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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division <br />Rationale -Page 10, Permit No. CO-0043648 <br />V/. TERMS AND COND/TIONS OF PERMIT <br />A. Determination of Effluent Limitations <br />1. E,jjluent Limitations - 7lte following limits will apply and are discussed in Sections Vl.-A.2. and VI.-A.3. <br />a. "No Drscharee"Limitation <br />Except as allowed under the exemptions described in sections VI.A.I.b. and c., the G}esson Mine <br />cyanide heap leach operation, including all ancillary facilities located within the boundaries of the <br />project area, may not result in a point source discharge of process water or combined process <br />water/stormwater to surface waters of the State. /n addition to any immediate notificatiotu required <br />under the exemptions listed below ar the spill provisions of the permit, and the submittal of monthly <br />discharge monitoring reports (DMR'sJ, the perrtittee shall submit an annual report each year, as <br />described in detail in section V/. C.2. of this rationale, and must demonstrate in that rtport that no <br />discharge of process water has occurred. Such demonstration may incorporate the analysis of flows, <br />pollutant concentrations or pollutant loadings. Should the perminee be unable to provide such a <br />demonstration, or the Water Quality Control Division determine that any discharge of process water <br />has or may have occurred, the permit may be reopened in order to modify its terms and conditions so <br />as to further evaluate or to control the discharge. <br />b. Annual Precioitation Exemotion From "No Discharee" Limitation -Discharge Point 007A <br />/n the event that the annual precipitation falling on the Valley Leach Facility and the drainage area <br />contributing surface runoff to the leaching facility exceeds the annual evaporation, a volume of water <br />equal to the difference between annual precipitation falling on the facility and the drainage area <br />contributing surface runoff to the facility and annual evaporation may be discharged subject to the <br />limitations set forsh in Table VI-1. Verbs[ notification shall be given within 24 hours, and written <br />notification shall be submitted to the Division within 5 days of the discovery of any discharge from the <br />Valley Leach Facility that may qua[fv far this exemption. <br />c. Storm Exemption From "No Discharee" Limitation -Discharge Point 007A !f any discharge from the <br />Valley Leach Facility occurs as a result of the 10-year, 24-hour storm volume being exceeded, that <br />discharge will be subject to the limitations set jonh in Table VI-1, unless, for water quality standard <br />bused limits, the permittee demonstrates that instream pollutant concentrations did not exceed the <br />corresponding stream standards. Verbal notification shall be given to the Division within 24 hours of <br />the discovery of any discharge from the Valley Leach Facility that may qualify for this exemption. <br />Additionally, if the permittee intends to use the l0-year, 24-hour storm exemption from technology <br />bused effluent limitations provided in 40 CFR Pan 440, Subpnn L, n report must be submined within <br />90 r/mtc n(ter the effective date ojthis permit, documenting that the facility is designed, constructed <br />and will be maintained to contain: <br />aJ 77~e maximum volume of wastewater which would be generated by the facility during u 24-hour <br />period without an increase in volume from precipitation; and <br />6J The maximum volume of wastewater resulting from a IO-year, 24-hour precipitation event, <br />including the volume which would result from all areas contributing runoff to the "zero discharge" <br />area or process (i. e. , all runoff not diverted from the area or process subject to the Zero <br />dischnrgeJ. <br />