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Rule 3.03.2(2) requires the Division to evaluate hydrologic impacts prior to releasing reclamation <br />lability. This evaluation must consider whether pollution or surface or subsurface water is occurring <br />and the probability of future occurrence with such pollution. The Division's evaluation is <br />summarized below. <br />Ground Water Impacts <br />Colowyo maintains three wells in the surrounding area of the SL -12 reclamation parcels that have <br />been monitored: the North Good Spring Well, the Gossard Well and A-6 Well. The A-6 and <br />Gossard Wells represent the ground water conditions up and downgradient from the mining areas <br />while the North Good Spring Well represents conditions immediately below the mining area in the <br />Section16 Pit. <br />The North Good Spring Well is an alluvial well located immediately down gradient of the SL -12 <br />parcels in the Section 16 Pit area. Observations of the data from the well indicate that over time, <br />water elevations have slightly decreased beginning around 2003 as shown in Figure 6 of the SL -12 <br />application. However, this slight decreasing trend occurs after the Section 16 Pit reclamation period <br />and coincides with the reclamation period for the East Pit as well as predictions within Colowyo's <br />PAP. It was also observed in the North Good Spring Well that over time TDS and conductivity has <br />increased slightly as well. However no concentrations of analytes, including TDS, have increased <br />to levels that are cause for concern and are within the range predicted within Colowyo's PAP. <br />Any ground water in alluvial deposits in the bond release area meets the classification of Limited <br />Use and Quality because the alluvial water is of such small volume and is unlikely to be used in the <br />future. The Basic Standards for Ground Water have no water quality standards for the Limited Use <br />and Quality classification. <br />Surface Water Impacts <br />All of the runoff from the SL -12 areas flow into either the Section 16 or Gulch A Pond. Both of <br />these ponds are inspected on a regular basis by the Division as well as quarterly by Colowyo. The <br />Section 16 and Gulch A Ponds have been found to be in good repair and properly functioning. None <br />of these ponds are included in the SL -12 Bond Release application. Both ponds are associated with <br />outfalls in the Colorado Discharges Permit System permit number CO -0045161. Exceedances of <br />discharge limitations that have not been the result of runoff (when alternate limitations were in <br />effect) have been very rare and not indicative of a threat to water quality. <br />Findings on Protection of Hydrologic Balance <br />Based on the foregoing observations, the Division finds that the Colowyo Mine has minimized <br />disturbance of the hydrologic balance in the SL -12 bond release area and prevented material <br />damage outside the permit area. The Division also finds that Colowyo Mine has not caused <br />hydrologic changes that adversely affect the approved post mining land use in the permit area. <br />Proposed Decision and Findings of Compliance December 2017 <br />Partial Phase II and III Bond Release SL -12 Page 7 <br />