2002-09-27_REVISION - M1977436 - Laserfiche WebLink

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RECEdVED September 27, 2002 SEP 2 7 2002 lliuision of Minerals and Geology Erica Crosby AGGREGATE Division of Minerals and Geology INDUSTRIES 13]3 Sherman Street, Room 215 Denver, CO 80203 Re: Brignton Mine -Permit No. M-1977-436 -Amendment Application (AM-02) Response to Adequacy Questions Dear Erica: This letter is submitted in response to your adequacy review questions for the above-referenced amendment application as relayed by your letter dated May 22, 2002. The following responses are numbered in accordance with your comments: Please refer to the enclosed letter to Besharah Najjar, Floodplain Administrator for Adams County, together with Reclamation Plan Map - Exhibit F and detailed drawing of grouted sloping boulder drops, prepared by Aggregate Industries' consultant, Dana Miller of Applegate Group. Ms. Miller's letter and drawings respond to the issues raised by Bryan Kohlenberg of Urban Drainage and Flood Control District. 2. Wetland areas will be established at goundwater level from the land sides of the pit, south and west of the spillway, while pit area adjacent to the river will be open water. Proposed wetland species revegetation will occur on gentle slopes established from the top of higher elevation land side slopes towards the open water area and lower elevation riverside slopes and will not be subjected to deep depths of water during storm events. (See response to Item No. 3 below.) 3. Exhibit E -Reclamation of the amendment application states that all slopes in the North Lake area will be no steeper than 3V:1H. The intent of this statement was to provide flexibility and allow variation in sloping, with the steepest slope to be no Beater than 3V:1 H. The pit perimeter will be established at a 3 V:1H slope, as will slopes of various cells created within the pit for capturing wash fines. While sloping along the riverside of the pit will retain 3V:1H slopes, sloping from land sides of the pit and fines cells will generally be developed with more gentle sloping, ranging from10V:1H to 6V:1H, as wash fines are pumped into these areas from the processing plant. 4. During your site visit on May 29, 2002, I believe that you indicated you would accept a narrative description of the relationship of the riverside berm spillway and pit floor to the river in lieu of depicting elevations on the reclamation plan map. Based on information obtained from the Urban Drainage Profile of this area and existing topography, pre-berm top of bank elevations along the north pit range from 4985 upstream to 4975 downstream. The proposed removal of 4 feet from the existing riverside berm is intended to lower this berm to pre-mining grade, which is assumed to be the top of bank elevations. Existing topogaphy near the north cell spillway compared to the Urban Drainage Aggregate Industries West CaMral Region, Inc. 3605 South Teller Street Lakewood, CO 80235 Connie Nickle Davis, Suppon Services P. O. Bax 337231, Greeley, CO 80633 970-336-6526 Fax: 970-378b856 Telephone: 303-985-1070 An Equal Opportunity Employer