An important part of Britain’s wartime heritage lies hidden on the Hollybank site, off Muswell Hill. A WW2 communal air-raid shelter was built below trees and shrubbery near the rear gardens of Cranmore Way.
Our drain engineers were sent there to measure the shelter and record what they found. A CCTV survey was performed however this was no ordinary survey. It was a low oxygen (hypoxic) environment and therefore needed full air-lined entry equipment.
Normal air is a mixture of oxygen and nitrogen, together with small quantities of carbon dioxide and other gases. When the oxygen content is lower than normal air, e.g. when it is intentionally lowered for special applications, the resulting gas is called hypoxic air or low oxygen air.
The conclusion of this job was that the entrance tunnels were blocked with barrels, these will need to be cleared before further work commences. Once back at the office a plan will be drawn up and a full report written to send to the client.