MIAMIDADE BACK BAY COASTAL STORM RISK MANAGEMENT FEASIBILITY

MIAMI-DADE BACK BAY COASTAL STORM RISK MANAGEMENT FEASIBILITY STUDY 237 237 217 217 200 200 0 163 163 131 132 122 80 119 27 252 174. 59 110 135 120 112 92 56 PROJECT UPDATE FOR: MAYOR DANIELLA LEVINE CAVA , MIAMI-DADE COUNTY 255 255 239 65 53 62 102 130 102 56 48 130 120 111 Colonel Jason Kelly Commander, USACE South Atlantic Division Date: 14 January 2021 “The views, opinions and findings contained in this report are those of the authors(s) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by other official documentation. ” 1

KEY DISCUSSION POINTS q Current Situation: q Conducting outreach to inform key leaders q USACE Agency Decision Milestone required for study completion, September 2021 q Coordinating closely with Miami-Dade County – Non-Federal Project Sponsor q Feedback received from local Municipalities and the public (next slide) q Natural and nature-based features vs. structural solutions q USACE Civil Works Process – significant flexibility after Congressional Authorization q Feasibility study phase – “concept” design only; goal is Congressional Authorization in WRDA q Exact locations and designs of all structural measures will be determined in Preconstruction and Engineering Design (PED) phase q Sponsor has opportunity to consider & add betterments – e. g. , walkways, bike paths, levees. q Opportunity to reduce long term coastal storm risk 2

FEEDBACK FROM STAKEHOLDERS Description / Concerns USACE Action Develop briefings for Sponsor and other Municipalities Planned engagements with the Miami DDA, City Commissioners Reyes and Russell, SFWMD, etc. Develop additional outreach opportunities for community Future opportunities for community participation are included during Preconstruction, Engineering and Design (PED). Develop visual concept art for structural features and show height of recommended walls Approximate wall heights throughout all alignments have been calculated and shown in maps. Further designs will be completed in PED. Details on integrating project into Central Additional details will be included in study. SFWMD and Southern Florida (C&SF) Flood Jacksonville District updating the C&SF project in the future. Control Project This study will be included in that update. Provide more details on NNBF and/or replace walls with NNBF Fact sheets have been drafted to show more details and limitations of NNBFs would not provide the level of risk reduction similar to a structural measure. The walls will block views The Sponsor has opportunity to add betterments such as elevated walkways/bike paths. 3

RECOMMENDED PLAN INUNDATION BOUNDARIES Structural Area # of Structures with Potential Risk Reduction for City of Miami River 28, 000 Little River 4, 000 Coral Gables Way 10, 000 Note: The inundation layers are based on the USACE 0. 5% annual exceedance probability mean value confidence level for the year 2084. The 2084 value is the total water level which includes astronomical tides, storm surge, and USACE high curve sea level change for a particular storm event. FUTURE WITHOUT PROJECT FUTURE WITH PROJECT 4

STUDY AUTHORIZATION AND COUNTY -WIDE RECOMMENDED PLAN Study Authorization: q Bipartisan Budget Act of 2018, Public Law 115 -123, Title IV, Division B q Authorizes the Study at full Federal expense q Part of a multi-phase county-wide resilient investigation Total Project First Cost : $6, 058, 000 BCR: 10. 9 Annual Net benefits: $2, 798, 000 q Miami-Dade CSRM (beach study), South Atlantic Coastal Study, Miami -Dade Back Bay q Due to complexities, additional studies are required to cover all of Miami-Dade County q Close collaboration with the County ongoing Recommended Plan: q Floodproofing approximately 200 x critical infrastructure facilities q 7 x high risk focus areas featuring structural, nonstructural and/or NNBFs. q Structural measures: q Surge barriers, floodwalls, and pump stations at Biscayne Canal, Little River, Miami River, Coral Gables Way, and S 22 (Snapper Creek Canal). q Potential storm surge risk reduction to 220, 000 structures. q Nonstructural measures: q Elevating residential buildings: 5, 800 q Floodproofing non-residential buildings: 4, 600 q NNBFs were identified through coordination with local stakeholders, State agencies, and Federal agencies. 5

RECOMMENDED PLAN WITHIN CITY OF MIAMI q Approximately 25 critical infrastructure recommended for floodproofing on priority asset categories such as fire stations, police stations, hospitals, pump stations, and treatment plants. q Structural measures provide potential storm surge risk reduction to 42, 000 structures q Nonstructural measures: q Elevating residential buildings: 600 q Floodproofing non-residential buildings: 250 City of Miami q NNBFs were considered, but were screened out due to water velocities/surge in this area and water depth issues. q NNBFs would not provide the level of risk reduction similar to a structural measure. 6

DESIGN WATER SURFACE ELEVATIONS AND ALIGNMENTS Structural Area Range of Top of Wall Elevations for Floodwalls and Surge Barriers (ft. NAVD 88) Miami River 15. 6 – 19. 3 Little River 10. 7 – 14. 6 Biscayne Canal 11. 6 - 13 North Floodwall Surge Barrier q Feasibility level of design. Actual wall heights, alignments, and design will be determined during PED through the Sponsor and public input. South Wall in Water q Coastal walls utilized additional height to address wave overtopping rates. q Betterments such as elevated walkways, plantings, bike paths can be accommodated at Sponsor expense City of Miami Boundary ends here South Floodwall MIAMI RIVER LITTLE RIVER AND BISCAYNE CANAL 7

EXAMPLE FLOODWALL DESIGNS Richmond, VA Floodwall Road closure Norfolk, VA Floodwall Example of a sector gate (Miami River) Example of a miter gate (Little River) 8 8

APPLICATION OF BETTERMENTS Baywalk Example of public access (Brickell Waterfront) 9 9

CURRENT FEASIBILITY STUDY MILESTONE SCHEDULE Signing of Feasibility Cost Share Agreement (CW 130) 09 Oct 2018 (A) Alternatives Milestone (CW 261) 09 Jan 2019 (A) In-Progress Review 07 May 2019 (A) Tentatively Selected Plan Milestone (CW 262) 17 Jan 2020 (A) Release of Draft Study for Concurrent Reviews (CW 250) 5 June 2020 (A) Agency Decision Milestone (CW 263) 18 Nov 2020 (A) 2 nd Agency Decision Milestone 19 Feb 2021 (S) Submit Final Report Package to MSC / Policy and Legal Compliance Review Team (CW 160) 23 April 2021 (S) State and Agency Review 11 June 2021 (S) Signed Chief’s Report (CW 270) 24 Sep 2021 (S) 10

QUESTIONS? 11

BACKUP SLIDES 34

MIAMI RIVER DESIGN WATER SURFACE ELEVATION AND ALIGNMENTS Miami River Structural Breakdown Top of Wall Elevation (ft. NAVD 88) Average ground elevation for floodwalls range from 5 to 8’ NAVD 88 South Floodwall 15. 6 South Wall in Water 19. 3 Surge Barrier North Floodwall 19 16. 1 Surge Barrier Note: Stillwater levels were based on the 50% confidence levels which included storm surge, tides, USACE high curve sea level change and wave setup. q Feasibility level of design. Actual wall heights, alignments, and design will be determined during PED through the Sponsor and public input. South Wall in Water q Coastal walls utilized additional height to address wave overtopping rates. q Betterments such as elevated walkways, plantings, bike paths can be accommodated at Sponsor expense South Floodwall 13

LITTLE RIVER DESIGN WATER SURFACE ELEVATION AND ALIGNMENTS Structural Area Biscayne Canal Little River Structural Breakdown Top of Wall Elevation (ft. NAVD 88) Avg. ground elevation for floodwalls range from 5’ to 8’ NAVD 88 South Floodwall 11. 6 Surge Barrier 13 North Floodwall 13 South Floodwall 10. 7 Surge Barrier 14. 6 North Floodwall 14. 4 City of Miami Boundary ends here Note: Stillwater levels were based on the 50% confidence levels which included storm surge, tides, USACE high curve sea level change and wave setup. q Feasibility level of design. Actual wall heights, alignments, and design will be determined during PED through the Sponsor and public input. q Walls further inland utilized natural high ground to reduce the wall height 14

DESIGN WATER SURFACE ELEVATION AND ALIGNMENTS Structural Area Miami River Little River Biscayne Canal Structural Breakdown Top of Wall Elevation (ft. NAVD 88) South Floodwall 15. 6 South Wall in Water 19. 3 Surge Barrier North Floodwall 19 North Floodwall 16. 1 South Floodwall 10. 7 Surge Barrier 14. 6 North Floodwall 14. 4 South Floodwall 11. 6 Surge Barrier 13 North Floodwall 13 q Feasibility level of design. Actual wall heights, alignments, and design will be determined during PED through the Sponsor and public input. q Coastal walls utilized additional height to address wave overtopping rates. q Betterments such as elevated walkways/bike paths, plantings, etc. can be accommodated at Sponsor expense Surge Barrier City of Miami Boundary ends here South Wall in Water South Floodwall MIAMI RIVER LITTLE RIVER AND BISCAYNE CANAL 15

ENVIRONMENTAL COORDINATION q Notice of Intent to prepare an Environmental Impact Statement (EIS) published 18 July 2019; Notice of Availability of draft Integrated Feasibility Report and Programmatic EIS published 5 June 2020 q Interagency meetings held approximately bi-monthly q Participating/Cooperating Agencies: q q q q q Florida Department of Environmental Protection Biscayne Bay Aquatic Preserve Florida Department of Transportation* U. S. Fish and Wildlife Service National Park Service Federal Emergency Management Agency National Marine Fisheries Service * U. S. Environmental Protection Agency* U. S. Coast Guard South Florida Water Management District * = Cooperating Agencies 22

IMPLEMENTATION OF RECOMMENDED PLAN Measure Approximate Duration (Years) FY Start FY End Priority Critical Infrastructure 10 2026 2035 1 Nonstructural Measures 10 2026 2035 2 NNBF - Cutler Bay 5 2026 2030 3 Miami River Surge Barrier and associated features 10 2026 2035 4 Little River Surge Barrier and associated features 3 2028 2030 5 Biscayne Canal Surge Barrier and associated features 5 2031 2035 5 Mitigation (prior to construction of respective feature) 11 2025 2035 - q Implementation strategy discussed and agreed upon with Miami-Dade County q Critical infrastructure and nonstructural measures are first due to less design and construction time q Larger structural measures could still be in PED, obtaining permits, etc. 17