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<br />1.0 INTRODUCTION <br />It is proposed to perform column leach test using the recently <br />produced tailings product from the Saa Luis Project. I~ is our <br />understanding that these columns are to model immediate post reclamation <br />conditions. Therefore these columns will model the potential leachate <br />quality, xhich could be produced from the underdrains. Several parameters <br />would influence the quality of this leachate and could be categorized into <br />two groups, physical and geochemical. <br />This discussion serves to outline the anticipated tailings condition <br />at the site and at the same time suggest xhat are the co tributinq <br />parameters, xithin each of the groups (physical and geochem cal), to <br />leachate production. Of these parameters, we need to determine ~hich ones <br />xould have a dramatic impact on the quality of the potential le chate. It <br />should be reminded that this is potential leachate, which could be <br />discharging from the underdrains and not xhat would be imps ling the <br />groundxater system of the region. <br />The leachate quantity xould be in direct correlation to ~ngth and <br />duration of xettinq events that the tailing mass could experi nce. Some <br />of the physical parameters, such as permeability of the taili qs mass, <br />evaporation rates of the site, would also affect the quantity of~leachate. <br />The column tests are not intended to determine the quantity of leachate <br />produced during any given time span. <br />2.0 CSNBRAL 11N1'ICIPIITSD SITB CONDITIONS <br />The tailings as deposited into the impoundment xould l~e doubly <br />drained (top and bottom), during the operating life of the mine. Such a <br />condition will probably produce tailings, which rill be both sat rated and <br />unsaturated. Ultimately, all the tailings rill be unsatur red with <br />occasional seasonal xettinq fronts migrating doxnxard through th~ tailings <br />to the underdrains. <br />The saturated conditions xould exist is a plume directly beneath the <br />operating pool of rater, to be maintained during mine operation. olloxinq <br />reclamation both the top and bottom portion of these areas xou d become <br />unsaturated. The middle section of this mass though, could stil be in a <br />saturated state for some time. Tailings located in the beach are s as well <br />as against the embantment xould probably be unsaturated. If the tailings <br />products rhea exposed to alternating cycles of air and water tend to <br />oxidize, then the saturated tailings xould probably not oxidi a during <br />the life of the project. These tailings xould probably start t oxidize <br />at some point after reclamation. <br />Based on the design of the tailings underdrain system, fir xould <br />be alloxed to enter the tailings mass at the bottom of the depos~t. If as <br />previously stated, the tailings tend to oxidize then the un aturated <br />tailings could start to oxidize during the operating life of the~mine an8 <br />therefore any leachate produced immediately after reclamation coul contain <br />the products of oxidization. <br />