Carl Piper, 319th Civil Engineer Squadron contractor, uses a flapper tool to help put out part of a 60-acre controlled fire May 7, 2013, in the area across from the main gate of Grand Forks Air Force Base, N.D. The purpose of the prescribed burn was to rid the site of woody encroachment, regulate growing weeds and to conserve the habitat. (U.S. Air Force photo/Airman 1st Class Xavier Navarro)