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Peabody Sage Creek Mine <br />SL -3 Phase III Bond Release Request <br />July 2014 <br />excursion on Fish Creek was not caused by either mining operation. Also, nitrites are unstable in <br />aerated water (Hem, 1989), and will oxidize to nitrates. <br />Six out of thirty six samples from NPDES4 exceeded the chronic selenium standard of 4.6 ug /1, <br />with values ranging between 4.9 and 14 ug /1. The potentially dissolved (PD) method for <br />measuring selenium levels is required for NPDES compliance. The dissolved (D) selenium <br />method is used for assessing stream compliance and was also sometimes run as a quality control <br />check. The total recoverable (TR) selenium method was run as a quality control check. Three of <br />the six PD excursions had TR values that were less than the PD values, which indicates possible <br />matrix interference with the PD method. The three TR values in those cases were all less than 4.6 <br />ug /1. The acute standard, 18.4 ug /1, was not exceeded in the PD form. No selenium exceedances <br />occurred at any surface water sites downstream of NPDES4, including lower Fish Creek Site <br />SSF13 so attainment is being met downstream <br />PSCM discharges surface runoff and spoil leachate into Segment 13e (Grassy Creek and <br />tributaries) of the Yampa River based on Colorado Water Quality Control Commission <br />(CWQCC) Regulation 33. PSCM is required to monitor 17 parameters in that segment per its <br />CDPS and CDRMS permits, which is provided in Table 8. Table 9 provides a statistical summary <br />of the water quality over years 2011 to 2013 for PSCM's Outfall NPDES2 and Stream Sites <br />SSG1, SSG2 and YSG5. Table 10 provides a comparison of those data with the Segment 13e <br />standards. <br />Table 10 indicates the pH standard was exceeded once at Site SSG2 with a value of 6.44 on <br />6/3/13. The pH values upstream at Sites NPDES2, NPDES3 and SSG1 on the same day were <br />7.56, 8.31 and 7.57, respectively. The pH value downstream at Site YSG5 on the same day was <br />8.35 so the exceeded value appears to be in error. <br />Table 10 also indicates the total recoverable (TR) iron standard of 1.0 mg /l was exceeded a total <br />of eleven times (out of 27 samples) at Grassy Creek Sites SSG1 (Grassy Creek upstream of <br />PSCM outfalls), SSG2 and YSG5 (both are Grassy Creek sites downstream of PSCM outfall). <br />High TR iron values are normally associated with high total suspended solids. No excursions of <br />27 <br />