In February 2020, Explosive Clearance Group started the approach work around the runway at Gilze Rijen Airport as part of the Replace Aircraft Braking System project of the Government Property Agency.

Gilze Rijen, once a large Fliegerhorst, was for many years the accommodation for the so-called KGs (Kampfgeschwaders: squadrons with bombers). Also fighter planes and night fighters made eager use of the Brabant airfield. Therefore Gilze-Rijen airfield has been the target of the Allies more than once.

Fliegerhorst is the German name for a large air force base. The designation originated before the Second World War. It was the designation of a German military airfield with the status of a self-sufficient extended main airfield.

Because the project area is suspected of containing Conventional Explosives (CE), Heijmans Bodem started by carrying out non-real-time detection. During the detection, several suspect objects were detected. And so it happened that ECG, under the leadership of senior OCE expert Henk Kloosterboer, approached various suspect objects on the military airfield. The flight movements of the Royal Netherlands Air Force also had to be able to continue unhindered during the search activities. A complicated assignment that, thanks to the efforts and close cooperation of the State Property Agency with ECG, was a success.

The approaches resulted in finds such as metal Allied flight strips, waste and ammunition items. For example, 3 British Target Indicators (TI) of 250 lbs and also an American 1000 lbs aerial bomb with a tail and a nose tube (ignition) were found. However, all alarm bells went off when a British 500 lbs brisant bomb with a sensitive detonator was identified. This aerial bomb was located on the most unfavourable location on the airfield because of the many surrounding vital Defence cables.

Sensitive detonator

The 500 lbs aerial bomb found was equipped with a broken tail gun (mechanism with a detonator), the No.37 with an anti-detonator. The detonator works by pulverising a glass ampoule with a rotating impeller, after which a chemical substance is released and dissolves a celluloid disc. Once this disc has been sufficiently damaged, a pre-tensioned firing pin spring can strike a percussion cap, initiating detonation.

Together with the State Property Agency, the EODD, Defence, various stakeholders and ECG, a solution was sought that was as efficient and safe as possible. The nature of the ammunition that was found, the location between the vital cables of the Ministry of Defence, the planned flight movements and the 'Swift Blade' event that was taking place at the time led to the application of an appropriate and rapid method. This solution turned out to be a 'Terp construction'. A tried and tested method used by ECG more often.

A Mound construction is a special, custom-built construction in which the EODD can ultimately carry out its work with extra security. It is a construction that holds back the bomb fragments and directs the resulting air pressure in a controlled manner in a safe direction.

The bomb disposal finally took place during the following weekend, when the fewest aircraft movements took place at the airport. From Friday to Sunday morning, work continued diligently to build up the protective Terp. As agreed, everything was ready in time and on Sunday morning, the EODD specialists were able to successfully dismantle the detonators in the protective structure in complete safety. This feat was performed by the military with the help of water cutting. Finally, the EODD removed the bomb bodies and destroyed them in a controlled manner on the Oirschotse Heide. After everyone had left, ECG dismantled the mound and the Air Force was able to use its runway again on Monday.

"The total package of work was carried out to the full satisfaction of the client, the State Property Agency," said Mr Kerkhoven, project manager of the State Property Agency.