Laserfiche WebLink
• Return Period/Precipitation <br />_ • Hydrograph Response Shape <br />• • Drainage Basin Area <br />• Time of Concentration <br />• Curve Number <br />C, <br />J <br />• <br />Preci~ation Distribution <br />A precipitation distribution is input to model the runoff hydrograph. SEDCAD+ allows [he <br />user to choose between the SCS Type I and Type II storms. For [he Raton Creek Mine Area <br />the SCS Type II Storm is input. <br />Storm Duration <br />A storm duration of 24 hours is used for design of structures at the Raton Creek Mine. <br />Return Period/Precipitation <br />A precipitation amount is required for the appropriate return period. The following <br />precipitation values are used: <br />Drainage Structure Section Return Period Precipi[ation (in) <br />Watershed Diversion MI A, B I00-yr, 24hr 4.6~ <br /> C 3.2) <br />Wuershed Diversion M2 A, B ~ CIO-yr, 34hr <br />~ ~ 4.6 <br /> C 3.2 <br />Watershed Diversion N3 A, B -16o yr, 24hr 3.2 <br /> <br />Watershed Diversion K4 A, 8 10-yr, 24hr 3.2 <br />Refine Sediment Collection Ditch No. 1• A, B, C 100-yr, 24hr 4.6 <br />Refuse Sediment Collection Ditch No. 2 All I00-yr, 24hr 4.6 <br />Yard Ditch 2 A 10-yr, 24hr 3.2 <br />*The mine bench area (7.6 acres) diverted to Refuse Sediment Collection Ditch No. 1 <br />contribu[es runoff generated from the 1C-year, 24hour storm. This value is added to the runoff <br />calculated for 100-yeaz, 24-hour storm. <br />Precipitation values were obtained from the "NOAA Atlas 2, Precipitation Frequency Atlas of <br />the Western United Stales, Volume 3, Colorado." <br />C:\mORA~H56ATR09.REV 358Rd Revised - Ma 1993 <br />OS/iN9) Spm }~ <br />