Safety board: Fatal Diemen explosion an avoidable accident

Damage caused by the explosion in an apartment building in Diemen (Picture: Dutch Safety Board). (Damage caused by the explosion in an apartment building in Diemen (Picture: Dutch Safety Board))

The Dutch Safety Board has ruled that the explosion in an apartment building in Diemen on September 4th last year was an avoidable accident, according to their report on the incident. Two people died in the explosion and 15 others were injured. The explosion caused a huge amount of material damage. More than 200 people were displaced and 32 apartments were so severely damaged that they were uninhabitable for months.

The explosion happened in the apartment building De Beukenhorst while contractors were working on rennovations. According to the Safety Board, workmen were attempting to remove an iron pipe with a crane, not knowing that the pipe contained an operative gas line. The crane caused a connecting unit of the gas pipe to detach and gas escaped and flowed into the apartment building, accumulating in various spaces o the ground floor and then ignited.

During the investigation, the Safety Board concluded that there were three main causes of the accident. The first is that insufficient information was shared about the presence of underground pipes while the excavation work was being prepared. The contractor did request this information, but the information was not sufficiently collected, specifically with regards to the house service connections.

The second cause relates to the actual execution of the work. According to the Board, not all aspects of the designated guidelines on prudent excavation practices were adhered to. In particular, the contractor did not submit notification of excavation shortly before starting the work to ensure that they had the latest information about the underground pipes. The Board also questions the contractor's decision to remove an unknown pipe without knowing what type of pipe it was.

The Safety Board finally also concluded that the way in which the involved parties acted after the gas leak was reported, had an impact on the consequences of the explosion that followed. When the gas leak was reported, the staff member of the Fault Clearing Service did not assess the report as "very urgent". No further action was taken on the site itself and the fire department was not alerted. According to the Board, this can be explained by the fact that the danger was hidden from view and those involved did not realize how dangerous the situation was.

The Safety Board recommends that the information exchange on house service connection in the gas network be improved, that sector associations in excavation promote strict adherence to the Prudent Excavation Practices guidelines and that network operators should improve the assessment of dangerous situations when excavation damage to gas pipes is reported.

Network operator Liander has received the Dutch Safety Board's report. The company calls it a "good report" and agrees with the recommendations. "We already have a strict protocol, but we're going to go through it properly. Because dealing with gas reports should never be routine, not even if you have a professional on the line", a spokesperson for Liander said to AT5.