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3.0 STRUCTURAL STABILITY <br />3.1 SUMMARY OF EXISTING DATA AND ANALYSIS <br />3.1.1 Embankment Design <br />As discussed earlier, the tailing facility was built in two phases, with the Phase II having a <br />Raise 1 and Raise 2. A typical section of the dam at final buildout is depicted in Figure 3 below, <br />as reproduced from the Phase II, Raise 2 Design Report (SRK, 1995). The embankment has an <br />overall downstream slope flatter than 311:1 V with two 15 -foot wide benches associated with the <br />upstream raises that are built partially on tailing. <br />E PHASE II RAISE 2 <br />nn <br />PHASE I....._. "'.... ..... .. _�•• ,, .. _. CI PHASE d RAISE 1 <br />�M V o• ,. MATERIAL <br />S TYPE + <br />17 �/ aA15E x EL 8620' <br />RASSE + Et. 8805• .1% SLOPE <br />17-2- -- .. {._ _ __P _.__ Ef:'sTMG TAIL WGS El. 8600• <br />PHASE 1 EL. 8890' 1 EXISTWC` -3� MATE IA <br />TYPE 1 <br />I I 1, •• I �� t 5v -�1 <br />EIO.TING GRANULAR <br />EMBANKMENT "LL " —� EXISTING <br />(MATERIAL TYPE 81 �- MATERIAL TYPE 1 <br />2' PROTECTIVE COVER <br />(MATERIAL TYPE 21 <br />EXISTING FOU ATION LINER SYSTEM <br />__.... " " "_.. .. ....._ ..... ..........._._.............__.. <br />Ip ?TAIL 11 <br />'SEE DETAIL <br />OTEXTILE <br />FABRIC <br />MATERIAL <br />TYPE 3 <br />EXISTING <br />DRAINAGE BLANKET A LINER SYSTEM <br />8ECTION CS`,_'LSSAEQTION -A-&' <br />GENERALIZED <br />IDETAIL 21 <br />(Reproduced from SRK, 1995) <br />Figure 3 San Luis Tailing Dam Typical Cross Section <br />E BLANKET 8 LINER <br />IDETAIL 31 <br />The Phase II, Raise 2 Design Report represents the final existing structural stability analysis of <br />the facility and examined the following cases: <br />• Static loading conditions, where the stability of the embankment is examined under <br />normal operating conditions. Presumably this was done with more water in the facility <br />than is present now, but as described below, this cannot be verified. <br />• Liquefaction triggering of the tailing whereby weakening or liquefaction of the tailing <br />could occur during an earthquake design event. <br />• Pseudo static stability analyses, which are an older method of examining stability under <br />earthquake loading. <br />• Deformation and post- liquefaction settlement analyses associated with an earthquake <br />event, whereby the embankment could undergo some deformation. <br />San Luis Project Miller Geotechnical Consultants <br />Tailing Dam Data Report 7 February 2014 <br />