2013-02-08_REPORT - C1981019 - Laserfiche WebLink

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Page 2 of 3 • For the reporting year of the 2011 AHR (which is the 2011 calendar year), at surface water sites UWFGSC and LTC concentrations of several parameters reached the maximum values of the entire recording period. For UWFGSC the period of record for water quality data collection is since 2007, and for the LTYC site the period of record extends back to 1983. For example, TDS at LTC was 2910 mg /1 on November 10, 2011. The Division has the following observations regarding groundwater data (no direct response is required from Colowyo although these comments are related to comment number 3 above): • Per the RZ values for groundwater, there are some significant trends in the data. In the A -7 well dissolved Iron has been increasing, and in the Gossard well TDS has been increasing over the entire period of record, although it has been decreasing since 2006. • Even though dissolved Iron has been increasing in the A -7 well, it has never reached levels of concern. The maximum value in this well was 0.1 mg /1 on August 17, 2011. The CDPHE agricultural standard for dissolved Iron in groundwater is 5 mg /1 (CDPHE Regulation 41). • In past years, high values have been reported in groundwater for Iron (maximum of 29 mg /1 at the Gossard well, 8 October 1998) and for TDS (maximum of 2330 mg /1 at MT- 95 -02, 17 March 2009). 6. Data from DMRs was not provided in the AHR, but a review of this data is an important aspect of water quality at the Colowyo Mine. I reviewed this data (in DMR reports submitted by Colowyo) and found the following exceedances of regulatory limitations. • First quarter: At Outfall 007A, a Total Recoverable Iron concentration of 2.83 mg /1 (exceeding the limitation of 1.0 mg /1) was measured on March 1, 2011. A waiver of primary standards was made to CDPHE, and evidence was provided that the exceedance was due to snowmelt. The alternate limitation for settleable solids was met. • Second quarter: • Colowyo's surface water monitoring activity revealed exceedances of primary effluent limitations in April at three locations (Outfalls 001A, 004A, and 007A). Meteorological data provided by Colowyo to the Division suggests that the runoff during the exceedances of April was due to snowmelt. Furthermore, the alternate limitation for settleable solids was met at all three locations. CDPHE was informed of the exceedances. • At Outfall O10A (discharge from East Taylor Pond) discharge limitations were exceeded for Total Suspended Solids and Total Recoverable Iron in June. Alternate limitations were not applicable to these exceedances. Recent dredging of this pond should help reduce future exceedances. • Regarding East Taylor Pond, Colowyo has attempted to use spoil spring activity to invoke alternative limitations. However, it is my understanding that spoil spring activity is not considered grounds for a waiver of limitations. If you disagree, please explain your rationale. • Third quarter: At Outfall O10A discharge limitations were exceeded for Total Suspended Solids in July. Alternate limitations were not applicable to these exceedances. Recent dredging of this pond should help reduce future exceedances. • Fourth quarter: At Outfall O10A discharge limitations were exceeded for Total Suspended Solids in October. Alternate limitations were applicable to these exceedances per Colowyo. No direct response is required from Colowyo, although a discussion of spoil spring activity as it relates to waiver limitations is requested (last bullet under second quarter).