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• TECHNICAL REVISION N0. 14 <br />5. Please address how an existing culvert, 23A, can decrease in size <br />from 24 inches (February 2, 1988) to 18 inches (May 5, 1988) as <br />portrayed on Table 12-3a. <br />Response: <br />The existing culvert, 23A, is, indeed, a 24-inch diameter pipe. Table <br />12-6 (renumbered from Table 12-3a) had an editorial error on the May, <br />1988 submittal. The revised Table 12-6 is attached. <br />6. While reviewing culvert locations on Exhibit 7-7 it appears a <br />culvert is required at the intersection of haul road C3 and the <br />road to the recently approved Dragline Erection Site. If so, <br />please update the permit accordingly. <br />Response: <br />The drainage area proposed at the intersection of haul road C3 and the <br />dragline erection site is approximately 3.6 acres, which is basically <br />the drainage of the side slopes of the C-1 haul road and the southeast <br />side of the dragline erection site. The remaining area of the dragline <br />erection site will be graded to allow runoff to drain to the north and <br />west sides of the site. Assuming a 10-year, 24-hour storm, Curve Number <br />• = 91 and a time of concentration = 0.098 hours, the estimated runoff <br />would be approximately 3 cfs. This is a very minor amount of peak <br />runoff. Based on this peak runoff and a HW/D ratio of 1.0, the culvert <br />diameter would be less than 15 inches. This small of a culvert is not <br />practical due to the potential for silting and the maintenance <br />requirements; therefore, a culvert is not recommended for this <br />intersection. <br />7. The Division would concur that there are some instances associated <br />with haul road ramps that reclamation would need to be delayed <br />beyond 180 days as being proposed on revised page 12-53. However, <br />these ramps need to be actively used and Peabody should inform the <br />Division of such delay to avoid any potential problems. Also, <br />Peabody will have to verify adequacy of the bond amount each time a <br />ramp is proposed to be retained in such a manner. <br />Response: <br />Peabody agrees with the Division. <br />8. It is interesting to note that while this revision application <br />pertains to the addition of the East Wadge Extension Area <br />(prominently displayed on Exhibit 12-2), no real mention is <br />specifically made in this tab. A discussion addressing the new <br />deadhead route, mining to the lease boundary, spoiling east of the <br />• lease boundary, etc., needs to be placed into this tab. <br />Also, specific reference to dimension, grade, etc., of the existing <br />and proposed 770 deadhead route should be incorporated into the <br />discussion on page 12-49. <br />7 <br />