There was an explosion which injured two people in August 2009. A contractor had filled a pit with about 6m depth of foamed concrete. Whilst the concrete was setting, workers started removing steelwork using angle grinders. There was an explosion underneath the steel walkway on which two contractors were standing and which blew the steel plates and the workers up into the roof. Essentially hydrogen appears to have been generated by a reaction between aluminium in the Incinerator Bottom Ash and the cement/concrete. HSE have issued an interim position which includes guidance on the use of Foamed Concrete.

 Foamed-concrete-explosion-HSE-Interim-Position.pdf (14.95 KB)