U.K. sends National Archives underground.

• Author: Swartz, Nikki
• Position: Up front: news, trends & analysis

The United Kingdom's National Archives at Kew has begun the process of moving its records 150 meters (about 492 feet) below ground--from its current location at Hayes, Middlesex, to a salt mine in Winsford, Chesire.

The National Archives currently stores about 25 km (82,000 fret) of records at the Ministry of Defence site at Hayes. Kew has a total capacity of 161 km (528,215 feet) and about 145 km (475,722 feet) of that is full already. The office takes in about 2 km (6,562 feet) of records annually, so off site storage is the only way forward, says David Thomas, director of government and archival services. He says storage is needed for about 25 km of records, which meets the environmental standards for the Storage of Archival Documents (BS 5454).

The first shaft of the salt mine was sunk in 1844 and is the oldest working pit in the United Kingdom. It now has more than 100 miles of underground roadways and produces rock salt, which is commonly used for deicing streets and sidewalks during the winter months.

According to Thomas, in World War II the mine was considered by the Public Records Office (PRO) as a place to re-house records during the V1 raids. It was rejected only because the British government, which was using it to store emergency food supplies, had installed a sprinkler system to protect valuable supplies against fire. The system used salt water, which was considered unacceptable for records. Later, after the sprinkler system and food were long gone, the mine was selected as a place for storing public records from Cheshire Record Office in 1998.

The mine offers a storage facility boasting low energy requirements, natural conditions that are a constant 14 degrees Celsius (57 degrees Fahrenheit) and 62 percent relative humidity. A small amount of dehumidification will adjust the...