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Ms. Christine Johnston <br />Mountain Coal Company <br />Page 6 <br />August 23, 1996 <br />22. On page 15 under Sanitary Waste Water, the percentage of sanitary waste <br />water discharge that contributes to the average daily flow of the North Fork <br />Gunnison River is incorrectly calculated (0.07 should be 0.007). Please check <br />this calculation and submit a revised report page. <br />23. On page 17 under Water Quality, it states that samples taken during 1993 <br />indicate water quality in the mine to be good. There is no mine inflow water <br />quality data presented in the report. if these data are available, please <br />provide them on a revised report page. Refer to comment 17 above. <br />24. On page 15 under Mine Water, the numbers provided for total mine water <br />inflow and total water exiting the mine do not match the numbers provided <br />on Table 6, page 9. The total mine water inflow listed in Table 6 is 117.4 <br />acre-feet and the estimated sustained Flow is 5.0 acre-feet (the text on page <br />15 shows 68.2 acre-feet). The total mine water outflow shown on Table 6 is <br />118.9 acre-feet and on page 15 it states that the total water exiting the mine <br />was 74 acre feet. Please clarify what the estimated mine inflow was for WY <br />1993 and provide additional text to substantiate the water balance numbers _ _ <br />provided in Table 6. <br />25. The second paragraph on page 16 states the following. "During spring runoff <br />conditions, as well as during some precipitation events, the quality of water <br />in the North Fork of the Gunnison is much worse than the quality of <br />discharges from MCC sediment ponds." Please clarify this statement. The <br />data provided in this report do not appear to substantiate this claim. <br />26. On page 16 under Runoff from Disturbed Area, there is no discussion for the <br />other ponds that had discharges during WY ]993 (W WTP/007A, MB-5/009A, <br />MB-6/OlOA). For consistency, in future AHRs please provide a brief <br />discussion of all discharge points. No revision to the 1993 AHR is necessary. <br />27. On page 17 under Water Quality, it states that "quality of water discharged <br />in WY 1994 should be similar to the WY 1993 values shown in Table 7". <br />Table 7 shows quality of water runoff adjacent to the refuse pile and contains <br />a value of 121 mg/I for total iron, which is outside of the CDPS discharge <br />limitation for iron. Although water is treated in a sedimentation pond prior <br />to discharge, this is still a high value for iron. Is water runoff from the refuse <br />pile area going to be representative of discharge for WY 1994 across the <br />entire mine site? Please clarify this with additional text and provide a revised <br />report page. <br />