Geology Reference
In-Depth Information
16.2. Fire-Control
Projects in
Abandoned Mines
and Waste Banks
Fire in abandoned mine in
Large, Pennsylvania, 1976,
prior to installation of an
outcrop seal. Opening is
approximately 0.6 m by
0.1 m (2 ft by 1 ft).
Photo Courtesy of Dominion Resources.
Introduction
P rior to 1949 in the United States, no Federal or State agency collected information on the prevalence of fires in
inactive or abandoned mines and waste banks. After 1949, in conjunction with its work on the control of fires in
abandoned underground mines and in outcrops, the Bureau of Mines published reports listing fire-control projects,
extinguishment methods and costs. For the work done by the Bureau of Mines, the country was divided into three
regions: the Eastern bituminous region, the Anthracite region and the Western region including Alaska (Figure 16.2.1.).
Eastern Bituminous Region
B etween 1949 and 1960, there were 23 fire-control projects in the Eastern bituminous region (Griffith et al., 1960).
In the next 12 years, the Bureau participated in an additional 47 fire-control projects (Magnuson, 1974). Three of
these projects were located in West Virginia, one in Kentucky, one in Maryland and the remaining 65 were in
western Pennsylvania. In 1979, the Bureau listed 52 mine fires in the Eastern bituminous region (Johnson and
Miller, 1979). Surface sealing, alone or in combination with other methods was used on 45% of the fire-control
projects. Ten percent of the fires were excavated, and fire barriers were used at 27. At 15% of the fire-control
projects, either dry fly ash or fly ash slurry was injected to control the fire.
Surface sealing was popular because it was considered the only economically feasible method for attacking an
established fire under deep cover. The purpose of the seal was to limit ventilation of the fire zone and smother the
fire with accumulated CO 2 generated by the fire. Surface seals, if well maintained while the fire area cooled, were
considered a successful fire-control method. Excavation (or loading out) involved removal and cooling of all
burning material before the area was backfilled with incombustible material. It was considered appropriate for
recent fires under shallow cover. Economics and equipment limited its use in deep, widespread fires. A fire barrier
was an incombustible dam placed between the fire zone and adjacent coal. Its purpose was to limit the fire by
breaking the continuity of the coal and overlying carbonaceous shale. It had to be wide enough to prevent heat
transfer across the barrier. It was assumed that the fire would be extinguished when all the coal on the hot side was
consumed. The installation of a flushed barrier was intended to fill voids in a fire zone with incombustible
material in order to decrease the flow of air. It was considered effective for small fires in flat coal beds (Griffeth
et al., 1960; Magnuson, 1974). Overall, excavation was the most expensive control method, but it was also the most
effective. Surface seals were the least costly, but were only moderately effective (Table 16.2.1.).
Three experiments were conducted on water injection at an abandoned mine fire in the Pittsburgh coal bed to
develop more effective and efficient fire-control methods. In the first experiment, water was injected through uncased
boreholes into the hot area of the mine. Although the fire seemed to be extinguished in the central area of the fire
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