Pulacayo Project Feasibility Study - Apogee Silver

Pulacayo 1 000 t/d Phase I Feasibility Study - NI 43-101 Technical Report
090644-3-0000-20-IFI-100
Table 18.6: TSF Water Balance Results with 100-Year, 24 Hour Storm Event
Subdrain Monitoring Ports
Emergency Pond
Month
Flow
(m 3 /h)
Residence
Time
(h)
Flow
(m 3 /h)
Residence
Time
(h)
January 2.2 7 8.1 215
February 1.9 8 9.0 195
March 1.4 10 8.1 215
April 1.1 14 8.4 208
May 1 15 8.1 215
June 1.1 14 8.4 208
July 1 15 8.1 215
August 1 15 8.1 215
September 1.1 14 8.4 208
October 1 14 8.1 215
November 1.1 13 8.4 208
December 1.5 10 8.1 215
18.9.12 TSF Stability Evaluation
The dikes and tailings deposit were analyzed for slope stability under static (normal) and pseudostatic
(earthquake) conditions. Additionally, the earthquake-induced deformations were
estimated. A seismicity study was completed to determine the design peak ground acceleration
(PGA). Based on the available literature and other studies performed in the area, and based on a
return interval of 475 years, the design PGA is 0.2 g. This is the value that was used in the
deformation analysis. Based on standard convention and the guidelines published by the US
Army Corps of Engineers, for the purposes of the pseudo-static analysis only, the PGA was
reduced by 50% to 0.1 g. The geotechnical parameters used and the results of these analyses
are summarized in the following tables.
The yield acceleration, Ky, is the ground acceleration, which causes initial or incipient yield within
the considered mass. When the required acceleration to produce yield (Ky) is greater than the
design acceleration to be imparted to the TSF (PGA), the expected deformations are very small.
That is the case here, with predicted deformations of under 20 mm. For these types of facilities, it
is generally accepted that deformations of under 1.0 m will not seriously affect the performance of
the facility. Therefore, the predicted deformations should cause no damage or performance
problems within the TSF and will likely be hard even to detect
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