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Environmental Protection Facility Certification <br /> Henderson Mill — Permit No. M-1977-342 <br /> Technical Revision No. 26 <br /> Sand Seam Mitigation Project <br /> The Sand Seam Mitigation Project was approved as Technical Revision No. 26 to Mill Permit No. M- <br /> 1977-342 on May 11,2015. The project is located at Climax Molybdenum Company's Henderson <br /> Mill in Grand County. The project involved construction of an inclined cutoff layer constructed in an <br /> open cut excavation on the slope located between the Ultimate Canal and the tailing impoundment. <br /> Construction included covering the excavated slope with a 30 mil PVC geomembrane underlain by a <br /> layer of 12 ounce per square yard (oz/sy) non-woven geotextile for puncture protection. The <br /> geomembrane was covered with a one-foot minimum thickness protective sand layer and <br /> compacted fill material with a minimum width of 25 feet. <br /> The Henderson Mill and contractors have substantially completed construction of the project. The <br /> project was designed by URS Corporation to mitigate potential seepage through siltstone and <br /> sandstone bedrock units (sand seams) along the north side of the tailing impoundment. <br /> Modifications to the initial design have been reflected in the construction record drawings signed <br /> and dated December 16, 2015. <br /> URS Corporation was responsible for the design and construction oversight of the project with <br /> construction by Henderson Mill. The project was completed in general conformance with the <br /> approved design as submitted to the Division of Reclamation, Mining, and Safety. The statement is <br /> based in part on information provided by others. <br /> ;� Ll <br /> James W. Babcock, P.E O�O�ADU F�`!c�' /Z//6 '2 <br /> URS Corporation �• Date <br /> Colorado PE No.39477 <br /> ?O ►L�iG IS•• � <br /> ss�ONAt��G� <br />