<p><p><strong>References:<br></strong><em>Al-Homoud and Degen (2006)<br>Ashford et al. (2000)<br>Lopez and Shao (2007)<br>Mackiewicz and Camp (2007)<br>Schaefer et al. (2016)</em></p><p><strong>Method Summary</strong></p><p>Installation of stone columns in clean to silty sands (less than 15% fines) can densify the surrounding soil resulting in higher strengths and densities. Cone Penetration Tests (CPTs) may be used to verify soil improvement as indicated by the CPT penetration resistance of the soil before and after stone column installation. It is important that locations be identical before and after treatment to provide an accurate depiction of the level of improvement. Though stone columns may increase the strength of some cohesive soils, several months or more may be required before the beneficial effect is observed (Barksdale and Bachus 1983a). Therefore, stone columns are not considered an effective means for increasing the strength of cohesive soils and function primarily as reinforcing elements. CPTs are not typically performed when stone columns are installed in cohesive soils.</p><p><strong>Accuracy and Precision</strong></p><p>When coupled with local experience and judgment, the CPT can provide accurate and precise information.</p><p><strong>Adequacy of Coverage</strong></p><p>The CPT allows continuous testing of a soil profile.</p><p><strong>Implementation Requirements </strong></p><p>The CPT is widely used and the equipment is typically readily available.</p><p><strong>General Comments</strong></p><p>The CPT provides correlations to soil strength, making it useful for ensuring quality for slope stabilization, support of structures, support of embankments, settlement reduction, liquefaction mitigation, and prevention of lateral spreading.</p></p>