2005-06-24_REVISION - M2000016 (13)

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~1FARG E NORTH AMERICA AGGREI-aATES, CONCRETE 7L ASPHALT June 24, 2005 Mr. Gregg Squire Division of Minerals and Geology 1313 Sherman St., Rom 215 Denver, Colorado 80203 RECEIVED JUN ? y ?005 Division of Minerals and Geology RE: Sei~ond Adequacy Review Response, Lafarge West, Inc. Riverbend Operation lllc Permit Amendment Ol, Permit No. M-2000-016 Dear Mr. Squire, Lafarge received the second adequacy review from the Division of Minerals and Geology (Division) for the Riverbe'nd Pit 112c Amendment O1, File Number M•2000-016. The following responses have been prepared toiaddress the Division's concerns. For clarity, each of the Division's comments is quoted in italics and followed by Lafarge's response; "Memo Item" refers to the first adequacy review memo dated February 11, 2005. Rule 6.4.4 EXHIBIT D -Mining Plan In the applicant's adequacy response to Memo Item 4, the applicant stated that the requested details and engineering analyses regarding ditch capacity with respect to dewatering and storm water runoff discharges to the various irrigation company ditches "will be calculated during agreement negotiations "and that "the Ditch Company will determine what is acceptable in the agri~ement. "The applicant also stated, "...impacts jof discharges] to Big Dry Creek will be asscssed during Lupton Bottom agreement negotiations. " In order to approve this amendment allowing discharge to the irrigation company ditches, the Division needs executed agreements with the ditch companies and/or engineering analyses demonstrating each structure can accommodate the increased loading. An engineering analysis of tl{e impacts ofproposed discharges to Big Dry Creek must also be provided. Lafarge has amended the original requested dischazge points; Lafarge does not plan to discharge to either Lupton Bottom Ditch or Big Cry Creek at this time. All maps and the permit document havE: been modified to remove references to discharging to either the Lutpon Bottom Ditch or Big'.Dry Creek. It is Lafarge's understanding, based on the DMG's guidance, that additional discharge points to either of these waterways may be requested in a Technical Revision (TR) after a full engineering analysis of ditch capacity and stability has been completed along with an executed agreement with the ditch company. 2. In responding to Memo Item 4's request for factors determining where water will be discharged, the applicant stated, `7n general, the dewatering water placed in the ditches and/or waterways is only the water removed from that source. "Please explain this statement. Lafarge is no longer requesting discharge into the Lupton Bottom ditch or Big Dry Creek, please see responee to Item 1. LAFARGE NORTH AMERICA INC. -Lafarge Construction Materials 10170 Church Ranch Way, Suite 200, Westminster, Colorado 80021 Telephone: (303) 657-4000 Facsimile: (303) 657-4037