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George V. Patterson, Energy Fuels Coal, Inc. <br />Page 12 <br />February 12, 2015 <br />monitoring plan described in Exhibit 25. This data should be used in a detailed analysis of <br />the impact of the Southfield Mine on groundwater quantity. The analysis should also <br />include the data collected from the other groundwater monitoring points and be used to <br />validate any modeling conclusions. (If it is determined that MWNW must be replaced, the <br />Division would appreciate the opportunity to discuss an alternative location for the new <br />monitoring well) <br />ii) Please clarify the lowest elevation that could be measured if MWNW were clear, and <br />whether or not this is the floor of the mine, (5855' was the elevation discussed in TR35 <br />adequacy correspondence and given on page 2.05.6 -53 of the PAP; 5860.5' was used in the <br />2013 Summary Report by BBA) <br />iii) Please provide a discussion of well MW16 explaining the fact that the recorded water level <br />dropped below 120' below ground surface (bgs) numerous times between 1979 and 2000, <br />but that since 2000 the well has often been reported as dry with the depth to water <br />indicated as 110' bgs (according to Exhibit 25, the depth of MW16 is 136' and the <br />screened interval is from 106'- 136'). <br />d) Impacts to Groundwater QualitX <br />The PHC section of the PAP predicts the following impact to groundwater quality: <br />• Potential increases in the levels of TDS and concentrations of specific chemical <br />constituents <br />Groundwater at the Southfield Mine has a neutral pH and is of a weak sodium sulfate type, with <br />relatively high levels of Total Dissolved Solids (TDS) and iron. Background water quality data is <br />summarized in table 13 of the PAP and is reproduced below, for quick reference (Table 2). <br />The question of applicable water quality standards was discussed extensively in the June 2013 <br />Memo, where it was determined that water in Southfield's flooded mine workings, as well as water <br />in coal or low permeability rock interbedded with coal down - gradient of the flooded mine <br />workings, does not need to meet drinking water standards, since the ambient water quality does not <br />meet these standards. Additionally, the June 2013 Memo highlighted the fact that the Colorado <br />Division of Water Resources recognizes that groundwater obtained from coal zones is known to be <br />of degraded quality and advises against completing wells for domestic or agricultural purposes in <br />these zones. To illustrate this point further, Table 2 shows the baseline groundwater quality data <br />from the permit with the most stringent water quality standards taken from Tables 1 -4 of Regulation <br />41 for reference." Parameters where the baseline data exceeds the standard are shown with a red <br />fill. It should be noted that the background data shows a great deal of variation in parameter values. <br />The approved baseline data is apparently the aggregated result of sampling from multiple wells. It is <br />not possible to parse the data to find up- gradient and down - gradient water quality, (presumably the <br />determination was made that background groundwater quality in the area was generally variable <br />and poor), neither is it possible to use the baseline data as a starting point to analyze water quality <br />trends. <br />