2008-02-08_PERMIT FILE - M2007044 (2)

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The quantity of water that will be pumped will be reported to DBMS as indicated in Section 10 of Exhibit T, both in the original text and the revised text that is included as Attachment A to this response. This information is also required by our discharge permit and conditional water right. As discussed later in our response to Russ Means' comments, these reports to other agencies will also be copied to DRMS. 3) Pg. b. Applicant states that "drinking water standards do not apply to mine water discharge. " Please provide the rationale for• this statement. Is applicant implying that the mine discharge is sr fficiently distant from any drinking tivnter• intake that the site specific conditions allow this generalization, or• is the applicant citing a specific regulation? Additionally, applicant contradicts this assertion by presenting a rationale for why sulfate, for which the only regulatory limit relates to drinking water; will not exceed its regulatory limit of 250 mg/L. Water discharge standards are based on the use of the water. Surface water standards apply to surface water discharge and, in this case, the state standards for Segment 3A of the Dolores River Basin apply. Our discharge standards have been designed to be protective of the water uses for this river, which include recreation {Class E}, agriculture, and warm water aquatic life (Class 2}. This water is not used for domestic drinking water; therefore, the Water Quality Control Division did not include drinking water standards in the regulations for the lower Dolores River Basin (Regulation No. 3S) and our discharge permit. You are correct in stating that the only regulatory limit for sulfate in Colorado is a drinking water standard. The same is true for chloride. This was my mistake, as I had believed they were included in the Water Quality Control Commission's basic surface water standards (Regulation No. 31). They are not; however, these regulations do include a chronic aquatic standard of 1 mg/L for iron, which we will include as a regulatory limit in our reporting to DRMS. We have implemented analysis for dissolved iron in our treatment plant discharge. The initial analysis indicated that iron was nondetect at a method detection limit of 0.030 mg/L. 4) Pg. 7. Applicant states that the probability of contaminating the strata beneath the waste rock piles and other surface facilities is "virtually nil" because of the low perrneabiliry and extensive thickness of the intervening mndstones. I~er•tical permeability values in the range of 10~~ t 10-11 cna/sec ar•e referenced. DBMS acknowledges this, but reminds applicant to be cognizant of the potential for fracture flow beneath those facilities, in which case a downg-•adient monitoring well is clearly justified. Agreed. 5) Pg. 7. In reference to the proposed monitoring well, applicant states "if the lower Brushy Basin sandstones are not present, the boring will be abandoned..... " DRMS suggests that the monitoring well be installed even under such conditions, providing ground water is encountered. Even completing the well in the Salt Wash Formation, 2