.. CJI.E&4!. CESrRJPTJ(H 11EEASTER.Y J5FEET'(FUJT JQAIO 11EIESTER.YJ5FEET'CFLOT JJ. JNFl.(0(2 (F 11E ISUJOIV/SDI (F SECTDI 1 (F 84!.«W m..4-\Q 1N 11E ClT'Y (F IEltP(RT 8EAC1i AS PER NAP IR'tRElJ IN lUX 6; PAS£ .JJ tF NISIB.LAJEIL5 M4P.5 l£aRJS tF a:w.G£ tDHTY. ENGThEERING & SURVEYING INC. 654 S. Gletdra A1-8'1.e Gletdra CA 91740 (626JE5-8ne infclflbledsoegitm.crn Amy L. Bledsoe PLS7921 Date TOf'OGRAf'HYSIJ~//EY 139 N. lJ,1/YFront. ~lJe8cl, Scale:ASSt»I lnrl&i:o\LB 1~ S-eet:101'1Sats~ PA2021-268 9" ? Fl vi m Cl s;: 0 z Cl " r > L. Ji " ii () ....Ji. z 8 ~I .,;1 ? ~ I I N DO°OO'OO' Vi 90.00' +---------Uo ~~ ~ !! ~~ r 8~ z UC'I I I I I ~ 'fl' !" . p~1~w1 Ii l • II ~ ~ n,•2 ~1l JI~;~. I Ii ii'! !. • !h I!! • • i • . ii;u 1;1U mi ~tij0 r~ J§e ~-1, I """"''OT~ ....... +--------------+-----+ NOR. TI-I BAY FR.ONT NEWPORT BAY >-+-+-+-+[>'--< a ~ a ~ ~ i ~ GUNDERSON RESIDENCE ~ ; ~ >-+-+-+-+'--<~ ;'; ~ 139 NOR.TH BAY FR.ONT ~ i l ! BALBOA ISLAND, CALIFORNIA 92662 PRECISE GRADING PLAN 11 IAN J.N. HAR.RJSON MCHITECr 220NEWPOR.TCENIERDIUVE,SlHfEl-}12 NEWPORTBE,\CllG\llFORNIJ\<r.!660 --(949)723·1091 -v.NWIA),,;IIAA.JUSOSAAOIIITCT.coM PA2021-268 Probabilistic Projections (in feet) (based on Kopp et al. 2014) H++ scenario (Sweet et al. 2017) *Single scenario 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… 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 STATE OF CALIFORNIA SEA-LEVEL RISE GUIDANCE APPENDIX 3: SEA-LEVEL RISE PROJECTIONS FOR ALL 12 TIDE GAUGES | 72 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. *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. 10PA2021-268 Probabilistic Projections (in feet) (based on Kopp et al. 2014) H++ scenario (Sweet et al. 2017) *Single scenario 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… 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 STATE OF CALIFORNIA SEA-LEVEL RISE GUIDANCE APPENDIX 3: SEA-LEVEL RISE PROJECTIONS FOR ALL 12 TIDE GAUGES | 72 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. *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. 11PA2021-268 12PA2021-268 13 DHQ: ♦-------+-­MHW: 4.68 PA2021-268 Seawall Assessment for Balboa Island and Little Balboa Island Main Report Everest International Consultants, Inc. 2.3 Figure 2.1 Comparison of Different Tidal Datums 14 BALBOA ISLANOTOP OF SEAWALL ELEV, RANGE LEGEND: 10 6 5 4 3 2 10 9.30'-- - 9.00'- - - 9 7.70'--.!_ 7 6 5 4 3 2 10 9.48'- - - 9 7.88'- -8 7 6 5 4 3 2 9.68' BASE FLOOD ELEVATION 9.38' ~~•-~-------- (PER FEMA AS ADOPTED BY NEWPORT BEACH IN DEC. 2009) 0 NAVO88 - - -0.18'- - -0.38' 0 MLLW NTOE 0 1983-2001 MLLW NTOE 1960-1978 NTOE NATIONAL TIDAL DATUM EPOCH (A 19 YEAR PERIOD OVER WHICH TIDAL DATA IS COLLECTED AND REDUCED TO OBTAIN MEAN (AVERAGE) VALUES FOR TIDAL DATUMS) MLLW MEAN LOWER LOW WATER {RELATIVE DATUM BASED ON NTDE DATA) NAVD88 = NORTH AMERICAN VERTICAL DATUM 1988 (GEODETIC VERTICAL DATUM USING A SINGLE FIXED REFERENCE POINT) PA2021-268 15INTERIOR ----II FINISH P.T. SILL-~ PLATE T.O.S. CONC FTG & SLAB EXTERIOR FINISH PER PLANS ~--PLYWOOD SHTG ~--BITUTHENE (OR EQUIV.) 23" ABOVE T.O.S. (CONTINUOUS 31 ") ~---COPPER/S.S. WEEP SCREED T.O.S. ELEV= +9.OO'NAVD88 LINE OF FINISH ,i_ -s -"" _. 1 SURFACE ·~ <l .• "" <1 -<Q 4 <l <1 ,j, 4 LOPE 2% MIN. LINE OF FINISH GRADE CONCRETE SLAB OR U) -.o 0 0) I-~ ~ ~ W LL Cl:'.'. >O@O 0 I-0 [I] _J <(0 ·LL z> +I w :=J ~ I-w nX NW PAVED AREA (AS OCCURS) ~----COPPER FLASHING OVER BITUTHENE (OR EQUIV.) 8" BELOW & 6" ABOVE T.O.S. (CONTINUOUS 14" MIN) FLASHING & WATERPROOFING DETAIL N.T.S. PA2021-268 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 419000mE3707000mN37 07000mN08 08 09 09 3710 3710 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 3720 37203721000mN3721000mN This information is being made available for informational purposes only. Users of this informationagree 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 16 PACIFIC INSTITUTE PA2021-268 Seawall Assessment for Balboa Island and Little Balboa Island Main Report Everest International Consultants, Inc. 5.4Figure 5.2 Conceptual Seawall Replacement Implementation Plan 17 --~$._ T.O.Sl.AB PUBLIC $1DEWAIJI & STRUT // i;IO:rnm. A'nttJCnliltl!. Existing Sample Condition (Baseline -201 0) New Seawall (Within 10 Years) r.L 1,,n T.o"'wiw:' iL 10.C& MLLW /0 f.6.SEAWAil Ir.Lib.A -~'"'~7,7:; ~L l_l, . /1l'///// , ./,LU,/,.'½ "'~~ff/§~ ~ w'o;i,..·r:.:,. '/WH. A" 1-~ffif--fl■'/~~.m <,3[@.· 'I . , '. d '*,%%~~1 1/};{r• ·?i@1f:,a./. ,K .. / :::-. r:~on:;,<·'.,' "·<f},b,~i~ / .. ':· .}1·:,. " ,f.l' "-'0W/2 .f½ #, ~/f ?f~,tf•···•°/,1_'.,,.,.~. 0£'1f'M£.RIH~ '%',~(f:;?' W£ll wr7~, ... ,... WATER fASLi l.t•. ,· n1ti:iwnnWN w CURVE ' GROUND WATER DEWATERING SYSTEM EL "•9:. 11).'NAU-\ llMT:ll.))" \\ (7100/ \ \ £L IO_l.t MU.W \_ TO ~,A,VA.I '-.. I // / i.V~1JH(;. krttUCffJllt, Seawall Extension (Est. 2050 -2060, or as req'd} LklikNJ. MHT Ylt ~Oli~ MAXAIUII HIGH TlDE PER FLOW tlMULATION. UC RiPORTOF mrro Yll.'trn'tM)l.E f. AU CU:VADONS SIIOWIY ARC. NA~ DAnJ.W UNL!" 01HEJtWUEN01E.D !!>EH)g.1~ 2. WJl.lER lJl.l!LEl'lffill:, Jl.~Ul~EnJl.l '1 ~'-':( "iUJW ,,oli l.;li,,11.L PA2021-268 Seawall Assessment for Balboa Island and Little Balboa Island Main Report Everest International Consultants, Inc. 5.5Figure 5.3 New “H” Pile System Seawall Retrofit and Extension 18 GIP SYSTEM (IIOHHOWH!-----..-----7 -~----,----~ CAP (NOT SHOWN FULLV FORClARfTY) NEW STEEL -H -PILE6 (TYP) NEW GROUT~ , NEW PR.ECAST ~ ~~::r;..P) ----------NOTE. CONTRACTOR TO PROVIDE CAPS I ARCHITECTIJRAL FINISH FOW EMl:JEOOEO SLEEVE & SHEAR KEY f\lTURE CAP EXTENSION C/PSYSTEM (IIOTSHOWHI-C::.. 7_ '" PER FLOW SIMULATION, LLC JUNE 1i, 2010 GIVEN AS NAVDU DATUM, . --EXISTING SLURRY I GROUT ~EM.ER '-;;,-~:~~G CONCRETE PROPERfY LINE E7JSTINO CONCKcfE SOLDIER PILES E)CI.STING TIE RO[)S EXI.STINC TIMBER PILE DEA.OMEN PVC SLEEVE ~------jf--CORRUGATED SLEEVES (INSn. 1> AS l"AAT OF• 10.0 CAP 1:XTENSJONI -----1-SET OF STIJOS PER PAIR Of' 5IICCT PIL.[:S ~EXISTING TIE RODS EXISTING TIMBER Plt.E DEADM.EN EL0.5 PROPERTY LINE ----~~ .--EXISTINC CONCRETE SOI.DIER PILES ---Option 1 -Case 1 New "H" Pile System Seawall Retrofit & Extension C1P SYSTEM (NOT SHOWN) -~-1.--------t-,-__ CAP (NOT SHOWN FULLY NEWSTEE.L -H -PILE5 (TYP) NEW CROUT NEWPRECAST CONCRETE PLAAKS (TYP) ---------NOTE: CONTRACTOR 10 PROVIDE CAPS & ARCHITECTIJRAL FINISfot FOf.l EMl:JEOOEO SLEEVE &SHEAR KEY FUTURE CAP EXTENSION YEAR 20SO {Ml PRE.STRESSED REINFORCED CONCRETE PLANKS --------NA.V0i8: ■ 0.0 ~LW!oj~ CIP SYSTEM (tfOT~HOwtO~ NEW STEEL• H • PILES 111 PER FLOW SIMULATION, LLC JUNE 11, 2010 Gl~N ~ NAVD8i DATUM. 7-FORClARrTY) EJUSTING SLURRY GROUT ~EALER EXJSTINC CONCRETE SHEETg PHOP£RTY Liff~ 0J3TING CONCfeflE SOLDIER PILES EXISTING TIE RODS EXISTING TIMBER PILE 0eAOMEN PVC SLEEVE ~--f--CORRUGATEOSLEEVES (INSn "OAS PART Of' • 10.0 CAP !.XTl:NStON) ..-------1·SET OF STUDS PER PAIR Of" SHEIIT PILCS EL6..7_ ~EXISTING TIE RODS ~fTl EXISTING TIMBER PILE ~ DEAOMEN EL0.5 PROPERTY LINE -' ----~J;J. -EXISTINC COIICRETE SOLOIE.R PILES ---Option 1-Case 2 New "H" Pile System Seawall Retrofit & Extension ~I LE.CEN.D: MHT MLLW NAV083 CIP TTP NOTES: E\. ... 14.Cn fL ♦10.0:t MLLW @ ® © CAP EXTENSION STYLES M.UIMUM HIGH TIDE PER FLOW .SIMULATION, llC REPORT OF "7110 MEAN LOWER LOW WATER. 1Hl.2001 DATUM NORTH AME.RICAN VERTICAL DATUM lffl (NAVOU "' 0.18' MLLW) CORROStoff PROTECTION TYPICAL 1. ALL ELEVATIONS SHOWN AME NAYOU DATUM UNL.ES'Si OTHERWISE HOTED C,EEfi~.1). PA2021-268 Seawall Assessment for Balboa Island and Little Balboa Island Main Report Everest International Consultants, Inc. 5.7Figure 5.5 New Steel Sheet Pile System Seawall Retrofit and Extension 19 NEW SLURRY GROUT NEW CIPSYSTEM tNOT SHOWN) -----= l"f" NOTE: CONTRACTOR TO PROVIDE CAPS & ARCHITECTURAL FINISH FOR EMBEDOE.0 SLE.EVE & SHEAR KEY R~:r.o·tor,,-EXJSTING SLURRY GROUT SEALER CAP (NOT SHOWN FULLY FOR CLARITYI EX.ISTING CONCRETE SHEETS PROPERTY LINE EX.ISTING CONCRETE SOLDIER PILES EXISTING TIE ROOS EXISTING TIMBER PILE DEA.OMEN ...,------r---PVC SLEEVE f-t .......... .,.-;;,/",,-----t--CORRUGATEOSL.EEVES (lN.STL"O AS PART OF •10.0 CAP EXTENSION) -1 1-SETOFSTUDSPERPAIR -~~··••1-0•1••·· ''---+---b!t~!1 ~ OFSHEETPIL.ES M._L.,L~l!·P-1;~ ll)PER FLOW SIMULATION, LLC JUNE 18, 2010 GIVEN AS NAVOBB DATUM, I•,~ I' :~" ~0.5 Option 2-Case 1 New Steel Sheet Pile System Seawall Retrofit & Extension 0,iSTING 111: RODS EXlSTING TIMBER PILE OEAOMEN PROPERTY LINE EXISTING CONCRE"TE SOLDIER PILES "' NEW SLURRY GROUT NEW CIP SYSTEM EXISTING SLURRY GROUT SEALER CAP (NOT SHOWN FULLY FOR CLARITY! EXISTING CONCRETE SHEETS PROPERTY UNE EXISTING CONCA£1'E SOLDIER PILES tNOT SHOWN) -----= l'>sf'1 EXISTING TIE RODS EJ(ISTING TIMBER PILE DEADMEN NOTE: CONTRACTOR TO PROVIDE CAPS & ARCHtTEC1URAL FINISH FOR l;Ml:I.C.DOE.O SLEEVE & SHEAR KEY FUTURE CAP UTENSION YEAR 2100 ~ 12.31°111 YEAR 2050 (MHll 9.09' 111 NEW CORRUGATED STl;EL SHEET PILES + CfP SYSTEM jNOTSHOWN)-<.___ PER FLOW SIMULATION, LLC JUNE 1115, 2010 GI\IEN AS NAVDH OATUM .....------t--PVC SLEEVE ._._ , ... ,..,.. -7',,-----t--CORRUGATED SLEEVES ONSTL'D AS PART OF •10,0 CAP EXTENSIONj ~ 1-SET OF STUDS PER PAJR • OF SHE:ET PILES Option 2-Case 2 EXISTING TIE RODS EXISTING TIMBER PILE OEAOMfN PROPERTY LINE EXISTING CONCRETE SOLDIER PILES New Steel Sheet Pile System Seawall Retrofit & Extension ~; MHT MLLW NAVD88 Cl!' TYP NOTES: EL •10.(n MLLY'li @ @ © CAP EXTENSION STYLES MAXIMUM HIGH TIDE PER FLOW SIMULATION, LLC RE.PORT OF 417110 MEAN LOWER LOW WATER. 198·:J-2001 DATUM NORTH AMERICAN VERTICAL DATUM 1988 (NAV0&8 • o.1a· M.LLW) COR.ROSION PROTECTION TYPICAL 1. All ELEVATIONS SHOWN ARE NAVO88 DATUM UNLESS OTHERWISE NOTED 1s ee Flo., 1. PA2021-268