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Mr. Gregg Squire • 2 • April 23, 1987 <br />~ Colo. Mined Land Reclamation Div. <br />Construction procedures, as outlined in permit sections 3.7.2 (Haul Roads) and <br />3.7.3 (Access Roads), will be followed. Culvert sizing calculation procedures <br />are presented in Section 4.8.1.2 of Trapper's permit revision, PR-2. Table <br />4.8-1 of PR-2 shows the culvert sizing information needed for the haul/walk <br />road. Not shown is culvert A-2A, which will drain [he discharge from Impound- <br />ment H (NPDES Point 4k007). Culvert sizing calculations for A-2A indicate that <br />a 24-inch culvert based on a peak discharge of 0.51 CFS will be installed. In <br />addition, culvert sizing for A-2 was reduced to one 60-inch culvert vice the <br />two 40-inch culverts as shown in Table 4.8-1. <br />Culverts, if needed for the access roads to north Ashmore Pit, will be 24 <br />inches in diameter. They will be placed as needed to maintain control of road <br />water runoff and uninterrupted flow of runoff from drainageways. <br />The development of the road system will also affect slightly the diversion <br />ditch plan as shown on Permit Map M51. The diversions, Johnson Gulch No. 1 <br />and No. 2, which route runoff .from nondisturbed areas around Johnson Gulch <br />sediment pond No. 10, will be removed. Additionally, the small area exemption <br />5 will no longer be required as the runoff from the substations will be routed <br />into the Johnson Gulch sediment control system. These changes have no signi- <br />ficant impact on the Johnson Gulch sediment control systems. <br />Tables 1 through 4 show the bond calculations for the additional disturbances <br />from the construction of the proposed road system. Costs are based on rates <br />and production estimates outlined in PR-1. The revised bond calculations show <br />an increase of $140,616.75 for 1987. <br />Gregg, following approval of the technical revision, we will revise appro- <br />priate sections of PR-1 and PR-2, such that they are consistent with this <br />technical revision. Specifically, a revised map M51 will be submitted for <br />PR-1 and PR-2 concerning the removal of Johnson Gulch diversions No. 1 and No. <br />2. Permit section 4.8.6 will also be rewritten to reflect removal of small <br />area exemption No. 5. Anew roads map, M9, will be submitted for PR-2 showing <br />the road locations and appropriate culvert locations. Finally, a revised <br />permit table, 4.8-1 for PR-2 will be submitted showing culvert A-2A and the <br />change to culvert A-2. The attached maps M9 and M10H revises those submitted <br />with PR-1. <br />Please contact me if you have any questions or require additional <br />information. <br />Sincerely, <br />J~/.iL.~ZJ~~ <br />H.B. Humphries <br />Sr. Environmental Engineer <br />LWH/mg/jb <br />Enclosure <br />pc R.L. Fanyo <br />L.W. Henderson <br />J.M. Mattern <br />file <br />