Laserfiche WebLink
• <br />ATTACHMENT 1 <br />Hydrology Response to Adequacy Concerns <br />1. Peerless revised their mine facilities area including the Mine <br />Facilities Map (Map 12). The Road Design Map (Map 13) must be <br />revised to reflect the road changes shown on Map 12. <br />Response: The Mine Facilities Map (Map 12) has been revised to <br />reflect recent exploration activities as surveyed in mid-May, 1985. <br />The Road Design Map (Map 13) has been updated to correspond to this <br />latest revision. Both of the updated and revised maps are enclosed <br />for substitution in the permit application document. <br />2. Culvert C-2 has been designed to convey flows with 5.4 feet of head <br />(my calculations show 5.8 feet). This is too high and the culvert <br />must be re-designed to convey flows with less than 3 feet of head. <br />• Response: The design flow for Culvert C-2 is 28.8 cfs. From the <br />Standard Culvert Sizing Nomograph, assuming a projecting inlet, <br />Culvert C-2 has been resized as a 36 inch diameter CMP with 2.85 <br />feet of head. <br />3. The following comments apply to Ditch No. 1: <br />a. The aooarent aaproach for selection of the curve number needs <br />to be clarified. It appears that Archuleta-Sanchez Complex <br />soil type was utilized to typify the entire drainage basin, <br />yet this soil type is confined mostly to the valley bottoms. <br />In addition, weighted averages should have been used for <br />different vegetative types and covers to develop a curve <br />number which more closely details actual site conditions. <br />Response: Due to incomplete listing of soil groups, a conservative <br />group of D has been selected. Therefore, a weighted average method <br />• to develop the average curve number does not increase the accuracy <br />of the estimate. The assumed curve number of group D soils and <br />-1- <br />