Failure is never an option for critical projects. GeoSonics/Vibra-Tech helped the U.S. Army Corps of Engineers maintain critical dam integrity.
Mississippi River flooding during the spring of 2008 near Canton, Missouri caused a breach in the levees near Lock & Dam 20 at Meyer, Illinois. As governing agency, the U.S. Army Corps of Engineers responded. They needed to repair the levee immediately to control the river and avert further damage to the downstream communities and further erosion of the levee area. The actual repair required the removal of a portion of the service bridge for the levee, then installation of a series of sheet piles for the construction of a storage area adjacent to the east end of the dam. When driving piling or conducting high-level vibration work adjacent to earthen structures, there is a strong potential for soil consolidation, which can have effects on the stability of the dam, embankments and adjacent structures. Soil slippage may induce further failure or cause weakened soils to be further damaged. Normal limits on ground vibration are not sufficient to safeguard such soils.
GeoSonics/Vibra-Tech was retained by the pile-driving subcontractor to determine limitations for the adjacent structures. The integrity of these structures was key to determining at what point demolition and pile-driving activities could cause damage. Additionally, limits on the construction work vary, so specific limits had to be generated for each operation. Our structural dynamic engineering expertise and services helped determine these limits. Based on the site soil boring logs, pile driver hammer energy, and integrity of the structures, GeoSonics/Vibra-Tech developed a vibration monitoring program to be implemented during construction activities. We then performed continuous vibration monitoring during the project to ensure that levels were maintained within the special limits. As required by the U.S. Army Corps of Engineers, the repair was completed without any effects on the integrity of adjacent structures.