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It is estimated that this permeable waste rock will constitute the bottom 20-30 feet of the Revenue TSF. <br /> Only the upper portion,as shown on Cross Section A-A' will be comprised of the combined tailings and <br /> waste rock that will be produced from the mining and milling operations. This upper portion(an <br /> additional 30-40 feet)will be compacted, and the lower portion (existing waste rock)will not since it is <br /> important to maintain permeability of this material. The slope stability of this "double layer"in the pile is <br /> addressed in one of the scenarios analyzed in Exhibit T(currently in the Geotechnical Exhibit),which <br /> was submitted in Amendment 1 and again as part of TR-15. As an additional level of protection,the <br /> southeast end of the Revenue TSF was built and graded at a vertical position above the rest of the pile,to <br /> create a protection berm against avalanche. <br /> 5.2.2 Atlas TSF <br /> The Atlas TSF has a total design capacity of roughly 300,000 tons. There are jurisdictional wetlands in <br /> this area which have been confirmed. These wetlands will be avoided during construction and during <br /> placement of waste materials. It is understood that Ouray Silver Mines will not be allowed to disturb the <br /> wetlands and if any wetlands are to be disturbed, an approved nationwide or individual permit must be <br /> supplied to the DRMS. The Atlas TSF is currently being constructed on the moderately flat area west of <br /> the main Revenue portal area and has been regraded to provide a flat area for the pile and related <br /> sediment pond. The maximum height of the Atlas TSF will be 90 feet, and therefore a 10-foot-wide bench <br /> will be placed approximately 50 feet from the toe of the pile. <br /> 5.3 Waste Rock Storage <br /> Waste rock brought to the surface to be used for embankment, TSF construction or to be crushed as road <br /> base will be managed using the following best management practices(BMPs). <br /> 1) As required by TR-09,waste rock crushed for use off-site must be tested using the Synthetic <br /> Precipitation Leachate Procedure (SPLP)to ensure the material is suitable for use as a road base <br /> and will not cause environmental impacts. In the SPLP test,the waste rock is ground to a minute <br /> size (i.e., smaller than 9.5 millimeters)prior to leaching with a pH 5 solution,while the actual <br /> waste rock embankment site will have larger sized rocks up to 1.5 inches in diameter,that will <br /> not leach as readily. <br /> 2) Undisturbed runoff from the south hillside is diverted away from the waste rock embankment, <br /> using a diversion ditch designed for the 10-year,24-hour storm event. <br /> 3) The waste rock embankment will be covered with a minimum of six inches of topsoil and planted <br /> with a stable mix of vegetation well suited to this location and approved by DRMS. The <br /> vegetation will use most of the direct precipitation and surface water runoff that occurs on the <br /> reclaimed embankment. This will minimize the amount of water that can percolate into the <br /> reclaimed waste material. Details of this plan are shown in Exhibit E. <br /> 4) The gradual slopes and revegetated surface of the waste rock embankment will minimize erosion <br /> of topsoil and prevent exposure of the underlying waste rock. <br /> 5) Waste rock cannot make up more than 15%of the new material to be placed in the permanent <br /> TSFs,to prevent void spaces which may reduce compaction and provide conduits for water flow. <br /> 5.4 Soil Excavation and Stockpile Areas <br /> A majority of the Revenue Mine surface facility is located on existing disturbance from the historical <br /> mining activities.Historically,topsoil was not salvaged. For current excavation and earth moving <br /> activities,topsoil will be stripped from areas where it is identified prior to disturbance. Details of the <br /> existing site soils are presented in Exhibit I. <br /> Revenue Mine <br /> Amendment 02 D-16 <br /> December 2021 <br />