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HomeMy WebLinkAboutPA2022-0196_20220817_Coastal Hazards Analysis ReportPMA CONSULTING, INC. CONSUL TING STRUCTURAL ENGINEERS 28161 Casitas Ct. PH. (714) 717-7542 Laguna Niguel, CA 92677 August 17, 2022 Ian Harrison 3535 East Coast Hwy #301 Corona Del Mar, CA 92625 e-mail: consulting@pma-bg.com RE: COASTAL HAZARDS ANALYSIS REPORT FOR COASTAL DEVELOPMENT PERMIT Linda and Larry Rodman; Applicant 550 South Bay Front City ofNewport Beach, County of Orange PMA Job #49822 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 7 5 years and addresses compliance with Coastal Hazards Analysis Report requirements and standards ofNBMC 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 of2000 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 PA2022-0196 governments to analyze and assess the risks associated with sea-level rise, and to incorporate Sea- Level Rise into their planning, pe1mitting, 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 2097 shall be approximately 3.05', 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. 75'NA VD88. 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. Table No. 2 Year Structure Adopted NB Standard Design for Adaptability Permitted Elevation (feet) 1 Elevation (feet) 2 NAVD88 MLLW NAVD88 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 J. Derived using the Upper Limit of the Low Risk Aversion probabilistic sea level rise protection scenario for the Los Angeles tidal gauge, estimated 75 years into the future 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 approximalely an 83 percent probability that sea level rise falls 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 75 years into the future based 011 the State of California Sea level Rise Guidance, 2018 Update. This scenario accounts for increased sea level with approximately a I-in-200 or 0.5 percent probability that sea level rise exceeds the elevations shown. Requirements in Appendix A for Step 2: Determine how physical impacts from sea level rise may constrain the proiect site, including erosion, structural and geologic stability, flooding, and inundation. According to the enclosed Precise Grading Plan Cl, 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 PA2022-0196 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 wa1ming 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' NA VD88, 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 2097. WAVERUNUP 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. <· / Limit of Wave Runup I .. ~ .. -:,~J'•""',...,.._, ~ ......... t . Stillwater Elevation Hypothetical Slope Wave Runup Sketch 3 PA2022-0196 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 ve1y 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'MLL W this shall result in slight ove1topping 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-te1m changes. According to the report, the average rate of long-te1m shoreline change for the State of California was 0.2±0.1 rn/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 rn/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 ofNewpo1t 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 NA VD88 (10 ft MLL W) which would place the new wall 0.8 feet above the current Base Flood Elevation of 9.0 feet NAVD88 (9.18 feet MLL W) -see 4 PA2022-0196 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, cunent 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 C 1 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 5 PA2022-0196 ...,_ __ -- PMA Consulting!) In~. Consulting Snu ctural Engineers 28161 Casitas Ct., Laguna Niguel, CA 92677 Phone: (714) 717-7542 E-'.\1ail: P.Petrov@P'.\'1.I\-BC.com 550 SOUTH BAY FRONT BALBOA ISLAND, CA 92662 No-rr1i !Jqy f ro(\\ sugar n Spice Balboa Island BA LBOA ISL1 ND ll ?' 550 s Bay Front, I!) Newport Beach, CA ... PROJECT TE -----------.. __ Bal boa P1 er·~---.__ ft unicipal lot T --~------ 11'.!::;I . d B1alooa PeninS_IJ~a Pa · a ri • • n • a r.i / --~,~ .... ___ _ ·--------Bal boa Pe"iiTnsu la Harbor Island Reach Racquet Clu Nancy Har~•ison ft & Associates T LOCATION MAP JOB. 49822 DES. PBP DATE 08/17 /22 PA2022-0196 PMA Consulting~ In~. Consulting Structural Engineers 28161 Casitas Ct., Laguna i\"iguel, CA 92677 Phone: (714) 717-7542 E-Mail: P.Pen-ov@PiVIA-BG.com 550 NORTH BAY FRONT BALBOA ISLAND, CA 92662 AERIAL VIEW JOB. 49822 SHT. DES. PBP DATE 08/17 /22 PA2022-0196 'iJl(fl l Qr I 1(¥>0 TOPOGRAPHIC SURVEY LOT 7 OF BLOCK IS, MAP OF RESUBOIVISION ONE. BALBOA JSL,\NO, MM. 6/30. -..:'•· .. ~--,..---····'<'---+-,-,-_1··-tt4-~c,:.7 '~-:-:.·!, ~.L-r \ ., ' ~: N"'C','1.UY►lt . /~~', ___ t~ _ l."LIYAl.ll'Y I U ~• -__ ,c __ '_ -~/----1-_,_· _, ______ ----~-·-~ ~ -,-~ •1<11 I.I t t'•• \ I ~ '-l)Jf ,·-·· ~-· _ _) • 5◄8 SQ..tH llo\f rf~Qlll l 'SU_.."f SfD fll!Al'l'. 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RODMAN RESIDENCE 550 SOUTH BAY FRONT 13:\L801\ ISLAND, CALIFORNIA 91662 ,i ----------------------------------------------- SOUTH BAY FRONT NEWPORT BA) PR[CIS[ GR.ADll'<G PLAN ■ I\NJ.N.H\RRJS..."1:S- ,\RCHITECT '~:;::~~·:::',' ~:,~·~::;::' -"•lN,7ll-ll>ll -11'"''-''''""'-~<,tomh,"'-' 9 PA2022-0196 High emissions 2030 2040 2050 low emissions 2060 High emissions 2060 low emissions 2070 High emissions 2070 low emissions 2080 High emissions 2080 low emissions 2090 High emissions 2090 low emissions 2100 High emissions 2100 l ow emissions 2110· High emissions 2110· low emissions 2120 High emissions mo low emissions mo High emissions mo low emissions 2140 High emissions 2140 low emissions mo High emissions 2150 STATE Of CA LIFORNIA SEA-LEVEL RISE GUI DANCE 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 7997 -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. Low Medium· High Extreme Risk Aversion Risk Aversion Risk Aversion 0.3 0.2 0.5 0.6 0 .7 1.0 0.5 0.4 0.7 0.9 1.2 1.7 0 .7 0.5 1.0 1.2 1.8 2.6 0.8 0.5 1.1 1.4 2.2 1.0 0.7 1.3 1.7 2.5 3.7 0.9 0.6 1.3 1.8 2.9 1.2 0.8 1.7 2.2 3.3 5.0 1.0 0.6 1.6 2.1 3.6 1.5 1.0 2.8 4.3 6.4 1.2 0.7 2.5 4.5 1.8 1.2 3.4 3.05' FOR 5.3 8.0 1.3 0.7 3.0 YEAR 2097 5.4 2.2 1.3 4.1 6.7 9.9 1.4 0 .9 3.1 6.0 2.3 1.6 3.3 4.3 7.1 11.5 1.5 0.9 2.5 3.6 7.1 2.7 1.8 3.8 5.0 8.3 13.8 1.7 0 .9 2.8 4.0 8.1 3.0 2.0 4.3 5.7 9.7 16.1 1.8 0.9 3.0 4.5 9.2 3.3 2.2 4.9 6.5 11.1 18.7 1.9 0.9 3.3 5.1 10.6 3.7 2.4 5.4 7.3 12.7 21.5 •Most of the available climate model experiments do not extend beyond 2700. The resulting reduction in model availability causes a small dip in projections between 2700 and 2770, as well as a shift in uncertainty estimates (see Kopp et al. 2074). Use of 2770 projections should be done with caution and with acknowledgement of increased uncertainty around these projections. APPEND IX l : SEA -LEVEL RISE PR OJECTIONS FOR All 11 TIDE GA UGES I 72 10 PA2022-0196 High emissions 2030 2040 2050 Low emissions 2060 High emissions 2060 low emissions 2070 High emissions 2070 low emissions 2080 High emissions 2080 low emissions 2090 High emissions 2090 Low emissions 2100 High emissions 2100 Low emissions mo· High emissions 2110' Low emissions 2120 High emissions 2120 Low emissions mo High emissions mo Low emissions 2140 High emissions 2140 Low emissions 2150 High emissions 2150 STAIE Of CALIFORNIA SEA-LEVEL RISE GUIDANCE 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 7997 -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. Low Medium· High Extreme Risk Aversion Risk Aversion Risk Aversion 0.3 0.2 0.5 0.6 0.7 1.0 0.5 0.4 0.7 0.9 1.2 1.7 0.7 0.5 1.0 1.2 1.8 2.6 0.8 0.5 1.1 1.4 2.2 1.0 0.7 1.3 1.7 2.5 3 .7 0.9 0 .6 1.3 1.8 2.9 1.2 0.8 1.7 2.2 3.3 5.0 1.0 0.6 1.6 2.1 3.6 1.5 1.0 2.2 2.8 4.3 6.4 1.2 0.7 1.8 2.5 4.5 1.8 1.2 2.7 3.4 5.3 8.0 1.3 0.7 2.1 3.0 5.4 2.2 1.3 3.2 4.1 C0) 9.9 1.4 0.9 2.2 3.1 6.0 2.3 1.6 3.3 4.3 7.1 11.5 1.5 0.9 2.5 3.6 7.1 2.7 1.8 3.8 5.0 8.3 13.8 1.7 0 .9 2.8 4.0 8 .1 3.0 2.0 4.3 5.7 9.7 16.1 1.8 0.9 3.0 4.5 9.2 3.3 2.2 4.9 6.5 11.1 18.7 1.9 0.9 3.3 5.1 10.6 3.7 2.4 5.4 7.3 12.7 21.5 •Most of the available climate model experiments do not extend beyond 2700. 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. 2074). Use of 2170 projections should be done with caution and with acknowledgement of increased uncertainty around these projections. APPEN DI X 3: SEA·LEVE L RISE PROJECTIONS FOR Al l 12 TIDE GAUGES I l2 11 PA2022-0196 9410580 NEWPORT BEACH, NEWPORT BAY ENTRANCE, CA Home(/) / Products (products.html) / Datums (stations.html?type=Datums) / 9410580 NEWPORT BEACH, NEWPORT BAY ENTRANCE, CA Favorite Stations T Station Info T Tides/Water Levels T Meteorological Obs. Phys. Oceanography Datums for 9410580, NEWPORT BEACH, NEWPORT BAY ENTRANCE CA NOTICE: All data values are relative to the MLLW. Elevations on Mean Lower Low Water Station: 9410580, NEWPORT BEACH, NEWPORT BAY ENTRANCE, CA Status: Accepted {Apr 17 2003) Units: Feet T.M.: 120 Epoch: {/datum_optlons.html#NTDE) 1983-2001 Datum: MLLW Datum MHHW (/datum_options.html#MHHW) MHW (/datum_options.html#MHW) MTL (/datum_options.html#MTL) MSL {/datum_options.html#MSL) DTL (/datum_options.html#DTL) MLW (/datum_options.html#MLW) MLLW (/datum_options.html#MLLW) NAVD88 (/datum_options.html) STND (/datum_options.html#STND) GT {/datum_options.html#GT) MN {/datum_options.html#MN) DHQ (/datum_options.html#DHQ) Value 5.41 4.68 2.80 2.78 2.71 0.92 0.00 0.18 -3.33 5.41 3.76 0.74 Description Mean Higher-High Water Mean High Water Mean Tide Level Mean Sea Level Mean Diurnal Tide Level Mean Low Water Mean Lower-Low Water North American Vertical Datum of 1988 Station Datum Great Diurnal Range Mean Range of Tide Mean Diurnal High Water Inequality 12 PA2022-0196 Daium DLQ (/datum_options.html#DLQ) HWI (/datum_options.html#HWI) LWI (/datum_options.html#LWI) Max Tide (/datum_options.html#MAXTIDE) Max Tide Date & Time (/datum_options.html#MAXTIDEDT) Min Tide (/datum_options.html#MINTIDE) Min Tide Date & Time (/datum_options.html#MINTIDEDT) HAT (/datum_options.html#HAT) HAT Date & Time LAT (/datum_options.html#LAT) LAT Date & Time Tidal Datum Analysis Periods 01/01/1980 -12/31/1993 Value 0.92 5.08 11.15 7.67 Description Mean Diurnal Low Water Inequality Greenwich High Water Interval (in hours) Greenwich Low Water Interval (in hours) Highest Observed Tide 01/28/1983 08:06 Highest Observed Tide Date & nme -2.35 Lowest Observed Tide 01/20/1988 16:30 Lowest Observed Tide Date & Time 7.18 Highest Astronomical Tide 12/02/1990 16:06 HAT Date and Time -1.92 Lowest Astronomical Tide 01/01/1987 00:00 LAT Date and Time To refer water level heights to NAVD88 (North American Vertical Datum of 1988), apply the values located at National Geodetic Survey (http://www.ngs.noaa.gov/Tidal_Elevation/diagram.jsp?PID=DX1968&EPOCH=1983-2001 ). 5 Datums for 9410580, NEWPORT BEACH, NEWPORT BAY ENTRAN All figures in feet relative to MLLW DHQ: 0.74 MHW: 4.68 •·---------l-- 13 PA2022-0196 BALBOA ISLAND TOP OF SEAWALL ELEV, RANGE LEGEND: 10 10 10 9.30'---9.48'---9.68' 9.00'---9.18'---9.38' 9 9 7.70'-_ 1.. 7.88'--8 8.08' 7 7 6 8 6 5 5 5 4 4 4 3 3 3 2 2 2 1 1 0 NAVD88 - - -0.18'-- -0.38' 0 MLLW NTDE 1983-2001 0 MLLW NTDE 1980-1978 NTDE 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) NAV088 ca NORTH AMERICAN VERTICAL DATUM 1988 BASE FLOOD ELEVATION (PER FEMA AS ADOPTED BY NEWPORT BEACH IN DEC, 2009) (GEODETIC VERTICAL DATUM USING A SINGLE FIXED REFERENCE POINT) Figure 2.1 Comparison of Different Tidal Datums 14 PA2022-0196 INTERIOR--~ FINISH P.T. SILL-- PLATE T.O.S.-- I • ' . ' EXTERIOR FINISH PER PLANS ~--PLYWOOD SHTG ~--BITUTHENE (OR EQUIV.) 23" ABOVE T.O.S. (CONTINUOUS 31 ") ----COPPER/S.S. WEEP SCREED SLOPE 1 % MIN • ~ • • ., 4 ' ' . ·SLOPE 2% MIN • T.O.S. ELEV= +9.OO'NAVD88 LINE OF FINISH SURFACE LINE OF FINISH GRADE CONCRETE SLAB OR 1/J "o 0 (}) I- i-' ci g; 15 W LL Q:'. >O@O 0 I-0 rn _J <( 0 · LL z> +I w ::'.J ' I-w nX NW PAVED AREA (AS OCCURS) CONC FTG '------COPPER FLASHING OVER & SLAB BITUTHENE (OR EQUIV.) 8" BELOW & 6" ABOVE T.O.S. (CONTINUOUS 14" MIN) FLASHING & WATERPROOFING DETAIL I NTS PA2022-0196 ~ PACll'IC I NSTITUTE California Flood Risk: Sea Level Rise Newport Beach OE S Quadrangle • -uSK?'-", 0 -so. .... ~ .. 0 -1:<v'<)'~ .. □ o.,,.,.c-,.,Ba,oflood 1_,..,,_"""4,_,.J s.,1._1t,o5oo_,, Co.o""I .... Flood•U..-.(MC..,_I ........... 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