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Tuble 2: Outlier Parameters and Data Points from the December 41h, 2014 Sampling Date <br />Parameters <br />Units <br />12/4/2014 Concentration <br />GW- <br />1A <br />GW- <br />1B <br />GW- <br />2A <br />GW- <br />26 <br />GW -3A <br />GW -313 <br />Aluminum, total <br />mg /L <br />2.73 <br />1.06 <br />3.38 <br />0.85 <br />23.4 <br />0.73 <br />Cadmium, total <br />mg /L <br />0.0003 <br />0.0002 <br />0.001 <br />0.0002 <br />0.0054 <br />0.0001 <br />Copper, total <br />mg /L <br />0.12 <br />Cyanide, total <br />mg /L <br />Iron, total <br />mg /L <br />3.4 <br />1.39 <br />4.34 <br />1.09 <br />23.7 <br />1.61 <br />Lead, total <br />mg /L <br />0.0497 <br />0.0124 <br />0.12 <br />0.0071 <br />2.17 <br />0.0103 <br />Mercury, total <br />mg /L <br />0.0003 <br />Residue, Non - Filterable (TSS) @105C <br />mg /L <br />50 <br />7 <br />57 <br />12 <br />320 <br />22 <br />Zinc, total <br />mg /L <br />0.12 <br />0.1 <br />0.65 <br />0.29 <br />2.13 <br />0.11 <br />Although the exact cause of this outlier data is unclear, there are a couple possible explanations. One potential <br />explanation is that it was caused by the well sampling technique being used. Before sampling each well was <br />purged using bailers which could have potentially disturbed settled solids at the bottom or sides of the wells. <br />After the December 2014 sample date a new system was introduced to purge the wells using a pump to <br />minimize this impact. Another potential explanation could be due to installation errors in the wells, more <br />specifically in well number 3. This is suspected due to the significantly higher measurements in that particular <br />well. However, because there is only one outlier date it is difficult to exactly define the source of the increase of <br />these parameters. <br />Chapter 7 - Proposed Standards <br />Three different aspects were taken into account to develop the final proposed standards. These aspects include <br />a) the representative groundwater value determined from the sampling wells, b) the in- stream water quality <br />standard set by the methodology in the CDPHE discharge permit, and c) the CDPHE groundwater standards which <br />are used in some cases as a backup method to determine standards for parameters when the other methods don't <br />provide the information. <br />In- Stream Standards <br />The methodology used to determine CDPHE discharge permit limitations was from CDPHE Regulation Number 35 <br />on stream classifications and water quality standards for the Uncompahgre River Basin, Stream Segment Number <br />9 [1]. These regulations are referred to as in- stream standards as they are specific to the stream segment <br />applicable to the Revenue Mine site. The values as defined in the numeric standards table for Regulation No. 35 <br />are shown below in Figure 4. <br />M <br />