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1 <br /> <br />1 <br />1 <br /> <br />Water leaving the mine as ventilation humidity represents a large quantity in the water balance. The <br />temperature of the exhaust ventilation air is almost constant, ranging from 60° in winter months to <br />63°F in summer months. The relative humidity of this air ranges from 80% in the summer to 95°~ <br />in January and February. Throughout the year, except for the months of June, July and August, the <br />ventilation air is warmed as it passes through the mine. This increases its moisture carrying capacity <br />and the air picks up considerable quantities of moisture wherever there is water available. During <br />the summer months the air is actually cooled, however, the difference in relative humidity still allows <br />the exhaust air to carry away more moisture than is brought in with the intake air. <br />' Some of the water entering the mine is collected in sumps at various locations. In the past, this <br />water was eventually pumped out of the mine through the East Intake or to process pond two (PP2). <br />All water discharged from the mine is now discharged at the sump dewatering holes shown on Plate <br />' 1. During this year approximately 83% of the total was discharged from SDH-2 and 179'° from <br />SDH-3. This water is further discussed in the next section. <br />2.2.2.6 NPDES Discharges and Whole Effluent Testing At present, Western Fuels-Utah has 13 <br />NPDES ouffalls. One additional ouffall has been applied for for the new refuse disposal area pond <br />(RP-5). Seven of these ouffalls have never experienced a discharge and an eighth has had one <br />discharge since construction 12 years ago. The vast majority of water is discharged from the ouffalls <br />for the mine dewatering boreholes (SDH-1, SDH-2, SDH-3 and SDH-5). The water from SDH-1 <br />' and SDH-2 is discharged at ouffall 024 and the water from SDH-3 and SDH-5 is discharged at <br />ouffall 026. The NPDES discharge quality parameters for the water year are summarized in Table <br />' 2-4. There was one exceedance this year of oil and grease from ouffall 026. This was due to a <br />vehicle accident underground and the application of a floculent to the pond reduced the subsequent <br />discharged oil and grease to within the permit requirements. <br />' Western Fuels-Utah started the whole effluent toxicity (WET) testing program beginning in the fourth <br />' quarter of 1989. The mine water effluent was found to be toxic to the test species. Accelerated <br />testing was conducted but the toxicity to the species continued. <br />' In a meeting with Colorado Water Quality Control Division (WQCD) staff on January 31, 1992, the <br />WFU staff reiterated the biomonitoring events, and various measures taken to identify the toxicants <br />and to reduce the toxicity. WFU has taken the following steps to identify potential toxicants. <br />' • In the eady stages of WET testing, the undisassociated HZS in the effluent was <br />' deemed to be a potential toxicant. However, a WET testing done by ENSR <br />Consulting in June 1990 after removing HZS by aeration still showed toxicity. This <br />result indicated that some other factor(s) also contributed to the toxicity. <br />' 13 <br /> <br />