<p><p><div><img class="aligncenter wp-image-3330 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of Route 22 project stone column installation. Large crane has vibrator partially inserted into the ground as the stone column is being constructed." width="1259" height="890" /></div><h2>Project Summary/Scope:</h2>Stone columns were used to stabilize a 220-foot long slope along New York Route 22 near Wadhams, NY.</p><p>Subsurface conditions: 3-meter thick layer of silty clay overlying a 3- to 6-meter layer of over-consolidated, soft, silty clay. This clay layer is underlain by a layer of silty gravel in which artesian groundwater conditions were encountered. The liquidity index and activity of the clay were 1.0 and 0.5, respectively.</p><p>A stabilizing berm, shear key, and stone columns were considered. Berm treatment would require additional right-of-way in a wetland area, and the shear key would require extensive excavation. Stone columns installed by the dry, bottom-feed method were found to be the most technically feasible, environmentally acceptable, and economic solution. The stone columns were installed through the soft clays into the gravel layer to intercept the slip plane near the gravel/clay interface at a depth of 4.8 meters.<br><h2>Alternate Technologies:</h2>A stabilizing berm, shear key, and stone columns were considered.<br><h2>Performance Monitoring:</h2>Prior to construction, slope movement was measured at approximately 0.08 mm per day. During installation, the total movement was 3.3 mm. Eight years after project completion, little to no additional movement had been recorded.<br><h2>Project Technical Paper:</h2>Sung, J.T. and Ramsey, I.S. (1988). “Slope Stabilization by Stone at Wadhams, NY,” Report by Soils Mechanics Bureau, New York DOT, Albany, NY.</p><p><em>Also see</em></p><p>Elias, V., Welsh, J., Warren, J., Lukas, R., Collin, J. G., and Berg, R. R. (2006a). Ground Improvement Methods - Volume I. NHI-06-020.<br><h2>Data Case History Prepared:</h2>November, 2012</p></p>