At its November 16, 2022, meeting, the City Commission approved item number C4J, a referral to the Public Safety and Neighborhood Quality of Life Committee to provide the Committee with an update and discussion of lessons learned during the October 2022 King Tide events, and additional improvements or enhancements that could be undertaken to address flooding issues in low-lying areas of the City.

As part of this referral, the City Administration is to provide the Committee with an update identifying low-lying areas where City’s flood mitigation efforts are working well, as well as any “hotspots” in the City where additional improvements and/or enhancements may be needed. City Commission requested the City Administration specifically review and advise the Committee regarding flooding in low-lying areas, as it is their understanding that these areas experienced excessive flooding during the King Tide cycle in October 2022.

BACKGROUND

The City of Miami Beach, a highly urbanized coastal community in southeast Florida and a major economic resource to the region, continues to be the leader in adapting to the impacts of climate change. The solutions to adapt present major challenges due to the relatively low-lying topography surrounded by intracoastal waterways with significant tidal influence, a subtropical climate with high intensity rainfalls, limited surface or soil storage for infiltration, and high amounts of impervious areas. Despite of all these challenges, investments in community-wide adaptation strategies are essential to protect property and communities from extreme high tides, gradual sea level rise and intense rainfalls. The City is working to implement comprehensive drainage and roadway projects to address flooding. We call these neighborhood improvement projects (NIPs), as they thoroughly address most of the critical infrastructure in the neighborhood, including robust upgrades to the drainage system by installing new pipes, large stormwater pump stations, and by elevating roads and sidewalks. NIPs are the only sustainable approach in the long term, especially for extremely low areas.

While the City recently approved major resilience adaptation strategies and the prioritization of NIPs City-wide, the implementation of these NIPs will require a major financial undertaking and will take several decades to complete.

Understanding the City’s vulnerability is an important foundation for risk reduction and projects.  The City’s Vulnerability Assessment and Adaptation Plan was recently funded by Resilient Florida. This project will build off of and improve the previous 2017 assessment by considering additional sea level rise scenarios, adding critical community facilities, and evaluating compound flooding due to a combination of rainfall and sea level rise. Additionally, the new assessment will include an analysis of social vulnerability and will conduct robust community engagement activities as part of the scope. In addition to analyzing current and future flood risk of all City assets, this project will also produce a comprehensive plan to address the risks, providing a phased implementation plan of adaptation strategies to guide the City’s future resilience planning efforts. The completion of the Vulnerability Assessment is also integral for the City to be eligible to continue to apply for and receive future Resilient Florida funding.

Completed Stormwater and NIP Related Studies

The City of Miami Beach (City) has completed several studies over the last five years; these include the Road Elevation Strategy and Neighborhood Project Prioritization, Blue-Green Stormwater Infrastructure, Stormwater Facilities Plan, Seawall Prioritization Plan, Basin Drainage Reports for the Flood Mitigation Study, and the latest 20-Year Stormwater Needs Analysis—completed in June 2022 according to Sections 403.9301 and 403.9302, Florida Statutes.

Stormwater Master Plan Update and Financial Feasibility Study

The City’s current approved Stormwater Master Plan is over 11 years old, and thus staff is in the process of completing a new Stormwater Master Plan, with the goal of incorporating all these recent studies into a 2023 City-wide Stormwater Master Plan and Capital Improvement Plan, which will help the City guide its stormwater program for the next 10 years, with longer term consideration and guidance through the next several decades.

This project began on October 14, 2022 and the goal of this project is to develop a Capital Improvement Plan to help implement drainage improvements for critical areas, as well as incorporate the long term plan for NIPs, with stormwater improvements, road elevation strategy as well as incorporate Blue-Green Stormwater Infrastructure as part of future projects. The Master Plan will look at the possibility of fast-tracking and prioritizing smaller-scale critical-needs improvements that could be a complementary part of a planned Neighborhood Improvement Project but where implementation could be expedited ahead of a scheduled Neighborhood Improvement Project. Figure 1 presents a summary of the ongoing analysis of areas that experience recurring flooding. The Consultant will be assessing the City and its infrastructure to recommend the critical areas that require improvements and could significantly benefit from smaller scale upgrades. The resulting Capital Improvement Plan and the associated funding will be presented to the community and to Commission for review, input and ultimate adoption and implementation. 

In the meantime, the City continues to deploy temporary pumps and use vacuum trucks to alleviate flooding to the extent possible. The Public Works team is committed to meeting or exceeding system maintenance goals so the existing drainage system works as best as it can.

Furthermore, the Public Works Department engaged GovRates, Inc. to update the prior Stormwater Rate Study, which was completed in 2017.  The aim of the updated stormwater rate study is to evaluate the current financial position of the Enterprise Fund, and to develop a funding plan for operational expenses and capital improvement needs.  Since NIPs are partially funded also by water and sewer funds, another analysis related to those rates is also underway. Upon completion, the updated rate study will provide the City with funding and rate scenarios that are useful tools in determining which variables need to be adjusted or changes that need to be implemented to achieve the desired financial results.

Ongoing NIPs

in parallel, the Administration continues to work on the execution of previously approved NIPs, including the following:

• Indian Creek Drive (roadway and drainage portions completed, seawall construction is ongoing and reaching completion in 2023)
• West Avenue Phase II (construction of North Segment scheduled to start April 2023)
• First Street (detailed design phase ongoing)
• North Shore D – North Beach Town Center (currently in design procurement, following execution of $10 M grant agreement)

2022 King Tides and Completed Resilience Projects

Figure 2 provides tide elevation and rainfall data during fall king tides of 2022. It illustrates how the highest tides generally approached elevation of 2.0 ft, with an extreme high tide in early November with minimal surge impact from Hurricane Ian. Figure 3 provides a map of the City showing roadway elevations. This map shows that significant areas within the City currently have elevations lower than 2.0 ft. These generally suffer some level of flooding regularly during king tides, and the flooding can be exacerbated by the combination of heavy rainfall during the extreme high tides. Road raising is a critical tool in our toolbox to address climate change and sea level rise, which will ultimately bring higher king tides and more frequent, heavier rainfall events. The implementation of the Neighborhood Improvement Projects, with road raising, robust stormwater collection, water quality treatment and pumping stations, along with the needed water and sewer infrastructure replacement, are key to mitigate these future conditions.

Areas that have already undergone this type of improvements, such as Sunset Harbour and Indian Creek avoided 49 days of flooding in the period of September 1st to November 30th, 2022.