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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division <br />Rationale -Page 9, Permit No. CO-0043d48 <br />2. Quantity. Acute and Chronic Low Flows -The flows which will be used to calculate acute and chronic <br />effluent limitations are the one day in three year Jow flow (IE3J and the 30 day in three year !ow flow <br />(30E3J respectively. Those flows have been determined for Arequa Gulch by the Water Quality Control <br />Division, and are as follows (all flaws in cubic feet per second): <br />Table HI - 3 - Atute and Chrome Low Flows <br />Acrite ; Chronic <br />Annual 0.0 0.0 <br />3. /mnacts on Downstream Water Supplies or Other Receivinx Waters: The facilities associated with the <br />Cresson Project were designed with the imention to prevent any point source discharge of process water to <br />surface waters. This permit will provide a means to monitor the project in order to detect whether or not <br />such drscharges are occurring and to provide a means to control them If such discharges are avoided, it <br />is possible that there will be no significant impact to downstream stream segments or water users. <br />lV. FAC/LITYDESCRIPTION <br />A. /ndustry Description <br />/. Tvoe of /ndustrv -This facility is a cyanide heap leach gold mining operation. The project will entail the <br />movement of existing mine tailings, the construction of a leach pad (2 phases), construction of overburden and <br />waste rock storage areas, ore extraction and crushing, and cyanide leaching and gold recovery processes. <br />The ore production rate is planned to be 8 million tons per year, with a projected mine excavation period of <br />seven years. The leaching facility will be operated for approximately nine years. <br />Reclamation of the mine site will include backfilling mine pit areas, detoxification of the cyanide leach heap, <br />breaching the leach pad liner system, and revegetation of disturbed areas. <br />2. Potential Sources of Pollutants -This project has been designed with the intention to atroid any discharge that <br />would ordinarily require a permit. However, there is the possibility that unplanned discharges may occur as a <br />result of the new mining activity, or already exist as a result ojhistoric mining activities. The sources of the <br />pollutants that may be discharged include cyanide or metals that may be seeping through existing mine tailings <br />or may be released after the movement of the tailing, spills or leaks of cyanide leaching solution from the new <br />leach heap, or metnlc released from rock that will be exposed to the environment as a result ojthe mining <br />activity. <br />3. Chemicals Used -Other than the pollutants discussed above, no other chemicals which may be stored at the <br />mine site are likely to be present in quantities or used in a manner which would pose a risk of being <br />discharged to wnteec of the S[nte. <br />B. Wastewater Treatment Description: Since no discharges are planned, no treatment ryrtem has been incorporated <br />into the mining plnn,c. <br />V. PERFORMANCE HISTORY -Reserved <br />