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

The broader/ commercial impact of this Small Business Innovation Research (SBIR) Phase II project lies in mitigating escalating "bottom-up" flood risks by commercializing nature-based technology to reinforce porous limestone. This innovation reduces flood damage, saltwater intrusion, and seawall failure in at-risk coastal regions, such as Florida. By strengthening critical infrastructure and protecting natural resources, the project enhances public safety and quality of life while lowering long-term maintenance costs and minimizing resident disruption. Furthermore, this work advances the national interest in economic security and resource conservation, fulfilling the mission of translating scientific research into tangible public benefits through successful commercialization. The primary technical challenge of this project is determining whether controlled carbonate mineral formation can achieve the scale, uniformity, and durability required to create low-permeability subsurface barriers within porous coastal limestone. This is inherently high-risk due to the extreme heterogeneity of coastal geology, which is subject to high permeability, variable groundwater flow, and fluctuating chemical conditions from seawater intrusion. A successful outcome would establish a novel subsurface approach to restrict underground water movement and stabilize infrastructure in at-risk shoreline environments. This research investigates how biologically and chemically assisted mineral formation can be precisely directed within native limestone to enhance hydraulic and mechanical performance without compromising physico-chemical and biological compatibility. The project moves from laboratory validation to controlled large- scale testing and field demonstrations, specifically targeting seawall resilience in porous coastal settings. The core intellectual contribution lies in managing mineral formation within heterogeneous media to predictably reduce permeability and increase structural strength. The project employs a staged methodology: first, refining treatment conditions for improved reliability and scalability; second, evaluating performance in simulated limestone test systems that replicate field-level pore structures and other local variations; and finally, assessing behavior through controlled field injection trials. Supported by hydraulic measurements, mineralogical analysis, and subsurface imaging, these methods will establish the engineering foundation for a scalable resilience platform to combat flooding, saltwater intrusion, and coastal deterioration. 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.