Reclamation Information Sharing Environment (RISE)

The presence of voids behind or below a structure can limit operations at best and at worst be a precursor to failure. Voids could lead to hydraulic jacking, ground instability, and a roofed path for internal erosion processes. Any and all of these conditions could result in a failure, as seen recently at the Fort Laramie tunnel or the Oroville Dam spillway. This report is intended to provide a high-level overview of the topics as they relate directly to the problem of void formation near spillways, conduits, canals, tunnels, and siphons. A series of questions aimed at guiding the investigator towards structures (inventory-wide) and areas (structure-specific) most likely to have voids is provided to streamline detection efficiency. Subsequent reports build on this work by detailing detection methods and repair techniques with this series of questions used to optimize efficiency.