When you think of the Florida Keys, the first images and thoughts that come to mind are probably not in the potable water realm.
The Florida Keys Aqueduct Authority (FKAA) and its water system manage what may be one of the best-kept secrets of the Florida Keys: its 130-mile linear system pumps 20 million gallons of water per day to approximately 55,000 customers, and it is home to two low-pressure reverse osmosis (RO) treatment systems, with a third entering design in 2023.
Seawater reverse osmosis
The FKAA owns and operates the second-ever seawater reverse osmosis (RO) treatment plant in the world.
The technology allows FKAA to use seawater as an alternative potable water source and partially alleviate its reliance on the Biscayne and Floridan aquifers. It also provides relief for saltwater intrusion to protect these water sources long-term.
This is especially important during times of drought when the aquifers experience greater demand and a lower rate of recharge. In this way, RO treatment helps to protect critical habitats such as the Everglades during dry seasons.
The RO plants also provide redundancy in the system to avoid service interruptions during emergencies or when performing maintenance on pipelines. This is especially critical during hurricane season when high winds and storm surges put infrastructure at risk.
With RO water to supplement the main source water, customers are less likely to experience service interruptions during hurricanes or other climate-related weather events.
Commitment to Forward progress
While finding solutions to daily challenges is gratifying for the FKAA team, the authority maintains an unwavering commitment to remaining innovative and proactive. Staying stagnant, no pun intended, is never an option. Collaboratively, the team works day in and day out to push the needle forward. The authority maintains a culture that values solutions that are long-lasting and futuristic.
As of press time, the pre-construction meeting for a new legacy project took place. The goal: replacement of 4 miles of transmission main in Islamorada. The project will set the tide in motion for a decades-long project that will help the FKAA remain innovative.
Over the next 20 to 30 years, FKAA’s goal is to replace the entire transmission main of its 130-mile-long system, which includes 45 bridge crossings. Barring any delays, work will begin in Islamorada in April to replace the original transmission main that is roughly 60 years old. The old 30-inch ductile water main will be replaced with a new cathodically protected 36-inch steel pipe.
Additionally, the mains at the Tea Table Relief and Whale Harbor bridge crossings will be installed underwater via directional drilling to isolate them from the impacts of severe weather.
Extreme weather crises management
Storm surges, high winds and other climatic effects are nothing new for the Florida Keys. Made up of 1,700 islands, not one area of the coral cay archipelago sits more than 20 feet above sea level.
On Sept. 2, 1935, one of the worst hurricanes to ever hit the U.S. ravaged the Florida Keys. In the wake of winds greater than 200 miles per hour and a storm surge more than 17 feet tall, more than 500 people perished. Nearly a century later, storms are continuing to strengthen, making this effect of mother nature among the most important providers of one of the most precious resources.
FKAA’s project started with the village Islamorada, despite the impacts of climate change on the community, because it is already seeing the effects of aggressive soils and subterranean tidal flows that submerge and expose the pipeline to corrosive conditions.
Most of the authority’s buried infrastructure is at or below sea level. When buried transmission main undergoes tidal submersion and exposure, it begins to corrode. Corrosion of steel is an electrochemical process, and soil resistivity and water salinity have the greatest impact.
The subsurface conditions in the Florida Keys create this corrosive environment through a combination of saltwater and porous soils. Since the pipeline is submerged and unsubmerged repeatedly daily, this can cause severe corrosion without cathodic protection to absorb those effects.
Future plans in the Florida Keys
After work in Islamorada is complete, the authority has plans to replace a portion of the Key West transmission line, followed Plantation Key, and then others in turn until the entire system is upgraded with new steel pipes.
Once completed, the transmission main replacement project will improve water system reliability, reduce lost water, improve pumping efficiencies, and reduce the authority’s carbon footprint. In a time when climate change is becoming rapidly more pressing, it is imperative to remain proactive in how the utility approaches maintaining and improving water systems.
Funding a project of this magnitude is no easy feat. The initial 4-mile transmission line replacement project in Islamorada will cost approximately $42 million. Local partnerships were key to securing funding for this project. After meeting with leaders in the Village of Islamorada, they too saw the importance of the project.
Together, FKAA and Islamorada applied for and secured $35 million in state and federal grants. The remaining $7 million will be funded through a low-interest loan. Stakeholders anticipate they will continue to secure grants to help fund the replacement of the entire transmission main over the next couple of decades. WW
