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<br />6. What is the source for the particle size distribution used to model the hydrology and <br />sedimentology of the facilities area? <br />7. Page 4.6-34a of the revised text states that the facilities sediment pond is designed to <br />completely contain the 10 and 25 year-24 hour storm events. The modeling output <br />shows a discharge from the pond for both events. Is one of these statements in error? <br />8. Output tables from the modeling exercise show the permanent pool elevation in the <br />pond is 7808', a volume of 15.66 acre feet. If the primary spillway (siphon tube) is at <br />an elevation of 7808', the volume entering the pond during the 10 year event should <br />equal the volume discharged. This is not the case in the output submitted. Please <br />explain the discrepancy. <br />9. Rule 4.05.6(4) requires a minimum of 1' vertical spacing between the crest of the <br />primary spillway and the crest of the emergency spillway. The information provided <br />shows the crest of both spillways at 7809'. Please revise the design to provide for the <br />required spacing. <br />10. Please provide the Division with detailed drawings of both spillway systems, as required <br />by Rule 4.05.6(7). <br />11. From the drawings provided, we are unable to determine whether there is a minimum <br />of 1' of freeboard available in the emergency spillway when flowing at design depth <br />(Rule 4.05.6(11)(e)). Please provide additional information to demonstrate compliance <br />with this requirement. <br />12. Page 4.6-34a states that the height of berm MP-1 will be approximately 2'. Please <br />provide the Division with specific dimensions of the berm. <br />13. The facilities area ditches were designed with a freeboard allowance of 1 foot. The <br />minimum requirement for freeboard per Rule 4.05.3(7)(b) is .3 feet. <br />14. Facilities ditch FD-1 was designed to be 25' wide and 1.25' deep. We believe that the <br />width and shallowness of this ditch is excessive, and that sheet flow through the ditch <br />would not be likely. To prevent formation of a gully in the center of the ditch, the ditch <br />might better be designed and constructed to be deeper and narrower. <br />15. The model output shows that the velocity of water from the drop structure to the <br />sedimentation pond is 21.23 fps. Velocities in excess of 5 fps are considered to be <br />erosive. Please explain how P&M will control erosion at the inlet. <br />Daw ever m 2 August 1, 1 3 <br />