Saving 450 Years of History from Tidal Flooding in St Augustine, Florida

St Augustine, south of Jacksonville in St. Johns County, has an urban population of approximately 13,000. It was founded in 1565 by the Spanish admiral Pedro Menéndez de Avilés, Florida's first governor. Spain ceded Florida to USA in 1819 and St Augustine remained the territorial capital until 1824. Given St. Augustine's distinct historical character the city is a major tourist attraction with many people coming to experience the architecture and history in the city. Access to the Atlantic Ocean is via the St. Augustine Inlet of the Matanzas River. The city has been largely unscathed during its long history, however in recent years flooding has become a problem, putting the buildings at risk of damage and decay. With an elevation just above sea level the city is at risk with rising sea levels and increased storm occurrences.

One such event occurred on October 7, 2016 when Hurricane Matthew caused widespread flooding in downtown St. Augustine.(1) During the hurricane the city’s streets flooded, largely due to the overtaxed and aged storm sewer system.(2)

The effects of Hurricane Matthew were profound. With the downtown inundated residents were left with the clean-up task of pulling down walls, replacing water damaged furniture and restoring the Spanish colonial style buildings to their original glory.

This old city is doing what it can to handle new threats. They have begun installing valves to keep seawater from flowing back into storm water drains, which helps prevent sunny day flooding. They have also been conducting a study with a plan to dredge Maria Sanchez Lake and install a pump station to help during flood events.

St. Augustine is one of many chronically flooded communities along Florida’s coast, and officials in these diverse places share a concern: They are afraid their buildings and communities will be further inundated by rising seas in just a couple of decades. The effects are a daily reality in much of Florida. Drinking water wells are being fouled by seawater. Higher tides and storm surges make for more frequent road flooding from Jacksonville to Key West, and they are overburdening aging flood-control systems(3). By working together, the communities along the coast of Florida can learn from each other about best practices and successful techniques.

St Augustine did just that when looking at outfall protection. Fort Lauderdale has recently undertaken a major project of upgrading their outfalls to protect against sunny day flooding and flooding caused by backflow from the sea into the stormwater systems.

In the presentation we will discuss the issues surrounding flooding in St Augustine, what was learnt during the research phase and what technical solutions St Augustine are implementing to solve a problem that affects many low-lying communities in the US, and around the world. We will also talk about the results of the project and discuss the best practices implemented in the project.