Spontaneous combustion of shale spoils at a sanitary landfill

Shale deposits excavated from the Upper Cretaceous, Eagle Ford Formation for a sanitary landfill near Dallas, Texas spontaneously combusted. The shale is dark gray in color, with 3–4% fractional organic carbon, and no lignite seams. Gradual sifting and segregation of fine particles, having high surface area per unit volume, along with moisture trapped in the pile as it accumulated led to spontaneous combustion. Hot summer temperatures compounded the problem by heating the pile and preventing heat from efficiently venting to the atmosphere. Maximum temperatures exceeded 960 °F (516 °C) at several hot spots located approximately 4 m beneath the pile surface. The ongoing combustion problem, which has lasted for approximately 1 year, eventually will be extinguished by spreading the deposits in thin layers, and compacting them to reduce air circulation and segregation of fines.