During its December 2003 comprehensive performance test (required by the hazardous waste combustor MACT), Von Roll established 0.82 pound per hour (lb/hr) as its 12-hour rolling average mercury feed rate operating parameter limit. On August 25, 2005 at approximately 15:50 hrs, Von Roll incinerated a 5-gallon lab pack that contained as much as 18.1 pounds of mercury. Von Roll discovered the violation through an audit of the incineration of lab packs. On August 31, 2005, Von Roll reported the maximum 12-hour rolling average mercury feed rate during the first 12 hours after the bucket was incinerated to be 1.61 lbs/hr. In order to prevent reoccurrences of this type of violation, Von Roll is rotating chemists (who better understand the analyses of incoming waste streams) between the lab and the waste receiving area.