2014-01-14_REPORT - C1981019 (3)

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L Mr. Rob Zuber January 8, 2014 Page 2 DRMS Item 4: The Division has the following observations regarding groundwater data (no direct response is required from Colowyo although these comments are related to comment number 2 above): • Per the R` values for groundwater, there is one .significant trend in the data. In Gossard well. TDS has been increasing over the entire period of record although it has been decreasing since 2006. Recent values have been approximately 1, 700 mgjl. • For the reporting year of the 2012 AHR, in one of the wells concentrations of two parameters reached the maximum values of the entire recording period. In the Mfi 95 -02 well, sulfate (1, 090 mg/l) and sodium (181 mg /1) were at all -time highs (the period of record for this well is 1984 to 2012), but there is not a significant long -term trend for either parameter in this well. • The high sulfate value mentioned above is higher than the domestic drinking water standard. As there are domestic wells in the area, this may become a concern if levels of this parameter continue at this level or rise in the future. Response: No response required. DRMS Item 5: 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 D SIR reports submitted by Colowvo) and found the following exceedances of regulatory limitations (CDPHE was informed of the exceedances). • First quarter: At Outfalls 001A, 004A. 007A, 010A, and 011A exceedances of limitations for TSS and Total Recoverable Iron were detected. (High TSS values were not detected at Outfall 010A). A request for waiver of primary standards was made to CDPHE, and evidence was provided that the exceedances were due to snowmelt. The alternate limitation for settleable solids was met at all outfalls. • Second quarter: • At Ou fall 010A (discharge from East Taylor Pond) the discharge limitation was exceeded far Total Suspended Solids in June. Alternate limitations were not applicable to these exceedances. It is believed that algae in the pond are the problem, and Colowyo has committed to cleaning the pond to prevent future exceedances. • At Ou6tal101 ]A (discharge from West Tavlor Pond) the discharge limitations were exceeded for Total Suspended Solids and Total Recoverable Iron in March 2012. Colowvo indicated that alternate limitations were applicable due to snowmelt runoff (precipitation data support this assertion), and the Settleable Solids limitation was not exceeded • Third quarter: At Outfall 010A discharge limitations were exceeded for Total Suspended Solids in July 2012. Alternate limitations were not applicable to these exceedances. • Fourth quarter: No discharge limitations were exceeded Response: No response required. DR,WS Item 6 Regarding Rule 4.05.13(4)(c): in Subparagraph (i) the word "quality "should be "quantity, " and in Subparagraph (ii) the word "three " in the first sentence should he 'four. " Response: Both revisions as noted in the comment have been corrected and will be submitted in the 2013 AHR. AN EQUAL OPPORTUNITY I AFFIRMATIVE ACTION EMPLOYER A Touchstone Enemy" Cooperarive