2022 – Resonance Acoustic Profiling (RAP) – A helpful and complimentary tool for mapping seepage through, beneath and around dams

Dr. Andy Hughes – Managing Director, Dams& Reservoirs Ltd, United Kingdom
Mitchell Green – Geologist/Project Mgr, Willowstick Tech. LLC, USA
Ryan Blanchard – Senior Vice President, Willowstick Tech. LLC, USA
Mike Jessop – Chief Geophysicist , Willowstick Tech. LLC, USA

Willowstick has successfully employed a new Resonance Acoustic Profiling (RAP) method to improve seepage characterization through, beneath, and around dams. RAP is a passive seismic method that detects zones of higher permeability in the foundation and fill materials of a dam. Just as the ocean has tides, the earth’s crust experiences daily “Earth Tides” and is constantly in motion. Continual motion produces resonance signals that can be measured, interpreted, and modeled to identify zones of higher permeability within the dam fill and bedrock foundation. The RAP results are analyzed in conjunction with traditional Willowstick Method results to better characterize seepage flow paths. Willowstick has effectively utilized the RAP method on nine highly successful seepage investigations at dam sites; however, the focus will be on two case studies in Canada and the United States.