1987-12-01_PERMIT FILE - C1981017 ‎(284)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Subsidence Study By Dr. Bruce Collins
• Section_Exhibit Name: Chapter IV Appendix IV-F-4
• Media Type: D
• Archive: No

13 -
• Point No. : MC-3
Type: monitoring
Installed: 1981 Surveyed: 1982 , 83 , 9/84 , 8/85
Location (mine coordinate system) : 10306 . 54N, 5365 .76E
Original Elevation (ft) : 11,127 .23
Total Movement Since Installation (ft) : -0 .90
Estimated Coal Removed Within Subsidence Zone (ft) : 8 . 00
Subsidence Ratio : 0.11
Location Relative to Mine Workings : over 7 North No. 1 mine,
over 4 North No. 2 mine.
Discussion: 7 North No. 1 mine worked mid-1973 . This point
probably stable before longwall 101 No. 1 mine began; area
mined early 1977 . Apparently in subsidence zone of long-
wall 101 and not yet stable . Over 4 North No. 2 mine devel-
opment only, no secondary mining close by. See Figure 8 .
Point No. : MC-4
Type : monitoring
Installed: 1981 Surveyed: 1982 , 83 , 7/84 , 9/84 , 8/85
Location (mine coordinate system) : 13681.20N, 4173 . 94E
Original Elevation (ft) : 11 ,431 .14
Total Movement Since Installation (ft) : -2 .10
Estimated Coal Removed Within Subsidence Zone (ft) : 16 .00
Subsidence Ratio : 0.13 (see discussion above and below)
Location Relative to Mine Workings: over 7 South No. 3 mine;
lower side of 4 North, below lw 203 , No. 2 mine. Will be
undermined by longwall 205 .
Discussion: probably over the greatest amount of coal removed
of any of the control or monitoring points, also has the
greatest amount of subsidence . 7 South No. 3 mine worked
late 1973 , essentially stable by 1981 , with most post-1983
movement due to longwall 203 , No. 2 mine (area mined early
to mid-1984) . If all post-1981 movement is ascribed to
longwall 203 , a subsidence ratio of 0 .26 results. Now
stable, no movement 1984-85. See Figure 9 .
Point No. : MC-5
Type: monitoring
Installed: 1981 Surveyed: 1982 , 83 , 7/84 , 9/84 , 8/85
Location (mine coordinate system) : 15557 .52N, 5832 .76E
Original Elevation (ft) : 11,010.41
Total Movement Since Installation (ft) : -1 .73
Estimated Coal Removed Within Subsidence Zone (ft) : 8 .00
Subsidence Ratio: 0.22
Location Relative to Mine Workings : over 1h North No. 3 mine;
west of bleeders between 1 and 2 North No. 2 mine.
Discussion: 1h North No. 3 mine apparently pillared in 1970
or 1971. In 2 North No. 3 mine subsidence zone; 2 North
and barrier between lZ and 2 North pillared late 1979 to
early 1980. Stable since 1983 survey. See Figure 10.