2022-07-12_PERMIT FILE - C1981019 ‎(14)‎

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 7/12/2022
• Doc Name: Geotechnical Report - Collom Out of Pit Dump and Final Reclaimed Surface
• Section_Exhibit Name: Volume 20 Exhibit 23 Item 3
• Media Type: D
• Archive: No

Mr. Lee Sampson
March 28, 2022
Page 7

Agapito Associates, Inc.

In terms of the out-of-pit dump, all assessed conditions for both Sections A and B achieve the
minimum stipulated factor of safety of 1.5 against static conditions and 1.3 for seismic conditions
and are therefore deemed adequate for temporary stability.

Under all the conditions assessed for the final reclaimed surface, the slopes assessed in both
Sections A and B achieve the minimum stipulated factor of safety of 1.5 against static conditions
and 1.3 for seismic conditions and are therefore deemed adequate for long-term stability.

If you have any questions, please feel free to contact me.

Sincerely,

Ry Stone, CPEng.
Senior Associate

RS/TVD:klg
Attachment: Stability Assessment Results
Transmitted in PDF format via email to [e-mail]

Table 2. Summary of SLOPE/W Results for Sections A and B of the Collom Out-of-Pit Dump
Section

Seismic Conditions

Water Level Relative
to Base of Spoil
(ft)
Factor of Safety
(Toe Failure)
Factor of
Safety
(Crest Failure)
Section A Static –15 3.0 2.1
Section A Static +40 2.4 1.6
Section A Pseudo-static +40 2.2 1.4
Section B Static –15 2.9 1.5
Section B Pseudo-static -15 2.4 1.4
Table 3. Summary of SLOPE/W Results for Sections A and B of the Final Reclaimed Surface
Section

Seismic Conditions

Water Level Relative
to Base of Spoil
(ft)
Factor of Safety
(Toe Failure)
Factor of
Safety
(Crest Failure)
Section A Static –15 3.9 3.0
Section A Static +40 2.8 2.0
Section A Pseudo-static +40 2.2 1.6
Section B Static –15 2.9 2.4
Section B Pseudo-static -15 2.2 2.1