The Yelm Hydroelectric Project provides reliable clean energy to the City of Centralia, Washington. A run-of-the-river concrete ogee dam diverts water from the Nisqually River into a nine-mile canal before it falls 200 feet into the powerhouse.
In 1996, flooding in the Nisqually River washed out the canal’s earth-fill embankments, originally built in the late 1920s. The City of Centralia contracted with GeoEngineers to engineer repairs to the embankments, and we have provided dam safety consultation for the project on a regular basis ever since.
Since that time, GeoEngineers has guided the city through the Federal Energy Regulatory Commission (FERC) regulatory process and helped the facility maintain their licensure requirements. GeoEngineers’ geotechnical, geologic and hydrological experts have completed ongoing evaluation of project safety and provided recommendations for improvements to infrastructure, instrumentation and monitoring. In order to define inundation areas and potential threats to public safety GeoEngineers also completed one- and two-dimensional breach analyses.
During the long and successful relationship with the City of Centralia, GeoEngineers has performed regular safety evaluations and recommended a progression of improvements to address potential areas of concern. Dam safety is an ongoing challenge that is never complete, but GeoEngineers’ team can equip dam owners like the City of Centralia with the information they need to spend their resources effectively and make risk-informed decisions for improvements to project safety.