AmerenUE's Callaway County Nuclear Power Plant was performing a feasibility study for its Construction and Operating License Application (COLA). As part of this permitting process, Rizzo Associates, Inc. selected Terracon to provide geotechnical borings and limited geotechnical engineering on this project. Over 80 borings ranging from depths of 41 to 350 feet (averaged 110 feet) were performed. Drilling was performed over four months using 9 drill rigs and 8 drill crews. The drilling operation was nearly continuous (7 days per week) with rotating 10 day on/4 day off shifts. Weather during the 4-month-period was harsh with over six weeks of weather with lows near zero and highs near 15 to 20 degrees Fahrenheit.