In order to meet the WWII demand for airfields in the South East of England a massive build programme was started but the chances of these airfields falling into the hands of an invading German Army and Luftwaffe was not lost on the planners.
To mitigate the risk all airfields within 1 hours drive of the coast were to have specific denial arrangements. These ranged from simple instructions on how to smash a fuel valve with a conveniently located hammer to detailed instructions on emptying fuel tanks and destroying electrical equipment.
A method was also sought to deny the runway to enemy gliders and transport aircraft and so the Canadian Pipe Mine was devised by the 1st Canadian Tunnelling Company. 50-70mm steel pipes were inserted into the ground using hydraulic pipe pushing equipment and laid in a criss cross pattern about 6ft under the surface. They were subsequently filled with explosives, usually a blasting gelignite called ‘Polar Blasting Gelignite’ which was very powerful.
They were also called McNaughton tTubes after the GOC of 1 Canadian Division who according to his biographer got the idea for using hydraulic rams from bootleggers who used the method for creating an offsite distribution point for their whiskey!
Only 9 airfields were identified for mining initially but this rose to include other locations, by the end of 1942, after the threat of invasion had receded, 30 locations were mined, not all of them airfields. It is estimated that over 40,000ft of pipe mines were installed.
During the war some of the pipe mines were made safe and removed because of the deterioration of the explosive filler but most were left in situ. After the war Canadian engineers were tasked with removal but it seems from reading different sources that records were incomplete and some doubt exists whether the clearance activity was completed. Additional clearance efforts were made, one that resulted in the death of Ukrainian worker at one of the locations.
Since then a number have been cleared by the Royal Engineers and private contractors such as Ramora, click here to view a gallery of images from 49 EOD Squadron Royal Engineers, many Canadian Pipe Mines on display.
Operation CRABSTICK was the name given to the effort to clear WWII pipe mines, a recent Freedom of Information Act release provided a little more information.
20 pipe mines were discovered during construction work in 2006 at HMS Daedelus in Lee-on-Solent requiring a 5 week operation by 33 Engineer Regiment to clear them that also saw the first deployment of the QinetiQ Appliqué Robotic Kit (ARK) a system designed to allow remote control of a standard JCB type backhoe loader. ARK can be installed in less than 12 hours and enables remote control up to 1km away using an encrypted data link.
A more recent example was cleared by Ramora from the BAE site on the Isle of White, formerly RAF Somerton.
Clearly, the post war clearance operation did not clear them all and who knows how are are still in the ground!