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Client: Army Corp of Engineers
Definition: Spillway Investigation
Location: West Yankton, South Dakota

This was the largest assessment ever at Gavin’s Point Dam. Our goal was to provide information to the Army Corps of Engineers on the “apron” – or concrete slab that serves as the spillway floor. The work was needed not only because of the age of the 55-year old structure, but also because the Flood of 2011 put it to the test as it passed 150,000 to 160,000 cfs for 65 days during the flood. The investigation required 40 holes drilled in the concrete to assess the gravel base beneath. All of this took place during the coldest weather imaginable. Windy weather held up drilling several times, as did ice on the spillway gates. Even though there were weather delays, the investigation was completed on time with no injuries or incidents.