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Rationale-Reconenzendation forApproual July 26, 2000 Page 6 contaminants that may be released in the long and short term from the VLF during and after the active mining and leaching. Clearly, there is no discussion of costs to treat planned released from the VLF after puncturing, if the dischazge contain pollutants other than WAD CN at 0:? mg/L. (Roger Flynn: CFV, Kirby Hughes) DMG Response: Detoxification and monitoring covering this issue were approved under Amendment No. 7. The previously Board approved detoxification and monitoring practices have been expanded to address the areas covered under Amendment No. 8. The practices sufficiently address concerns regarding compliance with water quality standards. 15. Both exceedances [WAD CN and Zn standards] were explained as upset conditions as a result of heavy precipitation. However, the 1999 rain and snowmelt levels were below the 100-year, 24-hour event, suggesting [hat exceedances are likely to happen again. Rule 3.1.36(b) requires compliance with applicable federal water quality laws & regulations. (J. Lockhart) DMG Response: The finding of "upset condition" at issue was determined by CDPHE under the authority of the Colorado Water Quality Control Act. According to the permit amendment application, exceedances of Zn might be encountered during future upset conditions. If exceedances do occur to surface water, CDPHE is the responsible regulatory agency. 16. Due to release of pollutants from the Carlton Tunnel, and the high likelihood of future releases from the same, the applicant must provide adequate water treatment at this location. Since the Carlton has been shown to be a source of water pollution, and the applicant's permit covers the majority of the diatreme, the applicant must take full responsibility for the water that comes out of the Tunnel. Without water treatment, the discharge from the tunnel will not meet water quality standards. Therefore, the permit amendment application must be denied. (Mineral Policy Center) DN1G Response: Past discharges from the Carlton Tunnel have not required water treatment to maintain compliance with the Colorado Water Quality Control Act. The Cresson Operation has maintained an NPDES permit and has been in compliance since operations began. Based on this past performance, the notion that [here is a high likelihood of future releases being out of compliance with standards cannot be sustained. 17. The hydrogeochetnical model used in the application does not cover the likelihood of current and future preferential flow through the diatreme. (Mineral Policy Center) DMG Response: The hydrogeochemical model actually depends on preferential flow through carbonate lined fractures to bring potentially acidic waters in contact with those cazbonates. Therefore, the Division does not anticipate changes to water quality. l8. Monitoring of the entire suite of chemicals should be required. (J. Minkler; R. Flynn; R. Fay; K. Hughes) DhfG Response: Water quality monitoring parameters are derived from a mineralogical and water quality assessment. Parameters are selected based on their ability to record a pollutant discharge or to indicate changes in chemical behavior of the system in order [o prevent a discharge of pollutants. Because the ores and waste rock contain only a select number of potential pollutants, the Division does not consider it necessazy to monitor for all regulated pollutants.