Poe, Steven J.

English

Old Dominion University

Old Dominion UniversityODU Digital CommonsFebruary 22, 2019: Systems Approaches forResilient InfrastructureHampton Roads Sea Level Rise/FloodingAdaptation Forum2-22-2019Pivoting to the Future: Resiliency Planning inVirginia BeachSteven J. PoeFollow this and additional works at: https://digitalcommons.odu.edu/hraforum_23Pivoting to the Future:  Resiliency Planning in Virginia BeachHampton Roads Sea Level Rise/Flooding Adaptation ForumFebruary 22, 2019Steven J. Poe, PE, City of Virginia BeachStormwater Engineering Center1Agenda• Project Overview• Hazards and Risk • Adaptation Strategy Approach • Policy Document Overview• City-wide Structural Alternatives• Next Steps2Project Overview3Ongoing Studies• Comprehensive Sea Level Rise and Recurrent Flooding Study• Assessing existing and future flood vulnerabilities across the City’s four unique watersheds • Identifying strategies to ensure our city is resilient to future flooding events• Master Drainage Study• Detailed inventory of the City’s stormwater system• Assessing the system’s performance • Identifying deficiencies or needed improvements4Project Website: http://www.vbgov.com/pwSLRStudy Approach5Timeline of Activities2015 2016 2017 2018 20196Planning• Scenarios• Conceptual modelStudy Progression• Grant award• Hazard and risk assessment• Essential analysis to inform design• Stormwatercoordination• Policy menuStrategy Focus• Structural Alternatives• City-wide Concepts• Performance• Down-selection• Policy refinement and rankingsSynthesis• Neighborhood and site alternatives• Full Draft Adaptation Plan• Stakeholder outreach and inputHazards and Risk7VB SLR Planning Scenarios8Observed Acceleration9Boon et al. 2018~1.6 ftImpacts10Consequences of Future Without Action114x increase 23x increase$12 $50 $271 $0$50$100$150$200$250$300Baseline Scenario 1.5 ft SLR Scenario 3 ft SLR ScenarioAnnualized Losses (Millions)Compared to Today: Focus Areas for Adaptation1288% of City’s RiskAdaptation Strategies13Adaptation Strategies14Policy Design ProtectionIntegrated SolutionPolicy Document Overview15Policy Process16Policy Document17•What it represents: • Guidelines for instilling best practices to reduce long-term flood risk• Starting place for evaluation and implementation by City• Unique reflection of City staff perspective and priorities • Policy goals set up to match City Council goals*• Not a prescriptive document to be followed “to the letter”*A Strategic Plan to Achieve City Council's Vision for the Future and 2017 - 2022 City Council GoalsImplementation Vision• Administered and monitored by the Deputy City Manager SLR Working Group• Responsibility will be assigned for action items to City departments/staff• City staff will interpret and evaluate the action items and implement the action in general reflection of priorities• Implementation will occur after public comment18Informing Design19• Rainfall/surge correlation• >50% of rainfall events occur during elevated water levels• Joint-probability of rainfall/storm surge• Concurrent rainfall/surge design values• Regional Precipitation Trends• Atlas 14 outdated• Heavy rainfall increasing, 20% needed over design life cycle• Probable maximum event precipitation• Design “check storm” • Wind Tides • Water level response to wind tide conditions• Minimum design tailwatersInforming Design20Stormwater Design Standard Outputs21Existing Condition 3.1 3.6 4.0 4.4 5.2 5.8 6.2 6.7 8.51.5 ft SLR 4.6 5.1 5.5 5.9 6.7 7.3 7.7 8.2 10.03.0 ft SLR 6.3 6.9 7.3 7.7 8.5 9.2 9.6 10.1 12.0Existing Condition 3.2 3.9 4.3 4.8 5.5 6.3 6.9 7.4 9.31.5 ft SLR 4.7 5.4 5.8 6.3 7.0 7.8 8.4 8.9 10.83.0 ft SLR 6.4 7.2 7.6 8.1 8.8 9.7 10.3 10.8 12.8Existing Condition 3.2 3.8 4.1 4.5 5.2 5.9 6.5 7.1 8.51.5 ft SLR 4.7 5.3 5.6 6.0 6.7 7.4 8.0 8.6 10.03.0 ft SLR 6.4 7.1 7.4 7.8 8.5 9.3 9.9 10.5 12.0Existing Condition 3.6 4.1 4.5 4.9 5.4 6.3 6.8 7.3 8.71.5 ft SLR 5.1 5.6 6.0 6.4 6.9 7.8 8.3 8.8 10.23.0 ft SLR 7.2 7.7 8.2 8.6 9.2 10.1 10.7 11.2 12.8Existing Condition - - - - 2.4 3.4 4.2 4.9 6.41.5 ft SLR - - - - 3.9 4.9 5.7 6.4 7.93.0 ft SLR - - - - 7.6 9.0 10.1 11.1 13.2Existing Condition - - - - - 2.4 2.8 3.3 4.21.5 ft SLR - - - - - 3.9 4.3 4.8 5.73.0 ft SLR - - - - - 7.6 8.1 8.8 10.1Existing Condition - - - - - 2.8 3.4 3.9 4.91.5 ft SLR - - - - - 4.3 4.9 5.4 6.43.0 ft SLR - - - - - 6.3 6.9 7.5 8.5Existing Condition 2.8 3.6 4.1 4.7 5.8 6.5 7.1 7.9 10.31.5 ft SLR 4.3 5.1 5.6 6.2 7.3 8.0 8.6 9.4 11.83.0 ft SLR 5.9 6.7 7.2 7.8 8.9 9.6 10.2 11.0 13.42. Lynnhaven, Elizabeth River, and Atlantic Ocean elevations were sourced from the 2015 FEMA Flood Insurance Study 3. Back Bay and North Landing River elevations were sourced from CIP 7-030, PWCN-15-0014, WO2A4. The values do not represent potential wind-driven water levels in the Back Bay and North Landing River5. Back Bay and North Landing River tailwater values have been limited to return periods where tailwater elevations are above recurring wind tides.6. Conditions related to a 3-ft rise in sea level include non-linear increases derived from numerical modeling completed by the U.S. Army Corps of Engineers and the North Carolina Floodplain Mapping Program1. All elevations sourced from direct sampling and statistical analysis of the distribution of water elevations in each watershed 100-YR 500-YRLynnhaven Bay & River, Eastern BranchLynnhaven Bay & River, Incl. all areas other than Eastern Branch Chesapeake BayAtlantic Ocean & Rudee InletBack Bay, North of Beggars Bridge CreekBack Bay, South of Beggars Bridge CreekNorth Landing RiverElizabeth RiverNotes: Table J-12Design Tidal Elevations for Virginia BeachAll Elevations in feet relative to the North American Vertical Datum (NAVD) of 1988Location Design Level 1-YR 2-YR 3-YR 5-YR 10-YR 25-YR 50-YRStructural Protection22Structural Flood Risk ReductionKey Activities: • Investigate coastal flood pathways• Identify locations for flood risk reduction• Develop flood risk reduction alternatives • Assess feasibility and performance• Provide recommendations 23Structural Alternative Levels24Protect Most of CityDesigned to Future 100-yr floodCost: High (Billions)Protect High Risk AreasDesigned to Future 10- to 50-yr floodCost: Moderate (100s Millions)Address High Risk PropertiesAlternative to StructuresCost: Low to Moderate (Millions)City-wide Protection Alternatives• Limitations: • High-level concepts • Alignments based on desktop analysis • Each alignment will have major impacts and concerns which are not captured in detail • Drainage, Environmental, Traffic and Circulation, Navigation, Real Estate, Costs, Constructability, etc…• Initial results today – final results pending25Coastal Flood Protection Toolkit26Putting the Pieces Together• Collaborative review of possiblealignments• Identifying combinations of alignments• Culling options27Conceptualized Alignment Locations281.   Lynnhaven Inlet 2.   Long Canal3.   Upper West Branch Lynnhaven4.   Lower West Branch Lynnhaven5.   Upper East Branch Lynnhaven6.   Lower East Branch Lynnhaven7.   Rudee Inlet8.   Elizabeth River9. West Neck Creek Bridge10. Knotts Island11. Sandbridge Road12. Muddy Creek Road123456 789111210Combinations for Evaluation29Alternative 1 Alternative 2 Alternative 3 Alternative 4 Alternative 5Alternative 6 Alternative 7 Alternative 8 Alternative 9 Alternative 10Model Evaluation• DHI MIKE21• Stormwater runoff viaMIKE FLOOD• Tidal calibrated, validated• 10-/100-yr surge forcingwith/without 10-yr runoff• Structure implementation• Flood depth benefits and adverse impacts30Model Evaluation Benefits and Impacts31Areas of Benefit(reduced flood depth)Areas of Adverse Impact(increased flood depth)FOR INFORMATIONAL PURPOSESInitial values shown, currently under refinementConceptual Alignments321.   Lynnhaven Inlet 2.   Long Canal3.   Upper West Branch Lynnhaven4.   Lower West Branch Lynnhaven5.   Upper East Branch Lynnhaven6.   Lower East Branch Lynnhaven7.   Rudee Inlet8.   Elizabeth River9. West Neck Creek Bridge10. Knotts Island11. Sandbridge Road12. Muddy Creek Road123456 789111210Down-selection of Alternatives33Alternative 1 Alternative 2 Alternative 3 Alternative 4 Alternative 5Alternative 6 Alternative 7 Alternative 8 Alternative 9 Alternative 10Down-selected Alternatives349a 9bDown-selected Alternatives356 8Down-selected Alternatives362 4Renderings – Lynnhaven Inlet37Renderings – Lynnhaven Inlet38Renderings – Muddy Creek Rd39Renderings – Muddy Creek Rd40Cost Estimation• Rough Order of Magnitude*• Utilized ArcGIS and AutoCAD • Units costs from USACE, PIANC, etc.• Average parameters by unit length• Contingencies for: • Hard Construction Cost • Soft Costs • Escalation for futuredate of construction41*Approximate equivalent to Association for the Advancement of Cost Engineering Class 5 estimate for conceptual engineering phaseDown-Selected Alternative Summary42*Values subject to change pending final modeling and cost adjustments for gate types**Cost includes flood barrier in Norfolk that benefits Virginia Beach, Norfolk, and Chesapeake***Final count to be determined from model runsFOR INFORMATIONAL PURPOSESInitial values shown, currently under refinementSUMMARY OF ALTERNATIVES*ITEMSCITYWIDE ALTERNATIVES2 4 6 8 9aApproximate Overall Structure Length (miles) 33.8 34.5 33.0 26.1 11.1Flooded Area Reduction (square miles) -27 -28 -23 -24 -18Mitigated Structures(thousands) 45.5 43.1 40.1 36.5 27-13.8***Total Design & Construction Cost  (Billion USD 2018)$3.79** $2.73** $2.77 $1.71 $2.81Adjacent MunicipalAreas AffectedNorth Carolina,Norfolk, ChesapeakeNorth Carolina,Norfolk, ChesapeakeNorth Carolina,NorfolkNorth Carolina,NorfolkNorfolk$12 $271 $0$50$100$150$200$250$300Baseline Scenario 3 ft SLR ScenarioAnnualized Losses (Millions)Future With/Without Alternatives43Losses without ProjectLosses with Project Alternatives2 4 6 8Next Steps44City-wide ProjectionSite/Parcel StrategiesNeighborhood ProtectionHybrid AlternativesDraft Adaptation PlanReview &Stakeholder Engagement• Finalize evaluation• Complete for 5 locations• Key opportunities• Aggregate Benefits over Areas• What’s the best mix? • Study SynthesisNext 3-4 MonthsDiscussion45

Pivoting to the Future: Resiliency Planning in Virginia Beach

https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1004&context=hraforum_23

Pivoting to the Future: Resiliency Planning in Virginia Beach

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