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structure was designed using the pond routine in SedCAD 4 to handle the peak discharge from a 10-year, <br />24-hour storm event. Length of the silt fence and straw bales was determined from the topography of the <br />site and from the necessary sediment storage to comply with the allowable settable solids limit. Input <br />discharge rates for the SedCAD model were calculated from a permissivity rate of 5.6 gpm/ft2 for straw <br />bales and a rate of 10.0 gpm/ft2 for a silt fence. SedCAD demonstrations and a typical design drawing for <br />a silt fence and a straw bale implementation are provided in the TR-60 Exhibit text. <br />Comment 6. Please refer to Comment 7 of the Adequacy Review for details. <br />Comment 7. SedCAD designs are provided for the Pad, Topsoil, and Laydown SAEs. Silt <br />fences or straw bales placed along the contours of the SAES will be used to control sediment. SedCAD <br />runs for the three SAEs show that concentration levels coming out of the straw bales or silt fences are at <br />or below the settable solids limit of 0.5 ml/1. The sediment control structure was designed using the pond <br />routine in SedCAD 4 to handle the peak discharge from a 10-year, 24-hour storm event. Length of the silt <br />fence and straw bales was determined from the topography of the site and from the necessary sediment <br />storage to comply with the allowable settable solids limit. Input discharge rates for the SedCAD model <br />were calculated from a permissivity rate of 5.6 gpm/ft2 for straw bales and a rate of 10.0 gpm/ftz for a silt <br />fence. A SedCAD design for a typical silt fence and a straw bale implementationare provided in the <br />Exhibit text. <br />Comment 8. Revised SedCAD runs indicate the length, height, and tie back distance of the <br />straw bale or silt fences. All of the SAES were designed with a flow rate corresponding to straw bales. <br />Also, the pad area will be covered with a layer of gravel to help slow down the flows and control <br />sediment. A cover of straw, mulch or erosion control mats plus seeding will be employed on the Topsoil <br />SAE to slow down flows and help control sediment. <br />Comment 9. The Drawing 2.05-El-BCA2 has been modified to include labeling of the three <br />SAE's. <br />Comment 10. Entry Road - The Bear Creek ranch road will simply turn into the fansite and or <br />light use road and no culvert is needed. Further, the fansite light use road is proposed to improve access to <br />the backside of the pad. <br />Comment 11. A light use road/access ramp was added to access the laydown area. Where this <br />light use road crosses the drainage the side slopes of the small drainage will be laid back to create access. <br />Comment 12. The area shown in the post mine topography covers the proposed laydown area <br />as shown on Drawing 2.05-E1-BCA2 <br />Comment 13. Time of concentration values for BCC-1, BCCD-1 and BCCD-2 were <br />reevaluated and adjusted in the SedCAD designs based on the established watershed boundaries. <br />Comment 14. The area of the laydown SAE was adjusted and is shown on Drawing 2.05-E1- <br />BCA2 and the watershed from above the laydown area was added. The input areas of the watershed above <br />the laydown area and the laydown area are 0.5 acres and 0.2 acres respectively. The summary sheet was <br />revised according to the new laydown area. <br />Comment 15. A permissivity value of 5.6 gpm/fC was used to model straw bales in the <br />SedCAD designs for the three SAEs identified in Drawing 2.05-E1-BCA2. A permissivity value of 10 <br />gpm/ft was retained from the original TR-60 to model silt fences for the three SAEs. <br />Comment 16. Please see reference to Map 2.05-E1-BCA2 on the attached revised page 2.05-37. <br />• Page 2