2008-03-21_PERMIT FILE - C1980007A ‎(8)‎

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 3/21/2008
• Section_Exhibit Name: Exhibit 60E Subsidence Evaluation for the South of Divide & Dry Fork Mining Areas
• Media Type: D
• Archive: Yes

TABLE 3
MAXIMUM SUBSIDENCE PARAMETERS FOR
DRY FORK MINING AREA(1)
•
s
Parameter Panel E2 (t = 9 ft) Panels E3 - E6 (t = 10 ft)
W/d:(2) Max
Min E2: 1080 / 1000 = 1.08
1080 / 1000 = 0.9 E3: 1080 / 800 = 1.35
1080 / 1200 = 0.90
Max
Min E4: 1080 / 900 = 1.20
1080 / 1200 = 0.90
Max
Min E5: 1080 / 1000 = 1.08
1080 / 1200 = 0.90
Max
Min E6: 1080 /1200 = 6.90
1080 / 1400 = 0.77
t=9ft t=10ft
SAP = app * t (3)
acp=Scp/t 0.90 to 2.7 ft
(0.1 to 0.3) 1.0 to 3.0 ft
(0.1 to 0.3)
Sm= a. t(4)
a = Sm/t 5.9 to 6.1 ft
(0.6 to 0.8) 6.2 to 7.0
(0.62 to 0.70)
Sm/d (5) 0.0049 to 0.0061 0.0044 to 0.0088
Mm 2.2 to 2.3 Sm/d (6) 0.011 to 0.0140 0.010 to 0.019
Em (in terms of Sm/d) (7)
1.2 to 1.4 Sm/d 0.0059 to 0.0085 0.0062 to 0.010
-Em (in terms of Sm/d) (7)
-1.2 to -1.5 Sm/d -0.0059 to -0.0092 -0.0066 to -0.0106
1 5-10ft 5-10ft
Maximum Crack Depth( 8) 2 10 -20 ft 15 - 25 ft
Break Angle (9) 0-51 0 - 5°
Angle of Draw (9) 10 - 20° 10 - 20°
(1) Maximum tilt and strain parameters apply only to ground surfaces with slopes less that 30 percent; values
may be greater on slopes steeper than 30 percent.
(2) All panels are numbered according to planned panel identifications.
(3) Subsidence and subsidence factor above chain pillars.
(4) Subsidence (maximum vertical displacement) above longwall panel centers, based on planned coal extraction
thickness listed.
(5) Ratio of the range of maximum vertical displacement to overburden depth range for the nine planned longwall
panels.
(6) Maximum range of tilt in terms of Sm/d; values of 2.2 to 2.3 Sm/d are obtained from the graph in Figure 5.
(7) Maximum range of horizontal strain in terms of Sm/d; values for tensile (positive) strain of 1.2 to 1.4 Sm/d and
compressive (negative) strain of -1.2 to -1.5 Sm/d are obtained from the graph in Figure 5.
(8) Maximum crack depth (in feet) in bedrock predicted to locally occur on or near steep slopes and ledges in the
Minnesota Creek and Lick Creek drainage areas and above barrier pillars and rigid chain (gate road) pillars.
The first depth range (1) is for bedrock sloping less than, or equal to, 30 percent; the second depth range (2)
is for slopes more than 30 percent. Add 5 to 15 feet where thick, brittle sandstones occur in ridges and near
cliffs. No cracks are predicted to occur in alluvium. No cracks are predicted to occur at the surface of
colluvium thicker than about 10 feet.
(9) Angle measured from a vertical reference.
Tetra Tech - 090717/P 41