Techno-Economic Assessment of Liquefaction Mitigation by Microbially Induced Desaturation

Microbially induced desaturation (MID) is a novel, minimally disruptive biogeochemical technique for mitigating the potential for triggering earthquake-induced soil liquefaction. In MID, native microorganisms are stimulated to produce relatively insoluble nitrogen biogas, thereby desaturating the soil. Its minimally disruptive nature makes MID particularly attractive for mitigating liquefaction triggering beneath and around existing facilities, where current mitigation techniques are generally either not applicable due to their disruptive nature or too costly to be economically viable for all but the most critical facilities. Considering the large inventory of existing infrastructure built on or in potentially liquefiable soil, a cost-effective means of mitigating triggering of liquefaction in a minimally disruptively manner could significantly enhance seismic resilience worldwide. The key technical factors influencing the effectiveness of MID for mitigation of liquefaction triggering include delivery of the nutrients for generation of biogas in the liquefaction susceptible soils, the persistence of the induced desaturation, and the impact of local environmental conditions, including groundwater pH and the presence of alternative electron acceptors, e.g., sulfate. Economic analysis suggests that if these technical factors can be managed, MID can be a cost-effective means to mitigate liquefaction triggering beneath and around existing infrastructure.