9
equivalent mine volumetric flowrate and methane percent-
age by using the geometrical and aerodynamic scaling fac-
tors given by Gangrade et al. [9]. Volumetric flowrates were
not able to be defined in certain areas of the model, such
as the GOB and GOB MID, due to the unconfined nature
of the sample location. However, Table 8 lists the average
volumetric flowrates for the TG#3, TG BLD, TG BLD
BEP, and FACE locations. The higher standard deviations
for Test Series D compared to the other test series may be
due to the miner position change from Shield 115, close to
the tailgate entry, for the first test to Shield 35 nearer to the
headgate entry for the second test. All other test series had
the miner located at the miner located at Shield 35 nearer
to the headgate entry.
After geometrical and aerodynamic scaling factors
were applied to the individual test results [9], the sample
locations having more than trace amounts of equivalent
methane were determined to be at the tailgate bleeder (TG
BLD) and the tailgate bleeder BEP (TG BLD BEP). The
average equivalent methane percentages are listed for these
sample locations in Table 9. On average, the tailgate bleeder
showed less than 0.4% equivalent methane. The tailgate
bleeder BEP showed less than 1.5% equivalent methane.
Given this information, the tailgate bleeder entry and the
tailgate bleeder BEP are locations where a mine may want
to focus monitoring efforts. These results also confirm
the mine ventilation system’s ability to comply with the
requirements of 30 CFR Part 75 of the Mandatory Safety
Standards for Underground Mines. Given that all the other
sample locations had indicated little to no equivalent meth-
ane present, this indicates that the likely methane inflow
migration paths would not impact workers on the face,
energized power sources, or gob areas.
CONCLUSION
The LIAM has been configured with airflow quantities and
ventilation controls from cooperating mines to design spe-
cific test scenarios. The ventilation controls, airflow coursed
pathways, and examination locations are commonly
approved by MSHA for operating mines in the Pittsburgh
Coal Seam. Each sample location tested during the four-
test series was selected based upon critical locations to the
mine ventilation system and the possible impact to miners’
safety and production. Variations to the intake air quantities
coursed from the headgate entries onto the longwall face,
and intake air into the mine bleeder system and tailgate
entry were utilized during series testing. Gas inflow from a
hypothetical gas well breach at 340 cfm, 400, cfm, and 500
cfm air flow quantities were inserted at 30 locations in the
tailgate corner gob and tailgate pillar (in the gob).
The gas was introduced to simulate the movement of
a breach gas through the mine roof fractures into the mine
ventilation system. Migration characteristics in the mine
ventilation system and gas concentrations at critical loca-
tions were sampled and analyzed. Inflow values and gas
insertion locations were provided by NIOSH researchers
using DFN, 3DEC software, and Network modelers. At
no time was gas detected on the longwall face or tailgate
drive area.
The results confirm the mine ventilation systems’
ability to successfully course, dilute, and render harmless
inserted gas where power would be energized, and miners
could be working at locations in the underground mine.
Minimal amounts of gas were detected in the mined gob
areas with no accumulations detected at sample locations
in the gob. Results confirm the mine’s ability to comply
with the requirements of 30 CFR Part 75 of the Mandatory
Safety Standards for Underground Mines [14] and sug-
gest the monitoring of the tailgate bleeder and the tailgate
bleeder BEP. The different ventilation system designs did
not modify the overall trends in the distribution of gas from
the hypothetical breach. The LIAM tracer gas data offers
Table 8. Average volumetric flowrates for the TG#3, TG BLD, TG BLD BEP, and the FACE sample locations
Test Series
A 3 12568 ± 92 20222 ± 109 23480 ± 434 55085 ± 280
B 3 7405 ± 89 19250 ± 163 25231 ± 248 52538 ± 294
C 3 7363 ± 29 19104 ± 77 25149 ± 68 52198 ± 423
D 2 7107 ± 249 21736 ± 4509 20023 ± 446 52042 ± 952
No. of
tests in TG BLD BEP TG BLD TG#3 FACE
Sample Location Average Volumetric Velocities (cfm) ± standard deviation
Table 9. Average methane equivalent percentage is given
at TG BLD and TG BLD BEP sample locations for all test
series
Test Series TG BLD TG BLD BEP
A 340 0.13 1.09
B 400 0.31 1.33
C 400 0.14 1.00
D 500 0.33 1.42
Inflow
Rate (cfm)
Methane Equivalent (%)
equivalent mine volumetric flowrate and methane percent-
age by using the geometrical and aerodynamic scaling fac-
tors given by Gangrade et al. [9]. Volumetric flowrates were
not able to be defined in certain areas of the model, such
as the GOB and GOB MID, due to the unconfined nature
of the sample location. However, Table 8 lists the average
volumetric flowrates for the TG#3, TG BLD, TG BLD
BEP, and FACE locations. The higher standard deviations
for Test Series D compared to the other test series may be
due to the miner position change from Shield 115, close to
the tailgate entry, for the first test to Shield 35 nearer to the
headgate entry for the second test. All other test series had
the miner located at the miner located at Shield 35 nearer
to the headgate entry.
After geometrical and aerodynamic scaling factors
were applied to the individual test results [9], the sample
locations having more than trace amounts of equivalent
methane were determined to be at the tailgate bleeder (TG
BLD) and the tailgate bleeder BEP (TG BLD BEP). The
average equivalent methane percentages are listed for these
sample locations in Table 9. On average, the tailgate bleeder
showed less than 0.4% equivalent methane. The tailgate
bleeder BEP showed less than 1.5% equivalent methane.
Given this information, the tailgate bleeder entry and the
tailgate bleeder BEP are locations where a mine may want
to focus monitoring efforts. These results also confirm
the mine ventilation system’s ability to comply with the
requirements of 30 CFR Part 75 of the Mandatory Safety
Standards for Underground Mines. Given that all the other
sample locations had indicated little to no equivalent meth-
ane present, this indicates that the likely methane inflow
migration paths would not impact workers on the face,
energized power sources, or gob areas.
CONCLUSION
The LIAM has been configured with airflow quantities and
ventilation controls from cooperating mines to design spe-
cific test scenarios. The ventilation controls, airflow coursed
pathways, and examination locations are commonly
approved by MSHA for operating mines in the Pittsburgh
Coal Seam. Each sample location tested during the four-
test series was selected based upon critical locations to the
mine ventilation system and the possible impact to miners’
safety and production. Variations to the intake air quantities
coursed from the headgate entries onto the longwall face,
and intake air into the mine bleeder system and tailgate
entry were utilized during series testing. Gas inflow from a
hypothetical gas well breach at 340 cfm, 400, cfm, and 500
cfm air flow quantities were inserted at 30 locations in the
tailgate corner gob and tailgate pillar (in the gob).
The gas was introduced to simulate the movement of
a breach gas through the mine roof fractures into the mine
ventilation system. Migration characteristics in the mine
ventilation system and gas concentrations at critical loca-
tions were sampled and analyzed. Inflow values and gas
insertion locations were provided by NIOSH researchers
using DFN, 3DEC software, and Network modelers. At
no time was gas detected on the longwall face or tailgate
drive area.
The results confirm the mine ventilation systems’
ability to successfully course, dilute, and render harmless
inserted gas where power would be energized, and miners
could be working at locations in the underground mine.
Minimal amounts of gas were detected in the mined gob
areas with no accumulations detected at sample locations
in the gob. Results confirm the mine’s ability to comply
with the requirements of 30 CFR Part 75 of the Mandatory
Safety Standards for Underground Mines [14] and sug-
gest the monitoring of the tailgate bleeder and the tailgate
bleeder BEP. The different ventilation system designs did
not modify the overall trends in the distribution of gas from
the hypothetical breach. The LIAM tracer gas data offers
Table 8. Average volumetric flowrates for the TG#3, TG BLD, TG BLD BEP, and the FACE sample locations
Test Series
A 3 12568 ± 92 20222 ± 109 23480 ± 434 55085 ± 280
B 3 7405 ± 89 19250 ± 163 25231 ± 248 52538 ± 294
C 3 7363 ± 29 19104 ± 77 25149 ± 68 52198 ± 423
D 2 7107 ± 249 21736 ± 4509 20023 ± 446 52042 ± 952
No. of
tests in TG BLD BEP TG BLD TG#3 FACE
Sample Location Average Volumetric Velocities (cfm) ± standard deviation
Table 9. Average methane equivalent percentage is given
at TG BLD and TG BLD BEP sample locations for all test
series
Test Series TG BLD TG BLD BEP
A 340 0.13 1.09
B 400 0.31 1.33
C 400 0.14 1.00
D 500 0.33 1.42
Inflow
Rate (cfm)
Methane Equivalent (%)