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1. Resisting Dune Erosion with Bio-cementation

   Montoya, B. M. ( October 2021 , Proceedings of the 10th International Conference on Scour and Erosion)

   Coastal dunes often present the first line of defense for the built environment during extreme wave surge and storm events. In order to protect inland infrastructure, dunes must resist erosion in the face of these incidents. Microbial induced carbonate precipitation (MICP), or more commonly bio-cementation, can be used to increase the critical shear strength of sand and mitigate erosion. To evaluate the performance of bio-cemented dunes, prototypical dunes consisting of clean poorly graded sand collected from the Oregon coast were constructed within the Large Wave Flume at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. The bio-cementation treatmentmore »was sprayed onto the surface of the unsaturated dune. The level of cementation was monitored using shear wave velocity measurements throughout the duration of the treatments. The treated and control dunes were subjected to 19 trials of approximately 300 waves each, with each trial increasing in water depth, wave height, and wave period. The performance of the dune was evaluated using lidar scans between each wave trial. The results indicate that the surface spraying treatment technique produced consistent levels of bio-cementation throughout the treated length of the dune and demonstrated significant resistance to erosion from the wave trails.« less
2. Resisting Dune Erosion with Bio-cementation

   Montoya, B. M. ; Evans, T. M. ; Wengrove, M. E. ; Bond, H. ; Ghasemi, P. ; Yazdani, E. ; Dadashiserej, A. ; and Liu, Q. ( October 2021 , Proceedings of the 10th International Conference on Scour and Erosion (ICSE-10))

   Rice, J. ; Liu, X. ; Sasanakul, I. ; McIlroy, M. ; Xiao, M. (Ed.)

   Coastal dunes often present the first line of defense for the built environment during extreme wave surge and storm events. In order to protect inland infrastructure, dunes must resist erosion in the face of these incidents. Microbial induced carbonate precipitation (MICP), or more commonly bio-cementation, can be used to increase the critical shear strength of sand and mitigate erosion. To evaluate the performance of bio-cemented dunes, prototypical dunes consisting of clean poorly graded sand collected from the Oregon coast were constructed within the Large Wave Flume at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. The bio-cementation treatmentmore »was sprayed onto the surface of the unsaturated dune. The level of cementation was monitored using shear wave velocity measurements throughout the duration of the treatments. The treated and control dunes were subjected to 19 trials of approximately 300 waves each, with each trial increasing in water depth, wave height, and wave period. The performance of the dune was evaluated using lidar scans between each wave trial. The results indicate that the surface spraying treatment technique produced consistent levels of bio-cementation throughout the treated length of the dune and demonstrated significant resistance to erosion from the wave trails.« less
3. Experimental Study to Determine an EICP Application Method Feasible for Field Treatment for Soil Erosion Control

   https://doi.org/10.1061/9780784482834.023  

   Ossai, Rashidatu ; Rivera, Lucas ; Bandini, Paola ( February 2020 , Geo-Congress 2020: Biogeotechnics)

   The end goal of this research is assessing the feasibility of using enzyme induced carbonate precipitation (EICP) to create a cemented top layer to control runoff erosion in sloping sandy soil. The paper presents the results of an experimental study of bench-scale tests on EICP-treated sands to determine a treatment method feasible for field placement for this application. The soils tested were two natural sands and Ottawa 20-30 sand used as control. The EICP application methods were percolation by gravity, one-step mix-compact, and two-step mix-compact. Other conditions considered were pre-rinsing the sand prior to treatment, adjusting soil pH prior tomore »treatment, and changing the EICP solution concentration. Promising results for this field application were obtained using the two-step mix-compact when the soil was first mixed with the urease enzyme solution before compaction. Considering that the EICP reaction starts once all components are added, this method would ensure that the reaction does not take place before the protective layer of treated soil has been installed. The effect of pre-rinsing the natural sand was not consistent throughout the testing conditions and its role in improving soil cementation in natural sand needs further study.« less
4. Investigating the Effect of Microbial Activity and Chemical Concentrations on the Mineralogy and Morphology of Ureolytic Bio-Cementation

   https://doi.org/10.1061/9780784482834.010  

   Burdalski, Robert J. ; Gomez, Michael G. ( February 2020 , GeoCongress 2020)

   Numerous laboratory studies in the past decade have demonstrated the ability of microbially induced calcite precipitation (MICP), a bio-mediated soil improvement method, to favorably transform a soil’s engineering properties including increased shear strength and stiffness with reductions in hydraulic conductivity and porosity. Despite significant advances in treatment application techniques and characterization of post-treatment engineering properties, relationships between biogeochemical conditions during precipitation and post-treatment material properties have remained poorly understood. Bacterial augmentation, stimulation, and cementation treatments can vary dramatically in their chemical constituents, concentrations, and ratios between researchers, with specific formulas oftentimes perpetuating despite limited understanding of their engineering implications. Inmore »this study, small-scale batch experiments were used to systematically investigate how biogeochemical conditions during precipitate synthesis may influence resulting bio-cementation and related material engineering behaviors. Aqueous solution chemistry was monitored in time to better understand the relationship between the kinetics of ureolysis and calcium carbonate precipitation, and resulting precipitates. Following all experiments, precipitates were evaluated using x-ray diffraction and scanning electron microscopy to characterize mineralogy and morphology. Results obtained from these investigations are expected to help identify the primary chemical and biological factors during synthesis that may control bio-cementation material properties and« less
5. The evolution of snow bedforms in the Colorado Front Range and the processes that shape them

   https://doi.org/10.5194/tc-13-1267-2019  

   Kochanski, Kelly ; Anderson, Robert S. ; Tucker, Gregory E. ( January 2019 , The Cryosphere)

   Abstract. When wind blows over dry snow, the snow surface self-organizesinto bedforms such as dunes, ripples, snow waves, and sastrugi. Thesebedforms govern the interaction between wind, heat, and the snowpack, butthus far they have attracted few scientific studies.We present the first time-lapse documentation of snow bedform movement and evolution, as part of a series of detailed observations of snow bedform movement in the Colorado Front Range.We show examples of the movement of snow ripples, snow waves, barchan dunes,snow steps, and sastrugi. We also introduce a previously undocumentedbedform: the stealth dune. These observations show that (1) snow dunesaccelerate minute-by-minute in response tomore »gusts, (2) sastrugi and snow stepspresent steep edges to the wind and migrate downwind as those edges erode,(3) snow waves and dunes deposit layers of cohesive snow in their wake, and(4) bedforms evolve along complex cyclic trajectories. These observationsprovide the basis for new conceptual models of bedform evolution, based onthe relative fluxes of snowfall, aeolian transport, erosion, and snowsintering across and into the surface. We find that many snow bedforms aregenerated by complex interactions between these processes. The prototypicalexample is the snow wave, in which deposition, sintering, and erosion occurin transverse stripes across the snowscape.« less