Laserfiche WebLink
The data demonstrates that there is a distinct difference between concentrations before and after the pond was <br />drained. It is seen that iron, lead and zinc increased after the mine water pond was drained and the mine water <br />was diverted around the pond and was discharged directly into Sneffels Creek. After the pond was drained, the <br />water in the seep consisted of only a minor amount of excess mine water that did not fit in the diversion pipe, but <br />also natural groundwater and water from the old waste piles. This indicates that the natural groundwater from <br />the Revenue Pile is higher in iron, lead and zinc than the mine water but lower in cadmium. The seep data will be <br />used in comparison with the results from the groundwater wells and is used to contribute to the proposed <br />standards. This is important because there is a large amount of historical data available forthe seep afterthe pond <br />was drained -totaling 11 samples since June of 2013. <br />Chapter 4 - Groundwater Wells <br />In the early summer of 2014, three groundwater well locations were installed for monitoring near the Revenue <br />Mine. The locations of each of the three well locations are shown below in Figure 3 and they were chosen to be <br />downstream of the Revenue tailings pile and the Atlas tailings pile so that we could identify if any poor water was <br />emanating from the piles or from any other activity upstream from the piles. During installation of these wells it <br />was revealed that there were actually two distinct ground water levels at each location, a well was installed in <br />both groundwater levels at each location. These are referred to as the shallow and deep wells at each location. <br />There are 6 total well waters that are being sampled. The two water levels were separated by a clay type zone <br />that was primarily impervious but there is no way to know if this clay zone is consistent over the entire permit <br />area. These wells were sampled on June 10, 2014 at both shallow and deep depths. The wells were re- sampled <br />on July 22, 2014, representing the baseline condition of the groundwater levels before any new tailings are placed <br />at the mine site. Additional sampling occurred on December 4th, 2014 and February 13th, 2015. It must be noted <br />that the areas above the GW -1 well site has some past contamination from the old Atlas tailings pile and the areas <br />above wells GW -2 and GW -3 have contamination from the old Revenue waste rock pile, which also contains waste <br />3 <br />Dissolved Cadmium (mg /L) <br />Dissolved Lead (mg /L) <br />0.00025 <br />0.005 <br />0.0002 <br />0.004 <br />0.00015 <br />0.003 <br />0.0001 <br />0.002 <br />0.00005 <br />0.001 <br />0 <br />0 <br />Average Before Average After <br />Average Before Average After <br />Total Iron (mg /L) <br />Dissolved Zinc (mg /L) <br />0.8 <br />0.2 <br />0.6 <br />0.15 <br />0.4 <br />0.1 <br />0.2 <br />0.05 <br />0 <br />0 <br />Average Before Average After <br />Average Before Average After <br />Figure 2: Comparison of Seep (SW -3) Before and After Mine Water Pond Drainage for Target Contaminants <br />The data demonstrates that there is a distinct difference between concentrations before and after the pond was <br />drained. It is seen that iron, lead and zinc increased after the mine water pond was drained and the mine water <br />was diverted around the pond and was discharged directly into Sneffels Creek. After the pond was drained, the <br />water in the seep consisted of only a minor amount of excess mine water that did not fit in the diversion pipe, but <br />also natural groundwater and water from the old waste piles. This indicates that the natural groundwater from <br />the Revenue Pile is higher in iron, lead and zinc than the mine water but lower in cadmium. The seep data will be <br />used in comparison with the results from the groundwater wells and is used to contribute to the proposed <br />standards. This is important because there is a large amount of historical data available forthe seep afterthe pond <br />was drained -totaling 11 samples since June of 2013. <br />Chapter 4 - Groundwater Wells <br />In the early summer of 2014, three groundwater well locations were installed for monitoring near the Revenue <br />Mine. The locations of each of the three well locations are shown below in Figure 3 and they were chosen to be <br />downstream of the Revenue tailings pile and the Atlas tailings pile so that we could identify if any poor water was <br />emanating from the piles or from any other activity upstream from the piles. During installation of these wells it <br />was revealed that there were actually two distinct ground water levels at each location, a well was installed in <br />both groundwater levels at each location. These are referred to as the shallow and deep wells at each location. <br />There are 6 total well waters that are being sampled. The two water levels were separated by a clay type zone <br />that was primarily impervious but there is no way to know if this clay zone is consistent over the entire permit <br />area. These wells were sampled on June 10, 2014 at both shallow and deep depths. The wells were re- sampled <br />on July 22, 2014, representing the baseline condition of the groundwater levels before any new tailings are placed <br />at the mine site. Additional sampling occurred on December 4th, 2014 and February 13th, 2015. It must be noted <br />that the areas above the GW -1 well site has some past contamination from the old Atlas tailings pile and the areas <br />above wells GW -2 and GW -3 have contamination from the old Revenue waste rock pile, which also contains waste <br />3 <br />