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i1 HYDROLOGIC ASSUMPTIONS FOR THE RUNOFF PONDS <br />• In order to perform the major basin hydrologic analysis for the runoff ponds, two <br />assumptions were made: <br />1. The ditches used in the minor (10 year) system are assumed to have no <br />affect on the inflow design flood. These ditches are sized for fer smaller <br />flows and in most cases, these ditches are within the tributary basin to the <br />ponds. The major drainage basins were delineated following natural drainage <br />patterns without regard to ditches. <br />2. The road, in areas of cut, is assumed to have no affect on drainage patterns. <br />In areas of fill, the flow will follow the road grades. This was based on the <br />fact that most of the road will be in a side hill cut and this geometry will <br />have a minimal impact on the drainage. Areas of fill are located primarily <br />on curves and in areas where the ground is reasonably level. <br />The hydrologic analysis for the inflow design flood was performed following the <br />procedure outlined in "Design of Small Dams"; U.S. Department of Interior, Bureau of <br />• Reclamation. <br />MISCELLANEOUS SEDIMENT CONTROL FACILITIES <br />The area around the wastewater treatment plant has been treated independently of <br />the other surface facilities. The wastewater treatment plant is located too low on the <br />site to enable storm flows in this area to be ditched or piped to MBn3 and was thus <br />designed with a separate sediment control pond. <br />This facility was sized for the 10 year, 24 hour storm event and 0.1 acre feet of <br />developed sediment per acre of disturbed area. The facility is shown on Page 7 of the <br />Plan Set. Overflow from this facility will flow directly to the North Fork of the Gunnison <br />River. <br />GENERAL REQUIREMENTS FOR SEDIMENTATION CONTROL FACILITIES <br />All storm drainage/sediment control ponds have been designed in accordance with <br />the requirements of Part 817 -Permanent Program Performance Standards -Underground <br />• Mining Activities as described in Federal Register, Vol. 44, No. 50 -Tuesday, March 13, <br />1979. In addition, all inspection, construction and maintenance procedures are to conform <br />to the requirements of this publication. <br />