Posted By Simon Wright
We are about to commence a relatively small construction project at the back of an established site in the tarmacadamed yard area. Soil investigations have defined it as an old landfill site and also that 'consistent levels of methane were being recorded above the lower explosive level (LEL) for methane of 5% volume gas'.

Does anyone have any suggestions or clarifications as to how dangerous this situation really is? What risk control measures do we need to put in place for the construction process (which will involve excavating for foundations) and also for the future use of this area? Do we need soil vents down into the landfill strata? Should we place restrictions on the use of the area i.e. no bonfires, naked flames around the vents or just in general? Just to complicate matters, the site is a fire service training centre and as you can expect naked flames are almost certain to be used at some time.

Does anyone have any pointers concerning the above or any anecdotes of methane gas emissions from soil causing explosions, etc? I would appreciate any links to established / accepted advice or information, or previous related discussion threads.

Many thanks for any comments provided.