Park dispatch received a smoke alarm activation signal from the Wawona Hotel Annex late on the morning of May 26th. Engine 2 from Wawona was paged and arrived on scene shortly thereafter. Upon arrival, the incident commander found that the fire alarm was sounding with no smoke showing. The IC was approached by hotel concession staff, who informed him that there had been an explosion in the Annex boiler room and that the guest rooms had not been completely evacuated at that time. An initial size-up investigation confirmed smoke present in the basement and damage to the boiler and chimney, but that no flame was visible. The IC requested additional resources for possible fire extension while the engine company began a building search to confirm complete evacuation, advanced hose lines and began a search for fire extension. An additional page was made for NPS resources, including Valley Engine 3, El Portal Engine 1, the chief fire officer, the fire marshal, and Ambulance 4 from Wawona. Mutual aid response was initiated with Mariposa County Engine 33 from the neighboring community of Fish Camp and Sierra Paramedic 12 Ambulance was dispatched from Bass Lake. After completing a thorough search of the building, the IC cancelled responding fire and EMS resources, remaining on scene for fire watch. Investigation by the chief officer and fire marshal confirmed that an explosion had occurred. The explosion in the fuel-oil-fired boiler occurred after a burner flameout. Fuel oil vapor had built up in the combustion chamber and when exposed to a hot surface rapidly vaporized and ignited. The force of the firebox explosion had broken three bolts off the boiler door, causing the 100+ pound door to completely separate from the furnace and land several feet away – where a hotel employee had walked just seconds before. The force of the explosion also lifted the approximately 40 pound chimney cap over 50 feet into the air, landing on a pedestrian walkway. No injuries were reported. The loss of the boiler has impacted the operation of the Wawona Hotel and consequently the visitor experience.
