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<br /> <br />iii iiiiuiiiiiuiii <br />9 <br />September, 1997 <br />Mr. Dan Mathews <br />Environmental Protection Specialist <br />Colorado Division of Minerals and Geology <br />1313 Sherman, Room 215 <br />Denver, CO 80203 <br />Subject: Blue Mountain Energy, Deserado Mine <br />C-81-018 <br />Technical Revision No. 42, Merger of Refuse Piles 2, 3, & 4 <br />Deaz Mr. Mathews: <br />Blue Mountain Energy has revised submittal materials in response to your preliminary adequacy <br />letter for Technical Revision (T.R.) 42 dated October 15, 1996. The original maps have been <br />certified, and a nttmber of modifications have been made. Responses to the adequacy letter follow. <br />1. The final elevation of the merged refuse pile will be 5620', and will be crowned at a grade <br />of 2% towazds the east and west. Map 150 has been modified to show the crest and its <br />elevation and slope specifications. <br />2. Please replace the SEDCAD+ modeling in Illustration 44 for Ponds RP-2-3 and RP-4. <br />These revised nuns utilize a curve number of 94 to portray a worst case runoff situation and <br />CPs of 1.00 to represent the worst case, baze slope. <br />3. Blue Mountain Energy pumps these ponds as soon as practicable after a storm event, and <br />uses the runoff for dust suppression. As a consequence, the trickle tube was utilized as a <br />modelling artifice to reflect the use of the storage volume between the principal spillway <br />elevation and the sediment storage volume. A note to that effect has been placed on the Pond <br />Input-Output Table of both SEDCAD+ runs. <br />4. The riser information is correct; the elbow between the riser and the barrel is below the <br />bottom of the pond. Previous maintenance activities have stayed away from the outlet works <br />to prevent damage. <br />Certifications have been provided for all maps included in the submittal. <br />6. The Pit 4 West Ditch and the Pit 5 East Ditch Dozer crossings aze now shown on Map 150. <br />7. Map 76 includes information on the combined sub-azeas 2-3 and 4. <br />Map 150 has been modified to show the intersection of Ditch Segment 7 for Pond RP-4 and <br />Ditch Segment 8 for Pond RP-2/3, to eliminate the possibility that disturbed azea runoff <br />would leave the site before passing through a sediment pond. <br />