2005-02-11_REVISION - M2000016 (2)

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INTEROFFICE MEMORANDUM COLORADO DIVISION OF MINERALS AND GEOLOGY 1313 Sherman St., Rm. 215 Denver, CO 80203 TO: Gregg R. Squire ~ n/~ FROM: Kathleen L. Sullivan, P.E. ~ d~-~-~ SusJECr: M-2000-016, Lafarge West, Inc.: Riverbend Operation, AM-01 DATE: February 11, 2005 CC: Harry Posey, DMG (via e-mail); Kate Pickford, DMG (via a-mail) This memo contains adequacy review comments from the Division's hydrology and slope stability review of the Lafarge West, Inc.: Riverbend Operation 112(c) Amendment (AM-01) Application, File No. M-2000-016. The applicant may contact me with any questions at (303) 866-4060. The applicant should be aware of and acknowledge that Stipulation No. 1 to the original permit M-2000-016, regarding the 400-feet setback from the top of the bank of the South Platte River, will remain in effect for and apply to the amended area. Maps showing mining within 200 feet of the riverbanks need to be amended. Alternatively, as stated in berms to be left at the conclusion of mining" could allow mining closer than 400 feet. 2. All maps must be amended to show all water features and other relevant features, especially the continuity of creeks, rivers, and ditches that may be affected by this operation, even if they are more than 600 feet from the proposed permit boundary. For example, on Exhibits C1, C3, and F2, show the South Platte as it runs through the Olgilvie and Von Struve properties of Section 18 and Othe Fort Lupton Bottom Ditch and Big Dry Creek through the lower half of Section 13. 3. The applicant must ensure compliance with all other agency requirements for the expanded operation, such as updated Substitute Water Supply Plan approvals and current Well Permits, CDPS permits, etc. prior to engaging in related operations at the site. Rule 6.4.4 EXHIBIT D - Minina Plan 4. The submitted mining plan indicates that water resulting from dewatering and storm water runoff will be discharged into the South Platte River, Big Dry Creek, or into the Lupton Bottom Ditch or the Brighton Ditch, or into adjoining cells. The applicant must indicate what factor(s) will determine whether water is discharged into which of the waterways, as well as specify the maximum discharge rate into, the base and maximum flow of irrigation water in, the capacity of each of the ditches, and indicate whether these structures can accommodate the increased loading. The applicant must provide the Division copies of alf necessary agreements with ditch owners prior to discharging to