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F)� <br /> November 28, 2016 <br /> Michael Cunningham <br /> Colorado Division of Reclamation, Mining and Safety <br /> 1313 Sherman Street, Room 215 <br /> Denver, CO 80203 <br /> RE: Lyons Quarry; DRMS File No. M-1 977-141; Technical Revision No. 2; <br /> Verification of Grading Plan <br /> Dear Michael, <br /> This letter is to verify that the slopes and overall configuration shown on the grading plan presented <br /> in Technical Revision No. 2 meet the geotechnical specifications of the 2008 Kleinfelder Summary <br /> Report of Engineering Stability Analysis(Kleinfelder Report). The Kleinfelder Report was prepared <br /> under my direction as the Project Manager and Lead Geotechnical Engineer for the Lyons Quarry <br /> Project. <br /> The Kleinfelder Report states that the existing highwall and rock slopes can be left in place with no <br /> modifications where they will be completely covered by stable fill slopes. Regarding the fill slopes, <br /> the summary report states that existing fill slopes and future constructed fill slopes can be graded to <br /> a final configuration as follows: <br /> Bench Slope Angle 26.6 degrees or 2H:1 V <br /> Maximum Bench Height 50 feet <br /> Minimum Bench Width 15 feet <br /> Maximum Overall Slope Height 150 feet <br /> Regarding rock slopes that will remain exposed, the final reclamation slopes can have the following <br /> configuration: <br /> Fountain Formation laid back to a single overall slope angle of 1.5HA V(33 degrees). <br /> Rockfall catchment berm on minimum 20-foot-wide bench, constructed at the toe of the Fountain <br /> Formation and on top of the dacite sill at the contact of the two units. <br /> i <br /> p0'R< <br /> Sincerely, O0 8•(�'`T <br /> H DR V / <br /> 30656 <br /> John P. Ballegeer, PE, PG • <br /> Senior Geotechnical Design Engineer �OnjALENG <br /> hdrinc.com <br /> 1670 Broadway, Suite 3400,Denver,CO 80202-4824 <br /> (303)764-1520 <br /> 1 <br />