Airman 1st Class Clint Hubkey, 28th Civil Engineer Squadron heating, ventilation, and air conditioning technician, pumps glycol into a closed water system during winterization activities at Ellsworth Air Force Base, S.D., Oct. 16, 2012. The HVAC shop ensures that more than 320 buildings on base are prepared for harsh winter weather conditions. (U.S. Air Force photo by Airman 1st Class Alystria Maurer/Released)