History's Greatest Fortifications- Cheyenne Mountain

First envisioned by General Earl Partridge in 1956, Cheyenne Mountain is the greatest Cold War- era military fortification in the world. In a lot of ways, it is the greatest fortification ever built.

Cheyenne Mountain houses the Cheyenne Mountain Operations Center and Cheyenne Mountain Directorate. Their function is to collect real time data from a worldwide system of satellites, radar, and other types of sensors . Operations are conducted year-round in the Air Warning Center, Missile Correlation Center, Operational Intelligence Watch, Systems Center, Weather Center, and the Command Center. Cheyenne Mountain is unique in several ways. It is housed 2,000 feet into a mountain, and is also a joint and binational military organization comprising over 200 men and women from the United States Air Force, Army, Navy and Marine Corps, Coast Guard and The Canadian Army and Air Forces.

The site was chosen for several reasons: it had a low risk of earthquakes, it was centrally located, also nearby there was a major interstate, Fort Carson, and the Air Force Academy. Excavation for the facility began in May 1961, and was completed in May 1964. The NORAD Combat Operations Center became operational on February 6, 1966, and operations were transferred from Ent Air Force Base on April 20, 1966.

Today, Cheyenne Mountain is also home to elements of the North American Aerospace Defense Command (NORAD), the U.S. Strategic Command, the U.S. Air Force Space Command, and the U.S. Northern Command (USNORTHCOM). The hardened Combat Operations Center (COC) was originally intended to provide a 70% probability of continuing to function if a five megaton nuclear blast detonated within three miles away, but upgraded was ultimately built to withstand a blast within 1.5 nautical miles. It was also designed to be self-sufficient for brief periods, have backup communications and television intercom with related commands, house personnel during an emergency, and protect staff against fallout and biological and chemical warfare.

The facility was originally intended to be an operations center to provide command and control in support of the air defense mission against the nuclear armed bombers from the USSR. Cheyenne Mountain took on new duties as the intercontinental ballistic missile (ICBM) became the main form of nuclear weapon delivery in the late 1960s. NORAD developed warning and assessment systems that kept watch over the Soviet air bases and missile fields and could detect a launch and notify the Pentagon and the President within minutes.

The Cheyenne Mountain Upgrade was instituted in 1989 to integrate new technologies to the complex. The CMU contained several major subsystems: Granite Sentry, the Communications System Segment Replacement, the Survivable Communications Integration System , the Space Defense Operations Center 4, and the Command and Control Processing and Display System Replacement. The Air Force also maintained the Alternate Missile Warning Center at Offut AFB to serve as a independent, fully functional backup program.

The Operations Center provided theater ballistic missile warnings during The Persian Gulf War, when Defense Support Program satellites looked for the heat from missile and booster plumes and provided warning to civilians and troops in Israel and Saudi Arabia.

Design

The Operations Center of Cheyenne Mountain is along one side of the main tunnel bored nine tenths of a mile through the mountain. The center was designed to withstand up to a 30 megaton blast within 1-nautical-mile. It is sealed by 25 ton blast doors and the tunnel was designed to deflect the massive blast wave past the Operations Center. Behind the doors, the main complex is a 4.5 acre grid of chambers and tunnels. The main excavation consists of three chambers 45 feet wide, 60 feet high, and 588 feet long, intersected by four chambers 32 feet wide, 56 feet high and 335 feet long. Fifteen freestanding buildings up to three stories tall make up the main excavation. The buildings do not have any contact with the 2000 foot thick granite walls. The buildings have an outer shell of low carbon steel and along with the metal tunnels that connect them, serve to dampen the effects of an electromagnetic pulse (EMP).

There are blast valves to mitigate the effects of an attack installed on the air intakes and exhaust as well as water, fuel, and sewer lines. Sensors at the North and South Portal entrances will detect overpressure waves from a nuclear explosion, causing the valves to close and protect the complex. The buildings in the complex are mounted on 1,319 steel springs, each weighing 1,000 pounds. The springs allow each building to move 12 inches in any one direction and reduce damage from nuclear blast effects or earthquakes.

To protect against nuclear fallout and chemical and biological weapons, incoming air can be filtered through a system of filters. Fresh air intakes are mainly from the south portal access which is 17.5 feet high and 15 feet wide.

Cheyenne Mountain was intended to be self-sufficient and there are four excavated reservoirs with a capacity of 1.5 million US gallons of water deep in the complex for the base water supply. Three serve as industrial reservoirs and the remaining one is the complex’s primary domestic water source. They are so large that workers sometimes cross them in rowboats. More than 40,000 gallons are in the reservoirs at any given time. While primary electrical power comes from Colorado Springs in daily operations, there are six 1750 kilowatt generators for a backup. There is also a large dining facility, a medical facility with dental office, pharmacy, To complete the support functions, there are also two physical fitness centers a small base PX.

In 2006, NORAD chose to move the bulk of Cheyenne Mountain's operations to nearby Peterson AFB in order to reduce duplication of function between the two sites. NORAD has since renamed the facility as the Cheyenne Mountain Directorate, and placed the operations center on “warm stand-by,” meaning that the facility will be maintained and ready for use on short notice as necessary, but not used on a daily basis.