Senior Airman Omar Portillo, 28th Civil Engineer Squadron structural technician, uses grout to fill space between tiles on a bathroom floor in the 28th CES operations building on Ellsworth Air Force Base, S.D., Feb. 21, 2013. Structural technicians like Portillo complete rojects like this as a component of their career field program training. (U.S. Air Force photo by Airman 1st Class Kate Thornton-Maurer/Released)