2017-02-03_PERMIT FILE - C1980004 (21)

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PROBABLE HYDROLOGIC CONSEQUENCES EAST SALT CREEK -SURFACE & GROUND WATER LEACHATE AND MINE WATER METAL ANALYSIS In addition to the prior demonstration showing no loss of production by adding mine water and leachate to East Salt Creek during irrigation season, the Colorado Division of Wildlife (DOW) requested additional information (as part of TR -16 adequacy response #3, item #52) specific to the impact of adding mine water and leachate to the surface waters of East Salt Creek. In particular, if the heavy metals in the mine water and leachate will be detrimental to wildlife utilizing the waters. The DOW suggested evaluating East Salt Creek monitoring points above and below McClane Canyon mine and suggested analyzing the waters for heavy metal concentrations. Data has been gathered quarterly for the surface waters of East Salt Creek as part of the Annual Hydrologic Report required by the DRMS, over the last several years. The monitoring points that are applicable to the DOW's request are SW -1 which is above McClane creek and SW -8 which is above Munger Creek. The data evaluated for SWA and SW -8 is an average of the values recorded during all four quarters over a five year period and the summary is shown in Table N-8. It's important to note, data from SWA and SW -8 should be evaluated individually, as each monitoring point has its own individual site characteristics and it is not accurate to assume the parameters that correspond to SWA should equal the parameters at SW -8. SWA is approximately one mile upstream from SW -8 and between the two points there are two large fields that are irrigated and could contribute to differences in sample results, or in general, mobilization of metals and other analytes from the soils in the channel of East Salt Creek. In response to the DOW's concerns regarding leachate from the coal mine waste pile and sediment pond, the Operator performed a Toxicity Characteristic Leaching Procedure (TCLP) test. A TCLP test is a soil sample extraction method for chemical analysis used to simulate leaching through a landfill. Obviously the Coal Mine Waste Pile is not a landfill, but the Operator believes the leaching mechanism of the TCLP methodology is applicable to the potential leachate from the gob pile and sediment pond. As discussed in detail on page 3, a coal mine waste pile is planned for the area south of the office. The coal mine waste pile has a footprint of 13.2 acres, and the potential leachate flow calculated previously, including leachate from the sediment pond is 0.69 gpm (0.001 cfs). Flow from East Salt Creek in the last five years has been between 0 cfs and nearly 10 cfs, with the Creek being dry only in the 3rd and 4th quarters of 2009. The flow from leachate is insignificant when compared to the flows in East Salt Creek, even when East Salt Creek is dry the combined flow from the leachate is essentially zero. Table N-7 presents a TCLP analysis of coal refuse from the existing Coal Mine Waste stockpile. The TCLP, is designed to determine the mobility of both organic and inorganic analytes present in liquid, solid, and multiphasic wastes. This data will represent the Appendix N — PR -02 -11 - 10/10