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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 3H: IV with two 15 -foot wide benches associated with the <br />upstream raises that are built partially on tailing. <br />—I II <br />2' PROTECTIVE CCvER <br />T— 1MATERIAL TYPE 2) <br />' E %151 Mrs FDJNtA TION 1 <br />- - - - - - -� _11-1AIL Il <br />Y PIIAyL II RAI',[ 2 <br />4�YWtif +I� I 4 41 IL 11 RAISL 1 <br />MA1TRn- <br />I� I TrPE 1 <br />_ RAISE 2 EL A- <br />i - T - -- / L - -- <br />� PI_M1r,�Et P,SCT �t:f� <br />PHASE I ET 8,80' Ir E %IStING ___ <br />MATERI I <br />TYPE I -SEE DETAIL A <br />\, EXISTING GRANUI AR <br />EM8ANKMENT FIL. _\ <br />IMATERAL TYPE I <br />INES SYSTEM <br />r I� •GEOTE %TXE <br />FABP C <br />\ - MATERIAL <br />E %SSTING TYPE 2 <br />MATERIAL TYPE 1 __ <br />Ex STING <br />j' DRAINAGE 8L ANKET & LINER SYSTEM J <br />- IDE -AIL 21 <br />$ECTIONSC _OI <br />90EBA IM- EMBAYKYE 4T SAgQ$$- SECTi(!M g -e' <br />1•.50' <br />EXISTING DRAINAGE BLANKET & LINER SYSTEM <br />IDETAR GI <br />(Reproduced from SPX, 1995) <br />Figure 3 San Luis Tailing Dam Typical Cross Section <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 />