6
location. Measurements for the Uniontown horizon exhibit
a different pattern and are lower. The maximum permeabil-
ity at the Uniontown horizon is 245 mD. The minimum
measurement for the Uniontown is measured when the LW
panel is 152 m (500 ft) from the monitoring borehole
position.
Figure 8 displays the permeability measurements
before, during, and after the second LW panel mine-by. As
seen here, the permeability at the Sewickley horizon sig-
nificantly increases during the 2nd LW panel mine-by to
5,080 mD before decreasing after the mine-by. When the
LW panel is about 3,000 ft from the monitoring boreholes,
the permeability measurement was just above 1,000 mD.
The Uniontown horizon permeability measurements were
significantly lower with a maximum measurement of 386
mD. When the LW panel was 3,000 ft from the moni-
toring boreholes, the permeability measurement at the
Uniontown horizon was 161 mD.
A summary of the measurements is listed in Table 1.
At the Sewickley and Uniontown horizons, permeabilities
increase as the first longwall face approaches the measure-
ment site. After the mine-by, permeability in the Uniontown
horizon reduces to close to its pre-mining values but climbs
back to the maximum values. However, permeability val-
ues at the Sewickley keep climbing to 1,360 mD. Previous
NIOSH works [14] showed that permeability changes
are directly related to the proximity to the mining level
and inversely related to the depth of cover. The depth of
Figure 7. Permeability measurements at a shallow cover site during the first LW panel mine-by. Negative
distances are the LW panel approaching the monitoring boreholes
Figure 8, Permeability measurements at a shallow cover site during the second LW panel mine-by. Negative
distances are the LW panel approaching the monitoring boreholes
location. Measurements for the Uniontown horizon exhibit
a different pattern and are lower. The maximum permeabil-
ity at the Uniontown horizon is 245 mD. The minimum
measurement for the Uniontown is measured when the LW
panel is 152 m (500 ft) from the monitoring borehole
position.
Figure 8 displays the permeability measurements
before, during, and after the second LW panel mine-by. As
seen here, the permeability at the Sewickley horizon sig-
nificantly increases during the 2nd LW panel mine-by to
5,080 mD before decreasing after the mine-by. When the
LW panel is about 3,000 ft from the monitoring boreholes,
the permeability measurement was just above 1,000 mD.
The Uniontown horizon permeability measurements were
significantly lower with a maximum measurement of 386
mD. When the LW panel was 3,000 ft from the moni-
toring boreholes, the permeability measurement at the
Uniontown horizon was 161 mD.
A summary of the measurements is listed in Table 1.
At the Sewickley and Uniontown horizons, permeabilities
increase as the first longwall face approaches the measure-
ment site. After the mine-by, permeability in the Uniontown
horizon reduces to close to its pre-mining values but climbs
back to the maximum values. However, permeability val-
ues at the Sewickley keep climbing to 1,360 mD. Previous
NIOSH works [14] showed that permeability changes
are directly related to the proximity to the mining level
and inversely related to the depth of cover. The depth of
Figure 7. Permeability measurements at a shallow cover site during the first LW panel mine-by. Negative
distances are the LW panel approaching the monitoring boreholes
Figure 8, Permeability measurements at a shallow cover site during the second LW panel mine-by. Negative
distances are the LW panel approaching the monitoring boreholes