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'il.1 <br />i <br />TETRA TECH <br />January 12, 2010 <br />Mr. Jared Ebert <br />Environmental Protection Specialist <br />Division of Reclamation, Mining and Safety <br />Department of Natural Resources <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br /> <br />WF111 W <br />SAN 12 2010 <br />Division ui INOLA T11W! <br />Xv Wning and safety <br />RE: Response to Adequacy Review #3 Comments for Lafarge West, Inc's Greeley <br />35th Avenue Mine, DRMS File # M-1977-036, Amendment 01 <br />I'll ;17 <br />Dear Jared: <br />This letter is in response to your Adequacy Review #3 Comments for Lafarge West, Inc's <br />Greeley 35th Avenue Mine, DRMS File # M-1977-036, Amendment 01. Below is a <br />listing of the comments followed by our responses to those comments. <br />6.4.6 EXHIBIT F - Reclamation Plan Map <br />1. Page E-2 of the reclamation plan indicates slopes above the post mine water level will <br />be reclaimed to a 4H:1 V (horizontal to vertical) ratio and slopes below the post mine <br />water level will not exceed a 3H:1 V ratio. Given this commitment, there are several <br />discrepencies on the Reclamation Plan Map. For the West Pit and the two South <br />Central Ponds, the majority of the pit slopes are depicted with 3H:1 V reclaimed <br />slopes from the bottom of the pit to the top of the pit above the post mine water level. <br />The southern pit slopes of the North Central Pit and the eastern pit slopes of the <br />Mining Cell are depicted to have 2.5H:1 V reclaimed slopes above the post mine <br />water level. Also, page 3 of the Reclamation Plan Map indicates the typical pond <br />slopes will be reclaimed to a 3H:1 V ration for the entire length of the slope. Please <br />revise the maps to correspond to the proposed reclamation plan or revise the <br />reclamation plan to leave 3H:1 V slopes above the post mine water level. In either <br />case, the slopes depicted for the southern slopes of the North Central Pit and the <br />eastern slopes of the Eastern Mining Cell will need to be re-drawn to correspond to <br />the proposed reclamation plan. <br />We have corrected page E-2 of Exhibit E: Reclamation Plan to indicate that slopes <br />both above and below the post-mine high water level will all be 3H:1 V or flatter. In <br />addition, we have modified the Exhibit F.• Reclamation Plan Map to make sure all <br />slopes are shown at 3H.•1 V or flatter. <br />1900 S. Sunset Street, Suite I-F Longmont, CO 80501 <br />Tel 303.772.5282 Fax 303.772.7039 www.tetratech.com