On November 6, 2007 at approximately 0800 hours, two (2) operations employees (Mathew
Indeglia, and Philip Robinson) and one maintenance employee (Mark Mansfield) were working
to tag out a pulverizer seal air fan under boiler #3. At 0846 hours, a series of division wall tubes
catastrophically failed within the east furnace lower slope dead air space. The steam boiler was
operating at 1900 PSI at the time of the failure. The furnace lower slope dead air space was
normally under a slight negative pressure. The failure of tubes within the furnace lower slope
dead air space caused that space to become rapidly pressurized resulting in a secondary
explosive rupture of the boiler casing around that space. It is believed that the tubes failed in a
pattern and manner as shown in this report as “apparent pattern of failure”. The failure caused
ash and steam/hot water, at a temperature of approximately 600°F, to be released toward the
immediate area where the three employees were standing. Based on witness accounts, the three
(3) employees were able to leave the area of the failure on their own, however, they all suffered