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<br /> <br />COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division <br />Rationale - Page 11. Permit No. CO-0032115. <br />VI. TERMS AND CONDITIONS OF PERMIT <br />a) Active Mining - all discharge points: <br />Limitations for pH and oil and grease apply to all discharges, <br />regardless of precipitation conditions. Additionally, TSS and <br />total iron samples should always be taken. It the results of <br />the analyses exceed the permit limit, the permittee may submit <br />documentation proving that the discharge was precipitation <br />induced. The proof of the size of the precipitation event <br />consists of: <br />(1) rain gauge data or the volume of water contained in the <br />snow, based upon calculations from actual snow samples; <br />(ii) the sample results for TSS, iron, pH, settleable solids and <br />oil and grease; and <br />(iii) influent/effluent metered flow. <br />It is only upon acceptance by the Division of said proof that <br />the settleable solids limitation will apply in place of the TSS <br />and total iron limitations for precipitation events that are <br />less than or equal to the 10-year, 24-hour storm event. Failure <br />to submit the required information will result in the denial of <br />the exemption by the Division. <br />Similarly, for precipitation events greater than the 10-year, <br />24-hour event (or equivalent snowmelt volume), proof of the size <br />of the storm will consist, again, of (i)-(iii), above. Upon <br />acceptance of proof that discharge was caused by precipitation, <br />compliance with TSS, total iro^ and settleable solids <br />limitations will be exempted. This means such a discharge would <br />be subject to pH and oil and grease limitations only for the <br />exempted timeframe. The Division allows these exemptions for a <br />period of to 48 hours after measurable rainfall has stopped. <br />For snowmelt, the Division allows these exemptions for a period <br />up to 48 hours after inflow to the sedimentation pond has ceased. <br />b) Post-Mining Areas - all discharge points: Commencing at the <br />\a`~ time active mining has ceased and surface areas have been <br />~k tt ~ returned to the required contour, and the permit has been <br />R,~ modified, all applicable discharges shall be subject to <br />~y'" limitations other than those specified in Part I.A.1. These <br />~S post-mining limitations shall remain in effect until bond <br />release. The permittee shall notify the Division upon cessation <br />of active mining so that appropriate permit modifications can be <br />made. <br />3. Regulations for Effluent Limitations: The Regulations for Effluent <br />Limitations (10.1.0), apply to the conventional pollutants. For <br />this facility the limitation for Oil and Grease is based on this <br />regulation. <br /> <br />