2010-05-12_PERMIT FILE - C1981010

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 5/12/2010
• Doc Name: Revised K-Pit Butttress Fill Stability Analysis, Feb 2010
• Section_Exhibit Name: Appendix T
• Media Type: D
• Archive: No

February 1, 2010
Page 4
properties are presented in Table 1. The Mohr - Coul.omb constitutive model was assigned to all
layers.
Table 1. Geotechnical Properties of Materials in K -Pit and Toe
Buttress FLAC /Slope and SLOPE /W Models
The material properties for the spoils are based on previously- established empirical
relationships for similar spoils (Douglass and Bailey 1983) . and in -situ moisture - density test
results (Capstone 2008). The material. properties for the spoils within the reclaimed G- Strike -Pit
were assigned weaker strength parameters, as they have been disturbed by their collision with the
slide block.
The basis of design is summarized below:
• The calibrated rock -mass properties from the G -Pit landslide FLAC31) model were used
and an elasto- plastic Mohr - Coulomb material behavior was assumed.
• In -situ stresses increased with depth, assuming the gravitational weight of each l.ithologic
layer.
• Groundwater seepage was not directly simulated; rather, an effective stress analysis was
performed with pore pressure based on the depth below an assumed water table. The
phreatic surface was computed from straight lines between specified groundwater
elevation points. The rock -mass density was assumed to be saturated below the phreatic
surface.
• The volume of K -Pit buttress fill is 1.0 million cubic yards.
• The anticipated make -up of the fill is 70% sandstone and 30% shale.
• The maximum slope of fill is 3H:1V.
• The placement method will be 100% truck.
Agapito Associates, Inc.
Rock Mechanics Properties
Layer
Stratum
Dry Density
Cohesion
Friction Angle
No
(pc')
(ksf)
(degrees)
I
Overburden
145.9
0.7
11.0
2
[ -Seam materials
126.3
0.5
3.8
3
K -Seam materials
137.3
0.5
15.2
4
L -Seam materials
137.3
0.5
15.2
5
M -Seam materials
126.5
1.4
10.3
6
Q -Seam materials
110.0
0.1
20.8
7
R -Seam materials
139.5
35.1
24.1
8
Spoils
120.0
1.3
20.0
9
Disturbed spoils
115.0
0.1
9.0
The material properties for the spoils are based on previously- established empirical
relationships for similar spoils (Douglass and Bailey 1983) . and in -situ moisture - density test
results (Capstone 2008). The material. properties for the spoils within the reclaimed G- Strike -Pit
were assigned weaker strength parameters, as they have been disturbed by their collision with the
slide block.
The basis of design is summarized below:
• The calibrated rock -mass properties from the G -Pit landslide FLAC31) model were used
and an elasto- plastic Mohr - Coulomb material behavior was assumed.
• In -situ stresses increased with depth, assuming the gravitational weight of each l.ithologic
layer.
• Groundwater seepage was not directly simulated; rather, an effective stress analysis was
performed with pore pressure based on the depth below an assumed water table. The
phreatic surface was computed from straight lines between specified groundwater
elevation points. The rock -mass density was assumed to be saturated below the phreatic
surface.
• The volume of K -Pit buttress fill is 1.0 million cubic yards.
• The anticipated make -up of the fill is 70% sandstone and 30% shale.
• The maximum slope of fill is 3H:1V.
• The placement method will be 100% truck.
Agapito Associates, Inc.