"Legally required water systems at Massey Energy's Upper Big Branch coal mine in West Virginia were not functioning properly before the April 5 explosion that killed 29 mineworkers, according to multiple sources familiar with the disaster investigation.

Some mine safety experts believe that these safety systems might have helped prevent the explosion if they had been working as designed."

Howard Berkes reports for NPR's All Things Considered January 14, 2011. [2]