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Exhibit 19(20) <br />Drill Sites located where <br />run -off does not report to a sediment pond <br />Small Area Exemptions <br />Silt Fence Design for Drill Sites <br />Notes for Calculations: <br />1. Exploration holes are periodically drilled within the permit boundary but outside <br />the area where run -off is contained in a sediment pond. <br />2. The 3 inch 10 -year 24 hour event was used for the silt fence designs. <br />3. The drainage area of a typical drill site is less than one quarter (0.25) acres. <br />4. One half (0.5) acre was used for silt fence design to account for run on from up- <br />gradient areas. <br />5. The up- gradient drainage areas are typically heavy oak shrub, Pinion juniper or <br />Ponderosa pine which all have low run -off potential. <br />6. The following SEDCAD calculations show that during drilling, a 20 foot long silt <br />fence needs placed down gradient of the drilling activities as shown on Map 25. <br />7. The following SEDCAD calculations show that after reclamation a 30 foot long <br />silt fence needs placed down gradient of the reclaimed drill site as shown on <br />Map 25. <br />8. Silt fences will be used to treat run -off from exploration holes drilled along the rail <br />corridor similar to what is shown on Map 25. The rail corridor is considered an <br />industrial area. Once the rail corridor drill site is re- graded, no ongoing <br />sedimentation control is required. <br />ENGINEER'S CERTIFICATION <br />The calculations and information presented on pages EXH. 19(20) -2 through 19(20) -17 <br />with a date of 01/25/12 were yo by me during the month of January 2012, and the <br />information presented issB p to the best of my knowledge and belief. <br />��vira <br />E Stover 3 qi Date <br />Register <br />State <br />MR -107 Page EXH. 19(20) -1 01/25/12 <br />