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Microbially induced carbonate precipitation (MICP) has been shown to improve geotechnical properties of soil in many laboratory-scale tests. Field deployment of this technology requires large volumes of suspended bacterial inoculum media, and geotechnical engineers are still seeking a low-cost and quick method for upscaling applications. In this paper, we propose a four-step inoculation method to culture Sporoscarcina pasteurii for implementation of MICP in a prototypical dune in the Large Wave Flume at the O.H. Hinsdale Wave Research Laboratory of Oregon State University. The four-step inoculation method nonsterilely cultured the bacteria to 42 L in a common microbiology lab and scaled it up to 73 L in the field. The values of optical density at a wavelength of 600 nm (OD600) were obtained to determine the specific growth rate. Two different types of agar plates were evaluated for contamination and cell counting of the bacterial solutions. Shear-wave velocity of the treated dune was continuously measured by pairs of bender elements to monitor the treatment process. The average specific growth rates of the 42- and 73-L bacterial solutions were 5.11×10−3 and 1.27×10−3 min−1 , which were quite high compared with previous studies. The plate results indicated that the four-step inoculation method provided 108 cells/mL of bacterial solution with unobserved contamination. The increase in shear-wave velocity suggested the development of biocementation within sand particle contacts of the dune, demonstrating the effectiveness of the inoculation method. The results suggest that the four-step inoculation process discussed in this paper provides a large amount of bacterial solution for field-scale application of MICP. [ABSTRACT FROM AUTHOR]

In this study, the application of microbially induced carbonate precipitation for coastline protection was investigated. Untreated, moderately, and heavily cemented near-prototype dunes were fabricated in the largest wave flume in North America at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. Dunes were stabilized with two treatment application systems known as surface spraying and prefabricated vertical drains. Untreated and stabilized dunes were subjected to waves similar to Hurricane Sandy conditions recorded in New Jersey in 2012. Laboratory tests and in situ assessments were performed to quantify the improvement of mechanical properties of soil and investigate the performance of dunes subjected to extreme wave actions. Post-treatment cone penetration test sounding results indicated a significant cone tip resistance that was controlled by carbonate content and cementation distribution pattern. Similarly, monitoring the changes in the morphology of dunes demonstrated that the shear strength, cementation level, and cementation distribution pattern control the equilibrium beach profile, erosion rate, and mass loss. [ABSTRACT FROM AUTHOR]