Field Implementation of Microbially Induced Calcium Carbonate Precipitation for Surface Erosion Reduction of a Coastal Plain Sandy Slope

Abstract

Over the past decade, several researchers have demonstrated that microbially induced carbonate precipitation (MICP) has the potential to improve soil behavior in the laboratory setting. In this study, MICP was implemented at a sandy slope field site to enhance erosion resistance and surficial soil strength. Three application systems—surface spraying, prefabricated vertical drains (PVDs), and shallow trenches—were compared. Improvement of the treated soil was assessed using dynamic cone penetration, impinging jet, and pocket penetrometer tests and was monitored for 331 days. Results indicated that MICP is an effective soil improvement method for surficial and deeper applications. Penetration index values improved up to 73% and 55% at the surface and a depth of 30 cm, respectively. Critical shear stress and coefficient of erodibility values exhibited significant improvements. The surface spraying method is preferred for the treatment of large surficial areas, whereas the PVD method demonstrated deep soil improvement potential. The shallow trenches resulted in significant surficial improvements, however, in a highly localized manner. Post-treatment monitoring indicated no significant degradation of the treated areas with time and after major storm events (e.g., Hurricane Dorian). Based on the field results, a sensitivity analysis was performed to address the applicability of future MICP-field implementations in various soil types.