2017-03-29_REPORT - C1982056

• Permit No: C1982056
• IBM Index Class Name: Report
• Doc Date: 3/29/2017
• Doc Name: Quarterly Subsidence Monitoring Report
• From: Twentymile Coal, LLC
• To: DRMS
• Permit Index Doc Type: Subsidence Report
• Email Name: TNL
• Email Name: DIH
• Media Type: D
• Archive: No

• Maximum compression zone located
within a
3.2 Predicting Subsidence
zone approximately 200 to
400 -ft from the start
Figure 5 was derived from numerous subsidence
room.
monitoring networks and represents the relationship
between the width/depth ratio and maximum
subsidence for the project site. These data are stored
Table 2.
Start subsidence
profile for panel
no. 1.
in a look -up table in the computerized, empirical
Distance
Distance
Subsidence
Subsidence
Subsidence
tool and are used in conjunction with the
from
from Start
after
after
after
prediction
Stable
Room
Panel 1
Panel 2
Panel 3
accumulated profile data to create three dimensional,
Point (ft)
(ft)
(in)
(in)
(in)
time phased subsidence predictions for future
0
-1200
0.00
0.00
0.00
planned layouts. Close agreement has been realized
200
-1000
0.77
0.04
0.85
between predicted and actual subsidence magnitudes
400
-800
1.35
-0.02
1.18
and limits as illustrated in the example presented in
600
-600
0.16
-0.19
-0.25
the following section.
800
-400
0.26
-1.70
-0.53
1000
-200
-0.11
-2.32
-2.35
1200
0
-7.39
-11.71
-13.21
1400
200
-33.74
-42.13
-43.51
1600
400
-44.62
-56.14
-57.43
1800
600
-43.52
-56.00
-57.74
2000
800
-43.35
-53.93
-57.07
100%
90%
r 80%
2
x
E 70%
W
0 60%
a)
as
v 50%
as
IL
40%
d
W 30%
;a
in 20%
10%
0%
0 0.2 0.4 0.6 0.8 1 1.2
Panel Width/Depth
Fi,,ure 5
Maximum Subsidence vs Width/Depth Ratio
I
I
i
■
0 0.2 0.4 0.6 0.8 1 1.2
Panel Width/Depth
Fi,,ure 5
Maximum Subsidence vs Width/Depth Ratio