Fly ash grout snuffs stubborn coal refuse fire. [Ohio Edison power station]

A slurry made of fly ash and water can be used to extinguish a particularly difficult kind of fire--a burning pile of coal refuse. Not an uncommon problem in coal mining areas, such a fire had smoldered for several decades at a coal slag pile behind an Ohio Edison generating plant. The basic procedure involved driving pipes into and through the affected zones; placing a geothermal probe in the pipes to measure the underground temperature and delineate the extent of burning; injecting a fly ash/water slurry down the pipes into the burning zone to extinguish the burning and cool the hot material; and controlling the injection process and assuring completion of the job by a continuing program of temperature measurements.