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Home My WebLink About15-01-14 Item 1 - Balboa Island Seawall Update - PPT UPDATE : Balboa Islands Seawall Rehabilitation Project rr i •� .F Harbor Commission January 14, 2015 Harbor Seawalls Ipp IL ;1M1* y��1 i * _ -17 m; ------------ I aimW W ecr OR. WATfRf'ROW FH[INTAGE M BEV, W WPW G® � � � • ,., _ � , .. tires ; . +' �'�.�, � r��__ 1F j,- yam.� r s .,,: r J K �, Li .. ...E �, A '�hj�1' a �'t� R T/ }fed^ � •� '�, ° ��. dim n r a- ,� rN.+°1�s`"`I.'��.., � .�1 by n t�.,m..t i Y7Y'4i^h�, `` � _ ��. ��,,,"`y��3cc Y _ �' .. y� C w E wi G ,,. ,.�� ,., �J� e t '1�', ,. Wit ,_; .. b`' .r �� t.N t 7, ,� / �_� _ .� ,..� •. _ .,.. .. •wry: - � �":-.mow-:-�aa'eRvnn" .� y * '. •�,M icy �. V-: �r 4 r}. 4ti`d, Zx+ k� .X. C 1, sem('�'� ,il .,,i^.;:. 1 Floating Sidewalk — West • of Balboa Island 'P.i.'r.�f.'�.�✓.{'�tip. t Wall Movement =- Corroded Tie 10'-3 1/2' SHEET PILE Rods ANDCCAP (TYP.) ET PILE 11:1 I E) 1' ANCHOR ROD (TYP.) I I nn A ii A I ' I Existing Seawall at !rOARDWITE)SIE) TIMBER ANCHOR PILE (TYP.) Balboa Island West End PLAN Constructed : pre-1935T (E) CONCRETE EL +8.0' NAVD88BOARDWALK EL +5.75' NAVDB8 Rock reinforcement EL +1.8' NAVD88 installed 198 5 (E) ROCK E) TIMBER ANCHOR PILE : Jft EXISTING MUOUNE - 10' E) CONCRETE SHEET PILE EL -1o.8' NAVD88 U SECTION A-A (ASSUMED) CASE 2-EXISTING CONDITION at WEST END - r d - Pie Crack (Close-up) w fig J J r' Grand Canal �' - Balboa Island : Grand Canal — North End , Al r a 1 Newport Marina VillasTownhomes Seawall Failure - Shallow Pile Embedment ,oo h Balboa Islands Seawalls 85 year old walls . ( Original lifespan approximately 75 years . ) Walls are exhibiting obvious signs of deterioration and stress . Existing walls subject to seismic risk. Grand Canal : Depth of wall below mudline is very shallow. Many unknowns : seawall rebar, sheetpile condition below mudline, tiebacks . Useful lifetime : 10-25 years (2011 report) Seawall Requirements Structurally-sound seawall system Islands protected from flooding C. Provide access to docks and beaches � 1 ,.,t., . December 2010 Storm .rt+i•.. ( � • =. ! ,ria. R.�..""��. - - }.' �' .s,J..e.. •i._ -+X3'c Ilaw I' Flooding Potential : 2025 - Highest 1% Tides with Wind Waves Scenario 07: Year 2025 / Tide p:=01% / Wind Waves 6069260 6069600 6069160 6060000 6060260 6060600 6060960 6061000 6061260 6061600 6061160 6062000 6062260 6062600 6062160 6063000 6063260 606.3600 s ORI It s � t 1 w' M � �J.l t:CJN2 613' - 4 8 e ~ Y N n i 5 C r MY Y u O &1Y Y 8 0.063 F 025 0 r 05-io 8 i0-2o 8 - - 6 20-ao G M 30-60 Modeling scenarios are based on VS Army Corps of a0-60 Engineers sea level rise estimation methodology and 0 250 500 1.000 1,500 2,000 60.80 are subject to change as new scientific data is obtained. Ft 4050250 405050 4069160 6060000 4040050 4060600 4040160 4061040 4061250 6061600 4061360 6062000 6062260 6062600 6062360 6063000 6063260 6063600 2025 : No Flooding with Sandbags Scenario 12 : Year 2025 / Tide p=01% / Wind Waves / Deployment of Sandbags 6069250 6069600 6069750 6060000 6060260 6060500 6060760 6061000 6061250 6061600 6061760 6062000 6062250 6062600 6062160 6063000 6063:50 60635oa a s moa zsla m oe i t f N . � s � 6� � -.l YSi_�i 11IpN y N _ Y iA'.Nl A p:,12 N � d 0 $ e M N A Ltit 6 0.025 6 025.0 G 05.10 $ 10-20 6 20.30 6 H 30-6 0 Modeling scenarios are based on US Army Corps of 60-60 Engineers sea level rise estimation methodology and 0 250 500 1,000 1,500 2,000 S 60-80 are skbject to change as new scientific data is obtainai. Ft 6659260 6059500 6069750 6060000 60"1" 6060500 6060760 6061000 6061250 6061600 6061760 6062000 6062260 6062500 6062750 6063000 6063260 6043600 Top of Seawall Elevation --------- ....... ----- ...... lopElevation Ffood Protecwtion (NAVD88) (Approximatsl.:%,'� 1 10.0' 2060 2 9.51 2055 3 9.5'(south)/9.0'(north) 2045 4 9.0' 2040 5 8.7' 2030-2035 New Seawall — Option 1 H - piles and Concrete Wall ( Lag) Panels ( No tiebacks) 4 - s A I t \ ri - 09/ 15/2014 Locations for New Seawall and Seawall Cap Extensions GRAND CANAL(GC) 41116 A NORTH EXPOSURE S r. SOUTH EXPOSURE LEGEND: GRAND CANAL 8 WEST END EXPOSURE,NEW SEAWALL(1,120'2) O SOUTH EXPOSURE.CAP EXTENSION(1,3355) _ NORTH EXPOSURE,CAP EXTENSION(2,750'*) �,••, m EAST EXPOSURE.NEW SEAWALL OR CAP EXTENSION(1,5663) Little Balboa Seawall Cap Extension ,tip r ..L y What about a Seawall Retrofit ? If the seawalls along the Grand Canal and West End are reinforced, can we expect another 20-25 years of service? Maybe . The success any retrofit is dependent upon the structural integrity of existing walls. The seawall will need to be tested first. Cost for core samples, lab tests & report : $ 150,000 to $200,000 (E) REINFORC Along Grand CONCRETE PANEL (IYP.) �I E) 1' ANCHOR CANTILEVERED 'HPILE i / ROD (TP.) Canal • (2 PER PANEL) cl I H - Pile CONCRETE d BOARDWALKS , I Supports (E) REINFORCED E) TIMBER along Grand CONCRETE SOLDIER ANCHOR PILE (T-11P.) PILE cTYPa PLnN CanalR RESIDENTIAL STEPS AND PIER tREINFORCED CAP EL +9.0' NAVOBB r----- DWALK L-TT -TT- CANTILEVERED 'H' PILL'(2 PER PANEL) PROPERTY LINE I ' E) TIMBER ORCED) ANCHOR PILE I )I )ORCEDEPILE SEgnON" Option 2 - Grand Canal Projected Costs Rehabilitation Option 1 . seful Lifetime All New Seawalls ( 10 feet) $70 million 100 years Raise walls after 2060 if needed New Seawalls along West End $32 million 100 years and Grand Canal + Capping 20-25 years then replace capped walls (> $45 million) New Seawall along West End + $22 million 100 years H-Pile support along Grand 20-25 years then Canal + replace with new Capping seawalls (>$55 million) Private Pier Access vl/' s from Newr ell- Seawalls - I u r�.ani�r•a±o p PO.LLVf Public Pier and Beach Access rw.»ro•'r.5� M L%v � � J F4D 4:,p�aro Beach Access i Concept r What about a tide gate at the jetty? I . Verify sea level rise predictions By about 2020, king tides could be 2-3 inches higher than today — on track for a 55" rise in sea level by 2100. 2. Set new harbor-wide standard for top of seawall elevation, e .g., 10 feet NAVD88 3. Set new requirements for finish floor elevations Other Items under Consideration Flooding at Ferry Landing Protection at Collins Island Protection from Rising Groundwater Raising Boardwalk Funding e °•�1 "' `� * SYS` !'�;„�' f ' �� ' • ,�, '� ,J+v • r � ElT 1N. (i a3a u t _4 11 h Areas 'a••wi e1��, �T � t�Q •' � x� ' v , .is 1WU I.• 1 feet ♦ .Y'i�.y. 'Precicted flood elevation based an a 55 inch sea level rise by 11 ?i (California State Coastal Conservancy adopted Climate Change Policy- 2009) Flood elevation is based on a high(1 1Y.)tide with 5-year storm I surge event Assume seawall heights are 9 feet(NAVD88) y Areas below elevation 12 feet at risk of periodic flooding by ~2094 if no protective measures taken. IR 1 wyk �� v'm "� !t->c:�• , ss ,t3 lie � ? } t. Areas prone to periodic flooding of streets and low lying areas.` - 2064-Maximum Flood elevation is 10 feet 2094-Maximum flood elevation is 12 feet 'Predicted flood elevation based on a 55 inch sea level rise by 2100 (California State Coastal Conservancy adopted Climate Change Policy- 2009).Flood elevation is based on a high(1%)tide with 5-year storm surge event.Assume seawall heights are 9 feet(NAVD88). Webpage and Community Comments City Web page: http://www. newportbeachca.gov/seawalls Comments and concerns: seawal Is(aD- newportbeachca.gov Staff contact: Bob Stein , 949-644-3322