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Mr. Richard Atkinson May 20, 1981 Page Two enclosed copy of 6 sheets of computations contains the following information: Sheet 2 - Lomtion of the revised ditch Sheet 3 -Additional area to be reclaimed Sheet 4 - Data for ditch sections where ditch is diverted away from fill along shape of Mount Streeter and into a natural draw Sheet 5 - Ditch sections for the above described reach Sheet b - Hydraulic of the sections for the above described reach. Streeter Gulch Sedimentation Pond -- As noted under the findings for Streeter Gu c Ditch the area to ere aimed within the Streeter Gulch drainage area increases by 74 acres. This has a significant effect only on the amount of area disturbed or under reclamation during the period 1981 - 1986 as all of this additional area should be fully reclaimed by 1986. With this information the Streeter Gulch information given on page 3 of our May 14, 1981 letter, subject: Colowyo Permit Application, Colorado Mined Land, Reclamation File No. C-019-81 is revised as follows: Area (ayes) Areas Distur ed Undistru ed Distur e n istur e and and under 1 or and under or Years reclamation () fully reclaimed reclamation fully reclaimed Streeter Gulch (1367a) 1981 -1986 213 1986 -1991 181 1991 -1996 112 1996 -1999 41 1154 15.6 84.4 1186 13.2 86.8 1255 8.2 91.8 1326 3.0 97.0 Av = 0 0 Av = 90.0 (1) Assuming 5 years from first distrubance of an area until area Fully reclaimed Using the average disturbed area percentage of 10.0% the weight CS value for the USLE equation becomes: Streeter Gulch, CS =0.092 x 10.0% + 0.013 x 90% = 0.021 With this C factor the 3-year sediment yield computes to be 1 .74 aQe feet, a very modest increase over the 1.66 aQe feet for the previous fill configuration, and within the provided 1.85 acre feet with the existing facilities. Therefore, no change in the Streeter Gulch Sedimentation Pond is needed on account of the revised fill configuration.