<p><p><h2>Commentary</h2>There have been very few field applications of this technology to date. Because of this, there is insufficient data available to present detailed cost information.<br><h2>Conceptual Cost Estimating Tool</h2>No estimating tool is provided for this technology.</p><p>&nbsp;</p></p>

<p><p><figure id='attachment_2531' style='max-width:1183px' class='caption aligncenter'><img class="wp-image-2531 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Diagram of various bio-treatments in levee system including bio-reinforcement preventing erosion, bio-mineralization stabilizing a slope, bio-film preventing groundwater seepage, bio-mineralization immobilizing car

<p><p><strong>Reference(s):</strong></p><p><em>DeJong et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>The compression wave corresponds to compression and dilation of material parallel to the direction of propagation. Compression waves can propagate through solids and fluids effectively, and is affected by bulk modulus, degree of saturation, and porosity.

<p><p><strong>Reference(s):</strong></p><p><em>DeJong et al. (2006)<br>Perkins et al. (2000)</em></p><p><strong>Method Summary</strong></p><p>The designer needs to prepare specimens by using bio-treated soils. The samples also need to be compacted in the laboratory, and undisturbed samples from the field are best, if available.

<p><p><strong>Reference(s):</strong></p><p><em>Ivanov and Chu (2008)</em></p><p><strong>Method Summary</strong></p><p>Proper microorganisms are needed for effective bio-treatment of soils. The microorganism physiological classification method is used in quality assurance. The efficiency of bio‑stabilization is related to microorganism oxygen requirements, energy generation, cell structure, growing conditions, etc.

<p><p><strong>Reference(s):</strong></p><p><em>Perkins et al. (2000)</em></p><p><strong>Method Summary.</strong></p><p>Oedometer experiments were performed on specimens to estimate the effects of bio-film on one‑dimensional compression and secondary compression behavior. After applying vertical stresses ranging from 15 to 4,500 kPa to a specimen, the displacement is measured by a dial gage. The oedometer experiments consist of two types.

<p><p><strong>Reference(s):</strong></p><p><em>DeJong et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>Resistivity can supply a measure of the voltage potential gradient through a soil matrix when an electrical current is applied across a soil specimen. Volume fractions of particles and voids, particle composition, soil particle specific surface area, and degree of saturation can affect measurement of resistivity.

<p><p><strong>Reference(s):</strong></p><p><em>DeJong et al. (2006)<br>Neumeier (1999)</em></p><p><strong>Method Summary</strong></p><p>A micro‑scale investigation can observe the characteristics, degree of bonding between particles, and compositional nature of cementing agents directly.

<p><p><strong>Reference(s):</strong></p><p><em>DeJong et al. (2006)<br>DeJong et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>Shear wave velocity can be readily measured with bender elements in the laboratory. In a specific study, a 20 V sine wave was applied at 10 kHz frequency to a parallel transmitting element and the received signal was detected by a series bender element.

<p><p><strong>Reference(s):</strong></p><p><em>Whiffin et al. (2007)</em></p><p><strong>Method Summary</strong></p><p>Microorganisms in soil specimens need nutrients to grow. Urease is a very important nutrient for bacteria. When no calcium ions exist, urease activity can be determined by a conductivity method.