The rainy season has not yet ended. As I write this, I look out my office window and watch as the rains fall. For nearly 12 hours the rain has been falling in an inconsistent pattern- stopping and starting again for a total accumulation of well over 1 inch. For my family’s property, that equates to more than a quarter million gallons of water. Fortunately, our home is built on a stem-wall and we have a water retention system built into our acreage. We are blessed, for sure, but not all our community members are so fortunate.
Yesterday’s BoCC meeting had many speakers for public speaking, but 1 in particular stood out. A resident of Salerno whose home has been inundated with flood waters repeatedly over the last several months. A retention pond had recently been built behind her home, and the land across the street has been under development for some time as the future home to a PUD community. When the rains come, they do as all water does: follows the path of least resistance and allows gravity to do its job. Unfortunately, gravity has not been kind to Mrs. Cook. Her residence (which she has called home for nearly 4 decades), was constructed at a much lower elevation than the adjacent properties. This is not a fault of hers, but instead an unintended consequence of Florida building code alteration and its practical application in conjunction with infrastructure maintenance. Couple these issues with loss of natural water retention and development of non-permeable infrastructure and you have a perfect storm to cause flood damage to a home not considered in a flood plain. This is what has happened in Salerno, a common tale in Hobe Sound, and an increasing threat in all of Martin County.
I have spoken in the past about how our patch work development in Martin has failed to curtail mass population growth, but today I want to talk about the issue of flooding. Unfortunately, our community is now finding it’s time to pay the piper for our poor developmental plans, and the piper wants payment in gallons.
For those unaware, when you build a structure in the state of Florida, you are required to build your finished floor elevation (ground floor level) at a certain height over the crown of the road (apex of the road elevation over sea level). The purpose of this is simple. As water is shed off the roads during rain events, the adjacent properties remain elevated above the water level and as such force sheet flow rain into draining ditches and swales. A simple and effective practice, if all properties are developed in a similar fashion. This is where things get sticky: our development practices are anything but similar.
Take for example:
Home #1 is built in 1970. The required height above the crown of the road is 4”, and the road’s elevation is 10’ above sea-level. This particular owner wants to be extra careful, so they build there home on an 8” stem wall meaning their finished elevation is 11’ above sea-level. They do not flood.
Home #2 is built in 2020. The required height above the crown of the road is now 12”, and the roads elevation above sea-level is 11’. Home #2 has a finished floor elevation set at the minimum of 12” and the elevation above sea-level is set at 12 feet. Home #2 is now a full 1 foot higher than home #1, and home #1 is now flooded.
So how did home #1 start with an 8-inch safety buffer and end with a 12-inch deficit? That’s fairly simple. The progress of time and the building codes do not take into account existing and adjacent structures. They only account for the needs of a new build. Additionally, you may have noticed the roads elevation changed. When a road is resurfaced, they are almost never fully excavated and replaced. Instead, you remove the top layer, and resurface the existing road’s bedding and substructure. In a 50-year period, at a 2-inch growth, you only need to resurface once every 10 years to end with a growth of a foot. This growth is exponential when coupled with the additional requirements above the crown of the road for elevation of a new building.
As we continue to see massive redevelopment of lands in our urban services boundary, there is no question that this issue will no longer be the exception, but instead the rule. Building brand new communities adjacent to half century old homes is not a cohesive plan, and certainly not accounted for in our infrastructure. At some point we must account for the effects of infill on our existing residences. At some point we must decide when infill is no longer practical, and where we should build out next. The patchwork application of our development, and obstinance to discussing and planning an expansion of the USB will only lead to more flooding, and more tax dollars spent to fix it. Just as the county continues to purchase homes in Hobe Sound to address flooding from new development (just as we purchased homes in Stuart to address sound issues at the airport), it appears that Salerno may become the next taxpayers land grab. Not for services, and not for Parks and recreation, but instead a reactive buy out of residents whose homes were made un-inhabitable because of poor forward planning by those who were supposed to represent them.