Stephen England, U.S. Army Corps of Engineers hydraulic engineer, uses sonar equipment to gauge the depth of a bridge’s foundation below water May, 30, 2013, at Joint Base McGuire-Dix-Lakehurst, N.J. Gauging the depth of the foundation can be cross analyzed with previous recordings to determine if the foundation has shifted over time. (U.S. Air Force photo by Airman Sean M. Crowe/Released)