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APPENDIX 3 — TAILINGS EMBANKMENT WELL TESTS <br />Ouray Silver Mines installed groundwater monitoring wells at the toe of the designated tailings <br />embankments along Sneffels Creek as part of the approved DRMS permit. These wells have <br />been tested at least quarterly since their installation. The groundwater that passes through the <br />Revenue and Atlas waste pile areas is properly intercepted by the wells GW -1, GW -2, and GW - <br />3. Each well location represents a pair of wells that are used to compare the water that might pass <br />through any tailings with the water that is present in the porous rock below the original topsoil <br />level. The (A) well in each location represents the background water, while the (B) well <br />represents water that may have passed through the tailings. Map G-14 of the approved <br />reclamation permit shows the locations of these wells. <br />The water in the wells briefly exceeded the limits imposed by DRMS in late 2014 and early <br />2015. However, values in the wells returned to below the limits, and it was determined that the <br />source of the metals of concern was old equipment and material buried within the old Revenue <br />waste pile. The pH of the groundwater in wells 2B and 3B, which is water that has passed <br />through the old Revenue waste, is consistently between 6 and 9. Given that the oxidization of <br />sulfide minerals such as galena and sphalerite are what typically produces dissolved metals in a <br />mine of this type, it would be expected that elevated levels of dissolved metals would be <br />accompanied by low pH. The roughly neutral pH, combined with the decline in dissolved metals <br />of concern later in the year leads GLA and Ouray Silver Mines staff to believe that it is a <br />washing out of old waste disturbed during the construction of the wells and the mine water pond <br />that generated the short term spike in dissolved metals. Construction like that has occurred <br />allowed fresh oxygen to interact with some of this old waste, thus causing a flushing of metals. <br />As can be seen in Table 1, the dissolved metal values are below the limits in the DRMS permit as <br />of June 2015, and quarterly sample results will continue to be reported to DRMS throughout the <br />life of the permit. <br />The wells are purged and sampled at least quarterly, with additional samples being taken as <br />desired. Wells GW -1A and B have had sampling discontinued, as no activity has taken place at <br />the Atlas area. <br />