|
COLORADO DEPARTMENT OFPUBLICHEALTHAND ENVIRONMENT, Warer Quality Control Division
<br />Rationale -Page 12 Permit No. CO-00327!5
<br />VII. REFERENCES
<br />A. "Basic Standards and Methodologies for Surface Water ", Regulation No. 31, Colorado Wafer Quality Control Commission,
<br />effective October 30, 1001.
<br />B. "Classifications and Numeric Standards for Lower Colorado River Basin ", Regulation No. 37, Colorado Water Quality
<br />Control Commission, effective January 20, 2004.
<br />C. "Colorado Discharge Permit System Regulations ", Regulation No. 61, Colorado Water Quality Control Commission,
<br />effective June 30, 2003.
<br />D. "Regulations for Effluent Limitations", Regulation No. 62, Colorado Water Quality Control Commission, effective December
<br />30, 1998.
<br />E. "Colorado Total Maximum Daily Load and Wasteload Allocation Guidance ", Colorado Department ofPublic Health and
<br />Environment, Water Quality Control Division, effective November 1991.
<br />F. "Colorado River Salinity Standards ", Regulation No. 39, Water Quality Control Commission, effecttve August 30, 1997.
<br />G. "Antidegradation Significance Determination for New or Increased Water Qua[iry Impacts, Procedural.Guidance, "
<br />Colorado Department of Public Health and Environment, Water Quality Control Division, effective December 2001.
<br />H. "Determination of the Requirement to Include Warer Quality Standards-Based Limiu in CDPS Permits Based on
<br />Reasonable Potential Procedural Guidance, "Colorado Department of Public Health and Environment, Water Quality
<br />Control Division, effective December 2002.
<br />I "The Colorado Mixing Zone Implementation Guidance, "Colorado Department of Public Health and Environment, Water
<br />Quality Control Division, effective Apri12002.
<br />J. Colorado Department ofPublic Health and Environment, Water Quality Control Commission. Regulation No. 39 Colorado
<br />River Saliniri Standards (S CCR 1002-39). Denver: CDPHE, as revised 7/14/97 and effective 8/30/97.
<br />K US Government, Office of the Federal Register, National Archives and Records Administration. Code ofFedera7
<br />Relations /Part 4341. Washington: 1002.
<br />VIII. PUBLIC NOTICE COMMENTS
<br />The permittee submitted comments. The responses will be addressed in the order of the permittee's letter.
<br />1. The draft permit applies pH limiu of 6.5 to 9.0 s.u. to all outfalls year-round. The permittee requested that previous seasonal
<br />upper limits of 9.5 s.u., applicable to outfalls 001, 002, and 005, and new outfa11020, be continued. For prior permits, our
<br />Division made a decision to place a pH limit on the discharge (pH in the range of 6.5 - 9.5 s. u.) that was higher than the
<br />applicable water-quality standard (pH in the range of 6.5 to 9.0 s.u.) and that this decision was based on a favorable
<br />consideration that the permittee was restricted from using chemicals to control algal growth (indirect cause of high pH
<br />values during warmer months) in the ponds by the Colorado Division of Minerals and Geology. This decision was
<br />reviewed during the preparation of this fifth renewal of the permit and reversed. Dur Division's mission is to implement limits
<br />in permits for discharges thatprotect the water-quality standards set for the receiving water. Historically, As noted in
<br />Tables VI-1, VI-2, and VI-4 of this Rationale, the pH levels in the discharges have been below 9.0 s.u. Given this past
<br />performance and the statement in the permitree's lever (April 7, 2004) that there is no evidence that the pH conditions
<br />at these outjalls will change, there is a reasonable basis to predict that the lower pH limit in this renewal permit will not be
<br />exceeded.
<br />2. The permittee objected to the proposed change in the reporting frequency for Discharge Monitoring Reporu (DMR) from
<br />quarterly to monthly. The permittee noted that they have 19 outfalls and that this change would be quite burdensome,
<br />requiring over a three fold increase in labor hours for them to comply. The Division agrees, and will not change the
<br />reporting frequency. The DMR reporting frequency shall remain at quarterly.
<br />3. Thepermittee noted that there is an incorrect reference in the draft rationale on page 9 to WET testing for outfal7 002. A s
<br />this ouffall no longer discharges mine water, WET testing requirements no longer apply. The reference has been removed.
<br />Jon Kubic
<br />Aprill8, 2004
<br />Lnst Revised: 4/19/1004
<br />
|