Laserfiche WebLink
Mr. Lawrence G. White, P.E. -S- October 28, 1994 <br />8. Our runoff prediction assumptions and estimates are as follows for the area proposed to <br />drain to the mine bench sediment pond: <br />CN=73 <br />10-year, 24-hour precipitation - 3.0 inches <br />25-year, 24-hour precipitation - 3.4 inches <br />Drainage Area = 27 acres <br />l0~ear.24-hour 25-year. 24-hour <br />Peak (cfs) 26 33 <br />Volume (ac.ft) 1.95 2.5 <br />These are rough estimates. The total pond volume is apparently 0.88 acre-feet; however, <br />the discharge works may accommodate these flows. <br />Please provide discharge works calculations to verify that the 10-year, 24-hour storm can be <br />treated, and safely passed. Likewise, provide calculations to show that the 25-year, <br />24-hour storm can be safely passed with the combined spillways. <br />Please also check our pond volume number and inflow calculations to ensure that we have <br />portrayed reasonable numbers. <br />9. The cobblestone check structure may actually create problems. If water overtops the <br />structure, more damage could occur than if the water was passed to the pond unobstructed. <br />Please provide any ideas on this matter. <br />10. We will continue to assist in resolving these issues to the extent possible. <br />Coal Sales Area <br />Structural Removal <br />1. The landowner has requested that the following structures be retained at the Coal Sales <br />Area: Office building, well and well house, incoming power, and road. <br />Please provide information to indicate that these facilities will enhance the post-mining land <br />use. <br />2. Please verify that all other structures, foundations, debris, and equipment will be properly <br />disposed. <br />3. Are there any PCB-containing transformers at this site? )f so, how will they be <br />decommissioned? <br />