Lakeview Stormwater Improvements Presentation
On the evening of April 2, 2019, several elected commissioners, City of Miami Beach Assistant City Managers and leaders of the Public Works and Environment and Sustainability Departments, joined the Lakeview Homeowners Association to provide detailed information regarding the storm water improvement projects under consideration for the Lakeview neighborhood.
Assistant City Manager Eric Carpenter, Public Works Director Roy Coley, and Environment and Sustainability Director Elizabeth Wheaton offered homeowners an inside look at the current conditions of the water and sewer system and the flood risks to insufficiently elevated roads within the subdivision.
The presentation is available on this page for the reference of all residents.
Also in attendance were:
- Commissioner John Elizabeth Alemán
- Assistant City Manager Susy Torriente
- City Engineer Nelson Perez-Jacome
- Assistant City Engineer Luis Soto
- Infrastructure Director Rodolfo De La Torre
- Assistant Director of Marketing Communications Melissa Berthier
- Public Information Officer Liz Bello-Matthews
- Key factors impacting the need for considerable storm water improvements in the Lakeview subdivision:
- Tuberculation: in many cases, water lines were installed 50-60 years ago. Over time deposits of iron containing compounds (aka ferrous iron) accumulate inside the water lines restricting the flow. Although this does not affect the drinkability of water, it does substantially decrease water pressure.
- Decaying wastewater systems: as sewers get small cracks, roots grow inside the pipes preventing waste flow and resulting in system failures.
- Restricted city accessibility to easements: a consent order by the USEPA (United States Environmental Protection Agency) and the State of Florida are requiring the proper maintenance of easement. Oftentimes, sewer lines run behind properties throughout the Lakeview subdivision. The City requires that the easements be cleared and provide open access to the sewer lines, or the lines must be moved to the roadway to achieve adequate access for maintenance.
- The City installed 42 wells to monitor groundwater conditions. Through this analysis, engineers concluded that when the city experiences extremely high tides, it also faces extremely high groundwater, which does not allow any space for rain water. As a result, in areas of low elevation, when tides rise, water backflows into the system and begins to go up into the streets. Rainwater augments the problem causing flooding.
- The City is planning designs that anticipate sea levels rising 12” in the next 30 years, which is consistent with projections by the Southeast Florida Regional Climate Change Compact.
- The center of the road elevation – also known as the crown of the road – is set at 3.7 feet NAVD (North American Vertical Datum). This criterion considers requirements by the FDOT (Federal Department of Transportation) to design roads at least 3 feet above high groundwater. Review slides 32-34 for detailed road elevation illustrations, as well as a map noting the elevation levels of the Lakeview subdivision.
- The City has evaluated the pros and cons of a variety of storm water management methods, including: Shallow Gravity Wells, Gravity Outfalls, Pumped Outfalls, Shallow Injection Wells with Pollution Control, Deep Injection Wells, and Shallow Injection Well with Pollution Control. Reference slides 36-48 for an analysis of all.
- Pollution control and water quality are top-of-mind in the improvement considerations. The neighborhood has 19 gravity-based outfalls to surrounding waterways. Jacobs Engineering Group is currently evaluating transitioning to one pumped-based storm water outfall and will either validate the existing recommendations or provide a variation to the design. Jacobs Engineering Group has also been tasked to evaluate the utilization of infrastructure to protect the fresh water lens that enables native vegetation in the City.