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% <br /> } 1746 Cole Blvd, Suite 130 <br /> Lakewood, CO 80401 <br /> P: 303.5REc.32-5a0.1 iVED <br /> Technical Memorandum NOV 0 E 2018 <br /> Divi;:ion of ReclamatiOtl, <br /> To: Chuck Zaruba Mining&Safety, <br /> kOO LIc"""11�IoIIS/!8 <br /> FROM: Adrien Butler, PE �o ..•••••..•2s <br /> REVIEWED BY: Pete Kowalewski, PE � oo\�N • e�T�Fpr�I, <br /> DATE: 15 October 20181 r 44862 ": <br /> PROJECT NAME: Upper Pit 6900 Access Road 0,j,.5) • �/ <br /> PROJECT NO.: 363 k, FS' ••••• <br /> ,t\, /ON .�N� <br /> SUBJECT: Design Summary <br /> cc: Jon Edeen, Jiny Carrera, Pete Kowalewski, David Steed <br /> ATTACHMENTS: A: Construction Drawings <br /> B: Geotechnical Laboratory Test Results <br /> C: Slope Stability Output <br /> D: Drainage Basins and Soils Maps <br /> E: SEDCAD Model Output <br /> Tierra Group International, Ltd. (Tierra Group) was retained by American Gypsum to provide <br /> engineering design and permitting support at the Eagle-Gypsum Mine in Eagle County, Colorado. <br /> American Gypsum currently mines the Upper Pit; the existing road to access the Upper Pit <br /> terminates at the active pit floor at an elevation of approximately 7070 feet above mean sea level <br /> (amsl). The estimated ultimate pit floor elevation is 6900 feet amsl, requiring a modification to the <br /> existing road to reach the lower portions of the Upper Pit. Based on current mining rates and <br /> Upper Pit configuration, American Gypsum will need to begin constructing a new access road to <br /> the lower sections of the Upper Pit within the next 2 months. <br /> This road modification can be considered a minor modification to the original permit M-1984-041. <br /> 1.0 Proposed Road Summary <br /> The Upper Pit 6900 Access Road will tie into the existing road near an elevation of 6970 feet amsl, <br /> extending southeast to the anticipated edge of the Upper Pit at an elevation of 6900 feet amsl. <br /> The road will be constructed primarily in fill, utilizing non-economic, inert material generated from <br /> Upper Pit excavations ("intraburden"). The road will require approximately 257,000 cubic yards <br /> (cy) of fill and 6,500 cy of cut. The road will be approximately 950 feet long, 50 feet wide(including <br /> safety berms), with 1.5H:1V (Horizontal:Vertical) cut and fill slopes. The maximum (highest) cut <br /> slope will be approximately 25 feet and the maximum fill slope will be approximately 170 feet high <br /> (measured from the road crest to the fill slope toe). Road construction is anticipated to be <br />