Entry page » Investigation reports » Other accidents » Investigation reports by year » 2006 » B3/2006Y Accident at an excavation site in Espoo on 24 April 2006

B3/2006Y Accident at an excavation site in Espoo on 24 April 2006

A semi-detached house was being built in Friisilä, Espoo. The construction work was in its early stages, and excavation work for the foundation and public utility services was in progress. The site consisted mainly of open rock, which was meant to be removed by quarrying approximately 1,400 cubic metres. Over the preceding month, approximately 70 explosions had been performed, and the plan was to carry out approximately five more. The site was in the middle of a residential area, so the rock was quarried in small fields.

On Monday, 24 April 2006, one explosion was carried out at 7:57 a.m., after which the holer continued to drill new holes with the drill carriage. The charger and charger’s assistant prepared the next field and moved the explosives, placed in boxes, next to the driveway, approximately 5–6 metres from the field. A blasted rock transportation vehicle (lorry) arrived on the site to transport the quarried rock material away. The lorry driver backed along the driveway near the boxes of explosives, and an excavator began loading rocks on the platform. At the end of the loading, a rock was left precariously atop other rocks on the platform, then slid over the side of the platform and fell on the explosives. This resulted in a heavy explosion, causing the lorry, drill carriage, and compressor to catch fire. The emergency centre received several emergency calls regarding the accident, and, in total, six rescue service units and 10 medical rescue service units were called to the site. Police were responsible for isolating the area and clearing away the explosives.

The rescue operations of both rescue services and medical services were successful, despite the fact that initially, given the seriousness of the accident, too few resources were called in. Rescue operations were further hindered by the detonators exploding in the ground because of the fire, but, as a whole, the situation was handled well.

The direct cause of the accident was an approximately 400-kg rock falling on boxes of dynamite during loading of quarried rock material. A problem was created by the loading taking place in the same narrow location in which the site's explosives were kept. The site was designed inadequately, and managerial decision-making relationships were unclear. The implementation of blasting work was based on experience and oral instructions and agreements. Methodicalness is emphasised in regulations concerning blasting work, but work site visits and other accidents indicate that, in practice, the intended methodicalness and drafting of appropriate plans has not been implemented on small work sites. One background factor for this is that the current notification procedure does not function and thus smaller blasting sites are actually not monitored at all, nor are they even subject to a threat of monitoring. In addition, regulations regarding blasting work have been scattered amongst various administrative sectors’ provisions and instructions, which have been complemented over the decades. As a result, regulations can be obscure and even give rise to different interpretations.

The Investigation Commission recommends improving the prerequisites of blasting site monitoring and implementing this monitoring via annual checks, for instance. To clarify blasting regulations, the commission recommends that different ministries renew, update, and align the legislation related to explosives with an aim to removing details and moving toward independent risk management in the industry. However, renewals must cater for the needs of the industry’s broad small-enterprise field. In addition, the Investigation Commission recommends that operators in the quarry industry be mandated to take out sufficient liability insurance to ensure compensation for external sufferers of damage. To develop rescue services, the commission recommends that the Ministry of the Interior, in cooperation with the Association of Finnish Local and Regional Authorities, would find out how the address system and its updating is functioning and if it is needed to give more detailed regulations in addition to the existing guidelines.

B3/2006Y Report (pdf, 2.77 Mt)

Published 24.4.2006