Wanapum Dam Repairs GPR Scans Vantage, WA


In response to cracks within the Wanapam Dam structure, White Shield provided scans using GPR (Ground Penetrating Radar) to detect the scope and range of cracks and leaks. Deliverables included markings on ceiling, walls, and floors to depict locations of scanned anomalies found. Scans were performed by a 2 man crew and took place during 10 hour days, between 6 – 8 areas scanned per day, on scaffolding and ladders reaching up to the 10’ ceiling height. Additional scans were performed periodically during repair efforts to find conduit and rebar within the concrete structure.

The crack was discovered in February, and PUD officials immediately dropped the water level to relieve pressure on the cracked spot. Fixing the underlying design problem involves installing 35 cables (cable bundles) across the entire face of the dam, adding up to three cables per pillar. The Federal Energy Regulatory Commission, which oversees the Columbia River hydropower system, is mandating the crack be fixed and each pillar to have at least one cable installed before the PUD will be allowed to raise the water. While trying to find out what caused the crack, PUD officials discovered an error in the original design calculations, which meant repairs were required across the entire structure. As of Nov. 7, the PUD drilled all the pilot holes for the cables, and 13 cables have been installed, meeting FERC requirements, and the anchor bars in the damaged portion are being installed as well.