Abstract
There are approximately 2.6 million onsite sewage treatment and disposal systems (OSTDS) in the State of Florida (Ursin, 2016). Of these, approximately 120,000 are located in Miami-Dade County (MDC) (WASD, 2020).
To operate effectively, OSTDS require sufficient levels of unsaturated soils beneath them (MDC, 2018). Percolation through unsaturated soil is necessary to provide effective treatment of effluent prior to its entering groundwater. The density of OSTDS in a region is also critical. High levels of OSTDS density have been found to increase contamination of ground water (University of Florida, 1987).Unfortunately, thousands of OSTDS installed in MDC do not have sufficient vertical separation from groundwater and were installed in highly dense concentrations. Now, elevated groundwater levels resulting from sea level rise and increasing storm events (MDC, 2018) make these OSTDS highly vulnerable to failure (MDC, 2018). Approximately 56% of systems are already periodically compromised each year and this number is expected to rise to 64% by 2040 (MDC, 2018). When an OSTDS fails, substantial amounts of pathogenic human organisms, anthropogenic nutrients, and other pollutants are discharged directly into groundwater and transmitted to surrounding waterways posing a significant threat to public health and the environment. Adverse impacts from failed septic tanks in MDC are occurring in the form of increased frequency and severity of algal blooms, massive seagrass die-offs and fish kills in portions of Biscayne Bay. The most straightforward solution is to convert existing OSTDS to sewer systems. Over the course of my internship I identified many challenges that must be successfully navigated to reach this septic to sewer goal. Challenges include financial, regulatory, cultural, and political barriers. Public support will be needed to foster the political will needed to advocate for solutions.
A series of specific short-term goals and action items are provided to lay a path towards reaching the long-term goal of eliminating conventional septic tanks from MDC.