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considerable water was flowing in the gravel below the surface. We know that the source of this <br />water, the Atlas portal higher on the mountain, flows all year. This water is the poorest of all <br />waters measured and has nothing to do with the Revenue Mine. It is by far the largest contributor to <br />zinc concentrations downstream. <br />The Atlas Drift and Revenue Tunnel inby the Atlas Drift were only sampled in Q1 2012, thus <br />making that set of data the most complete regarding ground water. When the mass flow balance <br />from Table T -1 for Q1 2012 is analyzed, it appears as if the dissolved zinc drops significantly from <br />the water flow in the Revenue Tunnel. The zinc mass flow at the Revenue Tunnel inby the Yellow <br />Rose Drift (0.49 g/hr) should be the same as the combined Revenue Tunnel inby the Atlas Drift and <br />Atlas Drift itself (0.03 +2.98 = 3.01 g/hr), but it is not. Similarly to the surface water, zinc is <br />dropping out of the water flows. The data also shows that the major contributor of zinc in the <br />Revenue Mine water is from the Atlas drift. Although the flow rate is relatively small, the quality is <br />poor. <br />Both the ground water and surface water regimes at Revenue have a contribution of zinc laden <br />water from the Atlas Mine followed by a slow decrease in the dissolved zinc content of the water as <br />it flows downstream. Based on the data available, it is evident that dissolved zinc is dropping out of <br />the mine water and Sneffels Creek through a variety of means: <br />1. An oxidation reaction in which dissolved zinc is exposed to oxygen as it flows down the <br />tunnel or creek and becomes zinc hydroxide, which is basically not soluble. This is <br />particularly likely given the residence time provided by the ten partial cave -ins found along <br />the Revenue Tunnel between the Atlas Drift and the Yellow Rose Drift at the time the <br />samples were taken. They act as check dams and rock filters for the mine water flow. Also, <br />Sneffels Creek is flowing rapidly to a steep grade and will oxidize readily. Organic material <br />in the Revenue tunnel, such as numerous old timbers, is known to help precipitate zinc, <br />especially at neutral pH levels. <br />2. Zinc is not a naturally soluble element in pH neutral water. The Sneffels Creek water <br />samples are all pH 7.0 to 8.4. Although zinc is slightly soluble at this pH, many interactions <br />can take place to help it drop out. The data shows that zinc is dropping out over the course <br />Revenue Mine August 2012 T - <br />