SBIR Phase I: Microbially-Driven Underground Barrier to Reduce Flooding in Coastal Communities

The broader/commercial impact of this Small Business Innovation Research (SBIR) Phase I project is to develop a microbially-driven method to reduce flooding in coastal communities built on highly permeable coral limestone soil formations, such as those found in South Florida. With sea levels projected to rise 10-12 inches by 2050 along the U.S. coasts, barriers to prevent flooding are needed. Currently proposed methods rely on building extensive infrastructure both above and below land or moving residents to higher elevations, all of which are intrusive to the day-to-day lives of Americans. This project aims to prevent flooding in communities built on limestone soil by modifying the permeability of limestone using naturally occurring bacteria. Reducing the permeability of limestone will prevent underground water from rising into communities. The approach is less invasive than existing technologies, does not require excessive excavation, and may allow citizens to remain in their homes despite the sea level rise. It addresses NSF’s mission to ensure the prosperity of the average American citizen. It also involves stakeholders across multiple industries, including industrial microbiology, geochemistry, and construction, and can be applied to large areas of the US, thus potentially creating jobs and tax revenues from many sources. Microbially-induced carbonate precipitation (MICP), a process that uses naturally occurring bacteria to create calcium carbonate crystals on surfaces, will be employed to reduce the permeability of limestone to water. Upon optimizing and scaling this process, MICP will be used to modify in-ground limestone structures to reduce flooding in coastal communities. With this long-term goal in mind, and within the scope of an SBIR Phase I project, the goals of this proposal are to optimize the growth and MICP capabilities of naturally occurring bacterial strains in conditions that mimic the underground limestone environment and to test the structure, strength, and permeability of the MICP-modified limestone. The above will be accomplished using a suite of microbial growth and urease assays, biochemical and microscopy assessments of calcium carbonate deposits, and physio-chemical assessment of limestone porosity and bond strength. Together, the work proposed will establish the preferred conditions for MICP on limestone in environmentally relevant experimental conditions. This represents the first critical step towards using MICP in coastal communities to reduce or eliminate groundwater flooding as sea level waters rise. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.