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<br />COLORADO DEPARTMENT OF HEALTH <br />Water Quality Control Division <br />Summary of Rationale Page 2 <br />Permit Numbe r. CO-00001244 <br />FACILITY DESCRIPTION: ;continued) <br />An are sorter is present and uses water from [he <br />retention ponds. However, the water used in the ore <br />sorter is in a closed system and does not return to <br />the retention ponds. <br />Waste rock from the ore sorter is platted in a dump <br />upstream, adjacent [o Ralston Creek, northwest of the <br />mine site. Runoff from this dump is c.urrenily <br />uncontrolled and may reach Ralston Creek. Diversion of <br />water above the waste dump and a collection structure, <br />such as a berm, below the dump are needed. In order <br />to remedy this situation and achieve compliance, a <br />Best Management Practices Program will be required as <br />outlined on page 15 of this permit. This program will <br />specifically address control of surface runoff from <br />the entire facility including the waste rock dump. The <br />report will be due 180 days after this permit becomes <br />erfective. <br />The ore stockpile located southeast of the facility <br />has a small berm that will contain any runoff associated <br />with the piles. This dump will not need to be adgressed <br />in the BMP report. <br />The past permit was in part, written to address effluent <br />discharged from the domestic wastewater treatment <br />facility. Since that time, a septic tank and leach field <br />have now been installed. This permit will not include <br />limitations, such as BOD and fecal coliform, directed <br />to the discharge of domestic waste. <br />Il. EFFLUEIJT LIttITATI0N5 AND RAT4CNALE: <br />Based on testimony by Cotter Corporation before the <br />lJater Quality Control Cammission during [he South <br />Plate River stream Classificaticn Hearings and <br />concurrance by the division, the value for the <br />7 day - 10 ;•ear low flow event is zero. The Water <br />Quality Contrcl Division concurs with [his value due <br />to a lack of data [o refute the zero value. Because <br />the Q7_10 is zero, mcst water euality limitations are <br />based on water quality standards or Best Engineering <br />Judgement of Best Available Technology. <br />An analysis of self monitoring reports submitted by <br />the permittee `tom January 1979 throug~ Hatch 1981 <br />under [he previous permit, was performed. The following <br />table summarizes the results. <br /> <br />