2005-07-13_REVISION - M2000016 (39)

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~LAFARG E NORTH AMERICA Construction Materials 4. The submitted mining plan indicates that water resulting from dewatering and storm water runoff will be discharges 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 discharge 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. Lafarge will not discharge into irrigation ditches prior to executing an agreement with the Ditch Company. Lafarge has spoken with the Lupton Bottom Ditch Company and has agreed to have agreements in place one year prior to dewatering activities in cells adjacent to the ditch. The maximum discharge rate, the base and maximum flow of irrigation water in, the capacity of each ditch, and an engineering analysis to determine the effects of loading will be calculated during agreement negotiations. The Ditch Company will determine what is acceptable in the agreement. The Lupton Bottom Ditch runs through Big Dry Creek along portions, therefore impacts to Big Dry Creek will be assessed during Lupton Bottom agreement negotiations. In genera], the dewatering water placed in the ditches and/or waterways is only the water removed from that source. Lafarge will not discharge more water than a ditch, stream, or river can accommodate; al] dewatering discharges will be assessed, monitored, and modified as necessary during operations. The Colorado Department of Health and Environment, Water Quality Control Division, will also provide a measure of control over discharge through our CDPS permit. 5. The slope stability analyses conducted to determine mining and stream offsets used n %:I slope angle, whereas the Mining Plan indicates mining may occur up to vertical. The analyses also did not model surcharge loads from topsoil/overburden piles. Offsets needs to be recalculated with these inputs included. The Mining Alan has been amended to reflect mining to a %:1 slope angle, Lafarge will maintain the''/z:l mining slope and will not mine to vertical. All overburden and topsoil piles will be outside the offset limits and will not affect the limits; Exhibit C has been modified so all stockpiles are located outside the specified offsets. 6. The applicant needs to provide the Division with drill hole records so we can check the slope stability modeling. Please find enclosed the spreadsheet titled "Borehole Data" which provides the logged depths of all drill holes within the Riverbend amendment area. The map titled "Borehole Locations" shows the corresponding location of each drill hole. LAFARGE NORTH AMERICA INC. -Lafarge Aggregates, Concrete & Asphalt 10170 Church Ranch Way, Suite 200 Westminster, Colorado 80021 Telephone: (303) 657-4000 Facsimile: (303) 657-4037