A hydroelectric plant on a major river sought to install a new fish ladder for an endangered species. Construction of the ladder required founding the concrete walls directly on bedrock. However, because of years of sedimentation above and below the dam, the thickness of the sediment and bedrock conditions were unknown. RETTEW was hired to determine the impact of the sedimentation before construction began.

Using multibeam sonar and marine seismic refraction techniques to provide the highest level of precision for the project, RETTEW provided detailed mapping and stratigraphic profiles so the client could accurately design plans for the fish ladder. These marine survey techniques enabled the client to understand site conditions without assumptions and the project experienced no delays or extra costs during construction. The cost savings were valuable to the client because the fish ladder does not generate revenue, but it is beneficial for the fish and the environment.