Earthen dam leak detection system

SafetyNet™ is a tool for enhancing dam safety based on the latest innovations in geophysical methods. Founded on the simple but well-proven principles of electrical current flow in moist ground, SafetyNet™ adds significant improvements to provide an effective and low-cost means of accurately mapping and monitoring the movement of water within and through the body and foundation of embankment structures. This virtual "window" provides superior data for the analysis and management of the risks associated with embankment dams, consequently reducing the costs associated with those tasks. It also provides superior early warning capabilities, thus controlling the risks and costs resulting from dam failures - eliminating them in most cases and minimizing them in the rest.

The basic principle underlying SafetyNet™ is simple: Electrical current flow through earthen material is directly proportional to water content and precise mapping of that flow yields proportionally precise mapping of relative saturation levels. But traditional DC resistivity data collection and processing methods provide relatively poor resolution and thus not the desired precision. To overcome that, Dr. James B. Fink (founder and president of hydroGEOPHYSICS, Inc.) developed a series of data processing algorithms that, when combined with appropriate data density, precise data measurement, and precise x,y,z source point location, result in a virtual high-resolution image of the subsurface. Using those same parameters, a similar method (high resolution resistivity or HRR) that led to the design of SafetyNet™ has already proven extremely effective in mapping liquid distribution (particularly leach solutions) within heaps and dumps; mapping leakage beneath damaged liners; and tracking wetting fronts of percolating liquids. The nature of problems presented by seepage and piping in embankment dams are nearly identical to those applications and so suggest that SafetyNet™ would be similarly effective there as well.

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To provide the risk analysis and management needed for embankment dams, however, SafetyNet™ needed to go beyond the static, linear cross-sections typically provided by older methods. To accomplish this, SafetyNet™ employs a two-dimensional grid, or "net", of small electrodes implanted on the surface of the structure that may be sized to provide data over all or any portion of the structure and its foundation. The grid is then connected to a PC based data collection, storage, and processing unit through multi-conductor cables. This adds the important capability of generating not only cross-sections beneath any line of the grid but also a three-dimensional surface that accurately reflects the phreatic surface beneath the areal extent of the grid.

Please view an example of leak detection results that can be generated with SafetyNet™.