One of the guys I worked with, used to work there (10+ years ago). he was a "picker" (up to his neck in garbage). He had a boiler engineers licence and a crane licence. He told me the "blast door" would fly a quarter mile.
Started in the shredder ( possible propane tank but it could have been anything ) anti-stink vents sucked fire into the induced draft fan and things went down hill quickly from there. Looks like they will be off line for quite some time. Bright side...no one hurt! 2nd hand info.
Tom