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

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Point No. : MC-6
• Type : monitoring
Installed: 1981 Surveyed: 1982 , 83 , 7/84 , 9/84 , 8/85
Location (mine coordinate system) : 16550 . 98N, 4175 .36E
Original Elevation' (ft) : 10 ,448 .13
Total Movement Since Installation (ft) : -0 .48
Estimated Coal Removed Within Subsidence Zone (ft) : 8 .00
Subsidence Ratio: 0. 06
Location Relative to Mine Workings : over 3 North No. 3 mine;
890 ft NW of lw 205, No. 2 mine.
Discussion: this part. of 3 North apparently pillared early
19701s; probably in subsidence zone of more recent 2 North-
3 North pillaring, 1979-1980 . See Figure 11.
Point No. : MC-7
Type: monitoring
Installed: 1981 Surveyed: 1982 , 1983
Location (mine coordinate system) : 20252 . 64N, 2497 .51E
Original Elevation (ft) : 11 ,012 .54
Total Movement Since Installation (ft) : +0 . 01
Estimated Coal Removed Within Subsidence Zone (ft) : 10. 00
Subsidence ratio : less than 0. 01 (not surveyed after 1983)
Location Relative to Mine Workings : over 4 North No. 5 mine ,
250 ft SE of pillared area, 4-5 North.
Discussion: slight compression movement recorded 1982 , then
slight tension in 1983 . Both measurements within surveying
• margin of error (+/-0. 05 ft) . Adjacent pillar area worked
mid 82 ; additionalsubsidence probable since last survey.
See Figure 12 .
Point No. : MC-8
Type : monitoring
Installed: 1981 or 82 Surveyed: 1983 , 7/8.4 , 8/85
Location (mine coordinate system) : 16005 .24N, 802 . 10E
Original Elevation (ft) : 11 ,617 .69
Total Movement Since Installation (ft) : +0. 04
Estimated Coal Removed Within Subsidence Zone (ft) : none
Subsidence Ratio: --
Location Relative to Mine Workings : 790 ft SW of lw 301 No.
3 mine.
Discussion: assumed stable since installation; recorded move-
ments within surveying margin of error (+/-0 . 05 ft) . See
Figure 13.
Point No. : MC-9
Type: monitoring
Installed: 1981 or 82 Surveyed: 1983 , 8/85
Location (mine coordinate system) : 15475 .20N, 896 .68E
Original Elevation (ft) : 11 ,465.80
Total Movement Since Insatllation (ft) : +0 . 02
Estimated Coal Removed Within Subsidence Zone (ft) : none
• Subsidence Ratio: --
Location Relative to Mine Workings : 1 ,000 ft SW of lw 301