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1992, 1993, 1994 AHR Review Bear Coal Company March 30, 1995 Page 4 calculations in the permit which shows during low flow that there is not adequate flow to flush the contaminants through the alluvium. Although, AA3 is showing some degradation, I do not believe it is impacting the North Fork due to the high flows of the river and the low flows of the alluvium. The following equation is the downstream concentration of TDS in the North Fork after mixing has occurred. Ca = 95 mg/1(21 cfs) + 2800 mg/1(0.091 cfs) 21 cfs + 0.091 cfs Ca = 1995 ma/1 + 254.8 mg/1 21.091 Cd = 106.67 mg/1 TDS ^ 95 mg/1 is the concentration of TDS in the North Fork (from the North Fork CHIA) ^ 21 cfs is the low flow of the North Fork (from BCC permit) ^ 2800 mg/1 is the highest concentration of TDS recorded for AA3 (from BCC AHR) ^ 0.091 cfs is the total flow in the alluvium subject to contamination (from BCC permit) The 1992 AHR report states, "although ground water test data is elevated over the previous year, it appears it was not due to conditions associated with the mining operations at the Bear #3 Mine". This statement contradicts a letter BCC sent to the Division in 1990 regarding the possible cause of the degradation, which noted Bear's operation as the probable cause, and information contained in the permit on page 2.05- 55b. Therefore, this statement referenced should be revised in the 1992 permit. The 1992, 1993, and 1994 AHRs show that 18.5 acre-feet, 17.7 acre-feet, and 12.045 acre-feet of water, respectively, were consumed. The permit projects that the maximum amount of water that would be consumed, based on a 500,000 ton/year operation, would be 19.5 acre-feet. A Windy Gap depletion estimate of 20.6 acre-feet/year was determined during the review of Permit Revision No. 1 (1993/94). Report Content Requirements