Headrace Tunnel—Leak Detection - Case Study

This hydropower plant in Central America is a vital part of its country’s infrastructure, supplying 18% of the country’s power.

THE PROBLEM: HEADRACE TUNNEL LEAKAGE

Our client observed their 4km headrace tunnel had major leakage problems. In an attempt to better understand the problem, the client underwent several inspections which ultimately proved unsuccessful. Complicating matters even further was the fact that it cost the client about $1M USD for every day the plant was out of service, so any inspection needed to be done quickly.

THE SOLUTION: WILLOWSTICK’S LEAK DETECTION TECHNOLOGY

Willowstick performed a leak detection investigation from inside the tunnel, using an ROV and highly sensitive instrument. By injecting electric current into the tunnel we were able to measure the anomalies inside and determine the most likely leak locations. The low gradient (macro-scale) anomalies were most likely caused by geologic changes on the outside of the tunnel, and the high gradient (micro-scale) anomalies indicate the potential leakage from the tunnel [see following page for the results]. The results showed two areas with several high gradient anomalies that are the most probable leak locations; one of which was confirmed visually using the ROV. Using this approach, we were able to quickly (less than 48 hours) identify several potential leak locations, while also helping the client prioritize which leaks needed remediation first.

THE BENEFIT: SAVING TIME AND MONEY

With this information, the client is able to target their remediation in the highest priority areas, saving time and money by eliminating guess work.