HYDRO29457

• Permit No: C1981022
• IBM Index Class Name: Hydrology
• Doc Date: 6/19/1985
• Doc Name: 4 DIP 6 EAST BOREHOLE ANALYSIS
• From: US STEEL MINING CO INC
• To: GLENN H SIDES
• Permit Index Doc Type: OTHER GROUND WATER
• Media Type: D
• Archive: No

..;
70: GLENN H. SIDES
General Manager
Western District
cc: V.R. WATTS
C. W. WINTERS
Sub)ect: 4-DIP/ 6-EAST BOREHOLE ANALYSIS
INTRODUCTION
u s U. S. Steel
III IIIIIIIIIIIIIIII
999
s Mining Co., Inc.
Interorganfzation Correspondence
Date: June 19, 1985
From: L. Badertscher ~
The Somerset Mine's 4-Dip panels have experienced high
methane liberations during retreat mining. Boreholes have been
drilled in the inby end of 4-East and 5-East panels to drain
the methane. These holes have been successful in reducing the
methane concentrations which the return airways have to handle.
PAST EXPERIENCE
In 4-East, after retreat mining had progressed 3 crosscuts
outby the borehole, benefits of the borehole became evident. With
the pump running, the flow was measured at 410cfm with 50%
methane, which is 205cfm of methane During mining in 4-East
with the pump idle or at present with the section sealed, the
system freeflows at 270cfm with 60% methane, which is about 160cfm
of methane. The total methane being liberated in both returns and
borehole during retreat mining in 4-East was between 500cfm and
600cfm. Since rooms were mined up the hill in 4-East, the top
return could not be designated a gob bleeder split. The borehole,
therefore, benefited 4-East ventilation by approximately 30,000
cfm, because methane concentrations had to be kept below 1%
at the cave line.
In 5-East, after retreat mining had progressed 4 crosscuts
outby the borehole, the borehole was freeflowing at 270cfm with
85% methane. The total methane liberated in both returns and bore-
hole at this time was approximately 700cfm. After retreat
mining had progressed 8 crosscuts outby the borehole, the bore-
hole was freeflowing 270cfm with 52% methane. The total methane
concentrations at the borehole can not be maintained high enough
to run the pump for any extended period of time. The present
air flows at the mouth of the section are 55,OOOcfm and 35,OOOcfm.
This borehole was originally reducing ventilation requirements by
over 20,OOOcfm in 5-East. Since this time the methane concen-
tration in the borehole has dropped, thereby reducing the bene-
fit from the borehole to 11,OOOcfm.
1