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TABLE 1.0 ANALYTICAL SUMMARY TABLE BIG FM DISCHARGE SAMPLES <br />Metals mwenirttioas eVressed in micrograms/Liter <br />Sampling Event As Cd CU Eg Mt Pb 7an <br />1995 Ph*" I RI 10 48 1710 NAF 19,700 91 9770 <br />1989 Pkase 11 RI LO 27 690 NAF 18,800 5 9100 <br />2001 CDPHE NAF 24 i500 NAF 32,200 NAF 9166 <br />2005 UOSO} 2 20 2%0 0.1 191500 16 7,610 <br />State Drinking Water MCL 10 3 - 2 <br />State Drinking Water MCLG <br />State Seoon MCL <br />1 - 1300 <br />100 - <br />- - <br />so 15 <br />500 <br />A antle Life NEClW P) 5 OA/3 grl 0.01 (4 1 1000/1493 4I2 47/200 11 <br />NAF a Not Analyzed For <br />MCL - Mazitnrm Contamiaant Level <br />MCLG - Maadnnm Co.taminamt Level Goal <br />NEC - No lRffeet Conc entradow are metal coneeatratlons at whick agratie We does not suffer any tosie effects <br />(1) UOS--START contractor for EPA's,Emergeucy Response Team <br />(2) WQCD - aquatic standards for Clear Creek Sepnem 2 <br />In the event there is infiltration into the groundwater table, the net quality could only significantly improve. <br />A current sampling of the Big 5 Tunnel discharge also follows in this Exhibit C. <br />This sampling was done over a period of time from 1985 - 2009. It becomes apparent that the reported metals <br />concentration varies widely. Rationale for this can be explained by variation in rainfall amounts preceding the <br />sampling and the concentration of that rainfall in different areas of differing mineralization. This wide variability <br />can not be attributed to active mining operations because we are not aware of any within this drainage area over this <br />period of time. <br />Tailings Impoundment Construction: <br />The impoundment and composite liner system is to be constructed on crystalline metamorphic and igneous rocks <br />with minimal hydraulic conductivity. A concrete barrier will be installed upon the up gradient face of the first earth- <br />fill terrace to minimize leachate through the structure (see Exhibit E). The natural slope, upon which the fill will <br />reside, is slightly less then 3h: Iv (± 18°). <br />Generally speaking, the Tailings Impoundment will be built up in a series of five benches utilizing an upstream <br />hydraulic placement and hydraulic classification method. A maximum of 40 square feet of new embankment face of <br />minimal height (10-12 ft. per year), built with the coarse fraction, will be formed daily giving more than adequate <br />time for consolidation and draining. A maximurn slope of 1.511 : Iv (} 33.7°) will be maintained at the embankment <br />free face. <br />Design guidance was taken in part utilizing Steven G. Vick's I'lanning, Design, and Analysis of Tailings Danis, <br />1990 and the US Army Corps of Engineers (USACE) Slope Stability, EM 1110-2-1902. These authoritative works <br />are cited in many EPA design and regulatory mandates. <br />Page 15 of 37