Insights on Sewer Geyser Mechanisms and Retrofitting Strategies through Numerical Modeling and Laboratory Measurements

This paper offers a preliminary exploration of sewer geysers, commonly termed sewer blowouts, prevalent in combined sewer systems during intense precipitation. Through extensive large-scale experiments at the Engineering Center of Florida International University and a meticulous 3D numerical modeling approach utilizing OpenFOAM, the study unveils the intricate mechanisms governing geyser formation. The experimental setup, employing a novel approach, provides detailed insights into geyser eruption dynamics, while the numerical model employs a finite volume method, emphasizing a sharp air-water interface. The research introduces and evaluates two retrofitting strategies—Retrofitting Strategy I, involving the enlargement of a dropshaft section, and Retrofitting Strategy II, combining a bypass with an orifice plate. A comparative analysis showcases particular differences in pressure variations and ejection velocities, highlighting the potential of Retrofitting Strategy II in reducing pressure fluctuations. The study concludes that introducing an offset between the lower and upper dropshaft sections enhances the effectiveness of near-surface retrofitting, mitigating visible geyser eruptions. The findings underscore the necessity for ongoing field monitoring to refine and validate these retrofitting strategies. In summary, this paper helps to better understand sewer geysers, amalgamating experimental insights, numerical modeling, and practical retrofitting approaches to address challenges in stormsewer systems, providing a valuable resource for future research and infrastructure planning.