2020-10-22_PERMIT FILE - C1981012A ‎(4)‎

• Permit No: C1981012A
• IBM Index Class Name: Permit File
• Doc Date: 10/22/2020
• Section_Exhibit Name: Section 2.05 Operation and Reclamation Plan
• Media Type: D
• Archive: Yes

48
this, the water table was initially assumed to be no higher that the interface
between the pile and the foundation.
While it is unlikely that a high water table would form within the pile, the
stability of the embankment was also analyzed with a water surface placed within
the pile itself. The purpose of this was to estimate effects this high water table
might have on the stability and to evaluate the need, for any, for internal drainage.
The surface through the embankment was estimated by a procedure developed by
Casagrande (193 7) for flow through a homogeneous dam on an impervious
foundation. In this analysis, it is assumed that the water existed at the top of the
pile and that it drained to the toe of the embankment similar to flow through a
water retention impoundment.
A summary of the stability analysis results are presented below, along with the
minimum safety factors required by CMLRD regulations. The "foundation"
water condition relates to a ground water table existing at the interface between
the pile and the foundation strata while the "pile" condition refers to the water
level. As may be seen, the stability of the embankment was found to have an
acceptable factor of safety for all loading conditions as established by CMLRD.
Failure Surface
Req.
# 1 Foundation
Stability Results
Water condition
1.1 foundation
Interface 1.2 Pile
#2 Random Circle 2.1 foundation
Circle 2.2 Pile
Safety Factor Calc. Min
2.7
1.5
1.6
1.5
2.7
1.5
1.6
1.5
As presented above, the stability of the waste pile was found to have an
acceptable factor of safety based on the selected strength parameters for the waste
material. Parameters are presented in Exhibit 30. The actual strength of the static
and pseudo static safety factors for the low phreatic surface was 1.87 and 1.59,
respectively. The static and pseudostatic high phreatic surface were 1.61 and
1.44, respectively.
As discussed, it is assumed that the foundation material will be significantly
stronger that the pile itself. The critical failure areas would therefore occur within
the spoil pile and would not pass through the consolidated foundation strata. To
assure this, the pile was not placed on the terrace fan or the undifferentiated
surfcial material. In addition, all topsoil and shallow colluviums and soil cover
was removed from beneath the waste area, and the surface proof -rolled, prior to
placement of the pile. If the depths of the colluviums become excessive, then
additional studies should be conducted to estimate its behavior and determine
what effects, if any, this layer would have on the overall stability of the pile.
Section 2.05 RN -6 10/17/2016