PRODUCTION OF A PHYSICAL MODEL OF THE CENTRALIA COAL FIRE

A physical model (at 1:1000 scale) of the Centralia coal fire was produced in an attempt to reproduce the heat pattern and distribution and types of gases produced by the combustion of anthracite coal. The stratigraphy of the Buck Mountain succession (Llewellyn Fm.- Pennsylvanian), the subsurface locations of breasts and pillars of coal, and the dip of the rock units associated with Fire Front 1 were replicated. A thin soil was placed over the model and grass was grown over the model. Charcoal was placed in a gangway and lit using fatwood and magnesuim coal starters. The fire was monitored using a FLIR p620 thermal infrared camera and a IBRIX M6 multigas meter; O2, CO2, CO, methane, and H2S were monitored in transects across the landscape along the strike and dip of the rock layers.

Though the anthracite coal never became hot enough to ignite, the heat from the charcoal provided realistic TIR patterns of how the heat is thought to circulate at Centralia. Heat flowed up the mined out breasts to the surface and was released at the coal-landscape intersection. Additionally, gases were highest in CO2 and depleted in O2 at this location, however when vents were drilled into the base of the model, both the heat and gases migrated away from the fire front, to more proximal locations above the vents. The drilling of vents was remnicent of boreholes drilled by the PA DEP. The vents caused a change in gas/heat movement and location, and they caused the fire to heat up more quickly. Eventually, the vents aided the fire in burning the model, which was extinguished.

Thi model may help us understand the influence of boreholes in monitoring coal fires. Though helpful in identying the location and depth of heat, gas composition andconcentrations, and potential movement of the fire, it's likely the boreholes caused the fire to speed up across the landscape and intensify with regard to heat.