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Comments Submitted by Denver Water <br />August 20, 2010 <br />9. Table A-9. How was the mass loading in lbs/day determined for Radium 226 & 228 if the <br />conversion from pCi/L to ug/L is unknown? Verify that the loading is calculated <br />correctly. <br />10. Determination of Baseline Water Quality (BWQ). In this instance, the use of <br />downstream water quality is inappropriate for the determination of baseline water quality <br />because it is influenced by decades of mining and recently failed reclamation approaches. <br />A BWQ determination based on upstream water quality would have a significant impact <br />on the magnitude of the term SCT, Significant Concentration Threshold. <br />11. Determination of ADBAC Concentrations. Similar to comment 5. The mass balance <br />equation in this section is appropriate for a single point of discharge. Consider the <br />appropriateness of this equation for the multiple points or areas of discharge. The <br />ADBAC concentration needs to be re-calculated based on 1) a correctly determined value <br />of SCT (SCT should be based on upstream BWQ) and 2) would be different if there <br />were additional terms in the mass balance calculation incorporating pollutant loadings <br />from the mine pool, seeps, and waste rock pile areas. If WQCD believes that information <br />does not exist to expand the terms of the mass balance, it would be appropriate to require <br />the permittee to acquire this information and submit it in response to a compliance <br />schedule requirement incorporated into the permit. <br />CDPS Permit No. CO-0001244 <br />1. Part I A (2 reQardina the number of outfalls. Only one outfall is identified when at least <br />two treatment needs are known; 1) treatment of sumps and alluvial water and 2) treatment <br />of mine pool water. Have effluent limits been properly prepared considering both needs <br />or will there be multiple outfalls? Has the permittee requested only one outfall or <br />identified that both needs will be addressed by one treatment system and one outfall? <br />Will runoff and stormwater be routed to the same outfall or need a separate outfall?