2012-07-25_GENERAL DOCUMENTS - C1981019

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indicate that over time TDS and conductivity have increased somewhat. Also, TDS is higher in this well than in the wells above the East Pit area (A6 and A7). However no concentrations of analytes, including TDS, have increased to levels that are cause for concern. TDS values have only rarely risen above 2,000 mg/l and have generally only been slightly above (less than 120 percent of) values measured prior to the 1990s. Small increases in TDS are in agreement with the expected probable hydrologic consequences of mining listed in the PAP. In the West Pit area there are no alluvial wells in the vicinity of the former pit and SL-05 reclamation area. Per initial Colowyo hydrology reports (e.g., the PAP includes a 1979 report by Leonard Rice Consulting Water Engineers), there was never a significant possibility of groundwater contamination from mining in this area, and there is no reason to believe that groundwater contamination has occurred. Any ground water in alluvial deposits in the bond release area meets the classification of Limited Use and Quality because the alluvial water is of such small volume and is unlikely to be used in the future. The Basic Standards for Ground Water have no water quality standards for the Limited Use and Quality classification. The PHC section of the Colowyo permit states that there will be a slight decrease in the water elevation. Data from the NGS Well closely follows this predicted trend. Surface Water Impacts All of the runoff from the SL-05 areas flows into one of the following sediment ponds: Streeter Pond, the Gulch A Pond, or the West Pit Pond. All of these ponds are inspected on a regular basis by the Division as well as CCC. All of these ponds have been found to be in good repair and properly functioning, although routine maintenance is occasionally required. None of these ponds are included in the SL-05 Bond Release application. Recent Division reviews of AHRs and DMRs indicate that there have been no significant water quality problems at the discharge points associated with these ponds. All three ponds are associated with outfalls in Colorado Discharge Permit System permit number CO-0045161. Exceedances of discharge limitations that have not been the result of runoff (when alternate limitations were in effect) have been very rare and not indicative of a threat to water quality. There are eight stock tanks located in the Phase III Bond Release area (A, B, C, D, E, F, L and M). CCC has provided written documentation that:  The criteria for permanent impoundments have been met pursuant to Rule 4.05.9(13).  These stock tanks are acceptable to the State Engineer’s Office.  The landowner has requested that the stock tanks remain as permanent structures. CCC has submitted a technical revision to the permit to include the stock tanks as permanent structures (TR-89). This technical revision was approved by the Division on March 18, 2011. Proposed Decision and Findings of Compliance 25 July 2012 Partial Phase III Bond Release Sl-05 Page 8