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condition and a HSG B for the above- captioned land types, gives the following CN values. G-R, good, CN = 61 B-W-G, good, CN = 48 Averaging these values gives a CN = 55. Once again, Colowyo chose to be conservative, and arbitrarily derated both land type range conditions from good to fair which gives, G-R, fair, CN = 69 B-W-G, fair, CN = 56 Averaging these values gives a CN = 63 which is the value used in the model for fully reclaimed, grassland or range, brush weed, grass mix. Please note that all CNs refer to AMC II when in actuality these CNs should be derated by approximately 3o to reflect AMC I found at Colowyo. Therefore, a CN = 63 is very, ver conservative for the site specific characteristics found at Colowyo. Closing Remarks ._ 1. It is important to realize that Colowyo's use of a CN = 63 is conservative due to an arbitrary derating of the land conditions which does not reflect actual conditions found and documented in the field. 2. The CNs found in SEDCAD or from Soil Conservation Service sources, are for AMC II. Colowyo should convert all CNs from AMC II to AMC I to accurately reflect mine site characteristics. This conversion results in a further reduction (approximately 30~) of the CN. 3. Runoff equals precipitation minus losses. Losses documented at Colowyo are evapotranspiration (which is a substantial loss and basis for AMC I), surface storage (difficult to quantify but a valid factor to recognize), and increased infiltration rate (basis for HSG classification). 4. Actual field observations show that sediment ponds constructed at Colowyo continually display minor water levels and inflow. 5. Colowyo has been repeatedly recognized by the Colorado Mining Association and Coal Mined Land Reclamation Division "for an outstanding compliance record and continued exemplary • reclamation performance". a_: