PERMFILE128415 - Laserfiche WebLink

Home Browse Search

• Exhibit IS -Pond TABLE 9 LORENCITO CANYON MINE SOIL ERODIBILITY FACTORS (In FOR SOIL ASSOCIATIONS Soil Erodibility Factor (or Series Soil Erodibility Factor' Association Shawa 0.24 0.24 Trag 0.20 0.20 Fughes 0.24 0.24 Louvier 0.32 0.32 Sarcillo 0.20 Trag 0.20 Fuera 0.37 0.37 Dargol 0.37 Vamer 0.28 Saruche 0.32 - 0.37 Rombo 0.37 Louviers 0.32 0.37 Rombo 0.37 Travesilla 0.37 Manzano 0.28 0.28 Haverson 0.28 0.28 ' U.S. Natural Resources Conservation Service, 1996 (unpublished). • Z Association soil erodibiliry factors developed by using the highest soil erodibility factors of a series within an association. • Slopes were derived from the average slope found within the watershed during the time of concentration analysis. The waste rock dump tops and dump faces were analyzed as multiple micro- subwatershedswithin the watershed. When the hydraulic length ofa watershed traversed amining- relateddisturbance, the slopes and lengths of the predominant terrain within the watershed was used. Cover practice values were derived from baseline vegetation data collection in reference areas and best professional judgement about conditions in disturbed areas. Assumptions used to derive cover practices and the resulting values maybe reviewed in Table 10. The results for sediment generation from discrete storm events were extrapolated to annual sediment loss for use in the pond calculations. Tons of sediment were divided by the watershed acreage to obtain a sediment yield in tons/acre. The yield was multiplied by the ratio of the annual rainfall value (R) for this area of Colorado of (70) and the annual specific storm rainfall amount to generate annual sediment loss for the watershed. The SEDCAD+ modeling describes sediment loading of the streams associated with discrete storm events. Most erosional and depositional processes occur in conjunction with storm events. 7 (revised 4/20/01)