In the 1950s and 1960s two tunnels were constructed next to a former chemical processing plant, the Plutonium Uranium Extraction Plant, or PUREX, located in an industrial area near the center of the Hanford Site called the 200 East Area. The tunnels were constructed of wood and concrete and covered with approximately 8 feet of soil. The tunnels were constructed to hold rail cars that were loaded with contaminated equipment and moved into the tunnels during the Cold War.