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COLORADO DEPART7NEM OF PUBLIC HEALTH AND ENV/RONMEM, Water Quality Control Division Rationale -Page 3, Permit No. CO-A?~t4T16 FACILITY DESCRIPTION A. Industry Description Tvpe q(Industrv: The facility is a recently opened underground coal mine near Paonia, CO. Coal will be mined, stockpiled and loaded our via truths. the permittee estimates production will be two million tons per year. the projected life of the mine is twenty years. 2. Sources to the Treatment Plant: Surface runoff flows from three drainages to Three sedimentation ponds, from which each separately discharges to Deer Trail Ditch. !n addition, mine drainage is pumped to Pond C, where it may commingle with surface runo,(); far sedimentation then discharges ro the ditch. A domestic wastewater treatmem facility will discharge to the ditch via Pand B at a point in the future. 3. Chemicals Used: The pertniaee did not specify any chemicals for use in waters that may be discharged. On this basis, no chemicals are approved under this permit. Prior to use of arty applicable chemical, the permittee must submit a request for approval which includes the most curreru Material Safety Data Sheet (MSDS) far that chemical. Use of any chemical in waters that may 6e dscharged is not approved under this permit, B. Wastewater Treabnent Description Sedimentation is the principle method of treatment for surface runoff and mine drainage. Mine drainage may be commingled in Pond C with surface runoff. Pond C has a volume of approximately eight times the daily design flow volume expected to be generated by mine drainage. If the pond receives the equivalem volume from a 10-year, 24- hour event on a day when the design flow mine drainage volume alto enters the pond, approximately 0.95 day or 22.7 hours detention time would be provided. When the domestic WWTF is added via permit amendment, this source will commingle with surface runoff in Pond B before discharging through outfall 001. The amendment rationale will describe the domestic wastewater treatment in detail. Discharges of surface runoff from this facility (outfalls 001, 002 and 003) have beers previously authorized under general permit certification COG850039. These three outfalls will remain authorized under the general permit until this individual permit is issued. Ar that time, certification COG850039 will be inactivated to avoid a break in coverage for these outfa!!s. This new permit is being developed at this time to address the permittee's need to discharge mine drainage, which cannot be covered under the general permit. At the permittee's request, the Division had been holding up writing this individual permit until site approval for the domestic WWTF was granted, but the permittee has determined that the need to discharge mine drainage will occur prior to site approval, On this basis, the permittee hat asked that this individual permit be written and issued to allow discharge of the mine drainage. When the site approval for the domestic WWIT•' has been received, the permittee will need to submit a request for a permit amendment to add the domestic WWIT'. Pursuant to the authority of Article 9, title 25, $t'gulations for the Certi cation of Water Treatment Plant and Watewater Treatment Plant Operators this facility may require a certified operator. For further information, the permirtee should contact the Colorado Plant Operators Certification Board at (303) 692-3500. V. PERFORMANCE HISTORY ~A. Monitoring Data 1. Discharge Monitorin,q~portc: No Discharge Monitoring Reports have been submitted under this new permit. However, under the previous general permit certification (COG-850039), the permitree has reported for outfalls 001, 002 and 003 from January 1996 through March 1998. No discharge has been reported for all three outfalls except during the Jirsr calendar quarter of 1998, when the permittee reported discharge for outfall 002. Al! parameters were in compliance with the permit limitations.