CITY of VIRGINIA BEACH RESORT AREA STRATEGIC ACTION PLAN (RASAP) - PDF document

CITY of VIRGINIA BEACH RESORT AREA STRATEGIC ACTION PLAN (RASAP) Steering Committee Agenda Monday, October 7th [2:00pm-4:30pm] AGENDA 2:00 City of Virginia Beach Sea Level Rise Study Brief - CJ Bodnar (20 minute presentation + 10 minute Q&A) 2:30 RASAP Steering Committee - working session • Review & discuss individual edits to the draft • Form consensus around edits and revisions to text and graphics 4:15 Schedule/Next Steps • RASAP Steering Committee Meeting – Thursday, 11/07/19 – 10 :00 – 12:00 @ CVB Board Room YARD & COMPANY Kevin is a leader in community development, economic and real estate development fjnance, have included several public and private partners and a diverse set of public fjnancing tools such

Sea Level Wise City of Virginia Beach Sea Level Rise Adaptation Study City of Virginia Beach, RASAP Steering Committee C.J. Bodnar, P.E. Public Works, Stormwater Engineering Center October 7, 2019

Moody’s Questionnaire to VB (2014) • Does the existing/future CIP include spending for mitigation or resiliency? • Has your governing body discussed the capital or financial implications of rising sea levels? • Has there been an estimate on potential impacts from rising sea levels or flooding? • Please discuss how flooding has impacted the city’s budget and how flood mitigation efforts may impact future budgets? • Have there been any zoning /long-term planning adjustments downtown and along the waterfront to mitigate future flooding impacts? • What is management’s current view on the potential impact/vulnerabilities in your community from rising sea levels and a heightened risk of extreme weather events? 2

Ongoing Studies Project Website: http://www.vbgov.com/pwSLR • Comprehensive Sea Level Rise and Recurrent Flooding Study • Assessing existing and future flood vulnerabilities and identifying strategies to ensure our city is resilient to future flooding events • Master Drainage Study • Detailed inventory and performance assessment of the City’s stormwater system • Stormwater Master Plan • Identification and prioritization of needed improvements to stormwater system 3

Combined Impact on Stormwater Analysis • Higher coastal water levels diminish stormwater system performance • Coastal Flooding • Stormwater Conveyance • Combined Flooding 4

Comprehensive Sea Level Rise and Recurrent Flood Study 5

Study Goal and Outcomes Goal: Produce information and strategies that will enable Virginia Beach to establish long-term resilience to sea level rise and associated recurrent flooding Outcomes: • Establish a full understanding of flood risk and anticipated changes over planning and infrastructure time horizons • Develop risk-informed strategies, including engineered protection and policy to reduce short and long-term impacts • Produce City-wide and watershed “action plans” for strategy implementation • Engage a fine-tuned public outreach process to advance resilience initiatives 6

Top 10% 7

Observed Acceleration Boon et al. 2018 https://www.vims.edu/research/products/slrc/index.php 8

VB SLR Planning Scenarios Sourced from: Consistent with: 9

Timeline of Activities 2016 2017 2018 2015 2019 Planning Study Progression Strategy Focus Synthesis • Scenarios • Grant award • Structural Alternatives • Neighborhood and site alternatives • City-wide concepts • Conceptual • Hazard and risk • Performance model assessment • Full Draft • Down-selection Adaptation • Essential analysis Strategy • Policy refinement to inform design and rankings • Stakeholder • Stormwater outreach and input coordination • Policy menu 10

Hazard and Risk Assessment Hazard and Risk-driven Decision-Making 11

Focus Areas for Adaptation 88% of City’s Risk 12

Consequences of Future Without Action Annualized Losses (Millions) $350 $300 $250 $200 $329 $150 $100 $50 $77 $26 $0 Baseline Scenario 1.5 ft SLR Scenario 3 ft SLR Scenario Compared to Today: 3x increase 12x increase 13

Informing Design • 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 tailwaters 14

Stormwater Design Standards 15

Public Works Design Standards Manual, 2019 • Major Design Standard Changes to Address Recurrent Flooding and Sea Level Rise: • Requirement to use EPA SWMM software modelling tool for designs with Drainage Area > 20 Ac. • Updated Revised Rainfall Depths Based on Future Precipitation Analysis (20% more) • Starting Boundary Conditions • Specific Requirements Relative to Hydraulic Grade Line • Requirement to use City Models Developed of all (31) Drainage Basins • Requirement to address Sea Level Rise • Requirement to address Groundwater Base Flow in Wet Ponds • Draft Manual Complete as of May 1 st • Public Comment Period: May 1 st through August 30 th • Engineering/Development Community Public Meeting Held August 21 st Draft Document can be found at: https://www.vbgov.com/government/departments/public-works/standards-specs/Pages/default.aspx 16

Adaptation Strategies Policy Design Protection Integrated Solution 17

Adaptation Strategies • Policy Response Document • City-wide Flood Protection Strategies • Individual Site-Level Strategies • Natural and Nature-based Solutions 18

Policy Document • 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 • Not a prescriptive document to be followed “to the letter” 19

Stormwater Design Standard Outputs Table J-12 Design Tidal Elevations for Virginia Beach All Elevations in feet relative to the North American Vertical Datum (NAVD) of 1988 Location Design Level 1-YR 2-YR 3-YR 5-YR 10-YR 25-YR 50-YR 100-YR 500-YR Existing Condition 3.1 3.6 4.0 4.4 5.2 5.8 6.2 6.7 8.5 Lynnhaven Bay & 1.5 ft SLR 4.6 5.1 5.5 5.9 6.7 7.3 7.7 8.2 10.0 River, Eastern Branch 3.0 ft SLR 6.3 6.9 7.3 7.7 8.5 9.2 9.6 10.1 12.0 Lynnhaven Bay & Existing Condition 3.2 3.9 4.3 4.8 5.5 6.3 6.9 7.4 9.3 River, Incl. all areas 1.5 ft SLR 4.7 5.4 5.8 6.3 7.0 7.8 8.4 8.9 10.8 other than Eastern 3.0 ft SLR 6.4 7.2 7.6 8.1 8.8 9.7 10.3 10.8 12.8 Existing Condition 3.2 3.8 4.1 4.5 5.2 5.9 6.5 7.1 8.5 1.5 ft SLR 4.7 5.3 5.6 6.0 6.7 7.4 8.0 8.6 10.0 Chesapeake Bay 3.0 ft SLR 6.4 7.1 7.4 7.8 8.5 9.3 9.9 10.5 12.0 Existing Condition 3.6 4.1 4.5 4.9 5.4 6.3 6.8 7.3 8.7 Atlantic Ocean & 1.5 ft SLR 5.1 5.6 6.0 6.4 6.9 7.8 8.3 8.8 10.2 Rudee Inlet 3.0 ft SLR 7.2 7.7 8.2 8.6 9.2 10.1 10.7 11.2 12.8 Back Bay, North of Existing Condition - - - 1.8 2.4 3.4 4.2 4.9 6.4 Beggars Bridge 1.5 ft SLR - - - 3.3 3.9 4.9 5.7 6.4 7.9 Creek 3.0 ft SLR - - - 6.7 7.6 9.0 10.1 11.1 13.2 Back Bay, South of Existing Condition - - - 1.5 1.9 2.4 2.8 3.3 4.2 Beggars Bridge 1.5 ft SLR - - - 3.0 3.4 3.9 4.3 4.8 5.7 Creek 3.0 ft SLR - - - 6.3 6.9 7.6 8.1 8.8 10.1 Existing Condition - - - 1.3 1.6 2.8 3.4 3.9 4.9 North Landing River 1.5 ft SLR - - - 2.8 3.1 4.3 4.9 5.4 6.4 3.0 ft SLR - - - 4.6 5.0 6.3 6.9 7.5 8.5 Existing Condition 2.8 3.6 4.1 4.7 5.8 6.5 7.1 7.9 10.3 Elizabeth River 1.5 ft SLR 4.3 5.1 5.6 6.2 7.3 8.0 8.6 9.4 11.8 3.0 ft SLR 5.9 6.7 7.2 7.8 8.9 9.6 10.2 11.0 13.4 Notes: 1. All elevations sourced from direct sampling and statistical analysis of the distribution of water elevations in each watershed 2. 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, WO2A 4. The values do not represent potential wind-driven water levels in the Back Bay and North Landing River 5. The 5-year return period should be used as a minimum elevation for design in Back Bay and North Landing River due to 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 Program 20

Flood Reduction Strategies Natural and Nature-based 21

City-wide Structural Flood Protection Strategies • Objective: • Close coastal flood pathways into city for maximum flood reduction benefit • Product • Conceptual solutions • Informs direction of detailed efforts • Metrics Assessed: • Cost • Cost-benefits • Flood reduction benefits 22

Location Renders – Lynnhaven 23

Location Renders – Lynnhaven 24

Location Renders – Oceanfront 25

Location Renders – Oceanfront 26

Location Renders – Rudee Inlet 27

Location Renders – Rudee Inlet 28