Laserfiche WebLink
A.OM <br />January 26, 2018 <br />Mr. Brandon Guite <br />Climax Molybdenum Company <br />Henderson Mill <br />19302 County Road 3 <br />Parshall, Colorado 80468 <br />AECOM 303-694 2770 tel <br />6200 s Quebec St. 303 694 3946 fax <br />Greenwood Village, Colorado <br />80111 <br />WWW.aeoom com <br />Subject: 3 Dam Buttress Design, Henderson Mill Tailings Dam, near Parshall, Colorado <br />Dear Brandon, <br />AECOM Technical Services, Inc. (AECOM) prepared this letter report, which presents the design and <br />construction drawing for the buttress of 3 Dam to date. Presented below is a brief background, <br />summary of our design, and construction drawings. <br />INTRODUCTION <br />AECOM was contracted by Climax Molybdenum Company- Henderson Mill (Henderson) to analyze <br />and design stabilization measures (buttress) for the Henderson Mill No. 3 Tailings Impoundment <br />(3 Dam) under design seismic loading conditions. This report summarizes our analyses and design <br />recommendations to date. <br />A Technical Review Board (TRB) has been convened to review the dam and geotechnical/civil <br />analyses for the design of 3 Dam. The TRB consists of the following members: <br />• Norm Abrahamson, Ph.D. (University of California Berkeley) <br />• Todd Martin, P.Eng. (formally a professional at BGC) replaced by Roy Mayfield, Ph.D., P.Eng <br />in 2016 <br />• Peter McCreath, Ph.D., P.Eng. (Clear Water Consultants) <br />• Norbert Morgenstern, Ph.D., P.Eng. (University of Alberta) <br />The TRB geotechnical comments and recommendations have been incorporated by the design team <br />and have been included as part of this buttress design. <br />PROJECT LOCATION AND BACKGROUND <br />Henderson Mine is an underground molybdenum mine located in Clear Creek County, Colorado with <br />a mill located in Grand County, Colorado near the summit of Ute Pass. The mine and mill are owned <br />and operated by Climax Molybdenum Company, a division of Freeport-McMoRan, Inc. Henderson <br />Mill operates a single tailings storage facility composed of two active tailings dams. The largest dam, <br />also known as 1 Dam provides the primary containment. A smaller dam located south of the main <br />dam, known as 3 Dam, combined with 1 Dam, result in the singular dam crest. Photo 1 shows both 1 <br />Dam and 3 Dam. Another tailings dam known as 2 Dam has been fully inundated and is contained <br />within the impoundment area. AECOM is the Engineer -of -Record for the tailings dams. AECOM and <br />its heritage firms (URS Greiner, Woodward -Clyde Consultants) have been engaged with the tailings <br />dam design, operation, and monitoring at Henderson from the outset in the 1970's. <br />MiOCSVIM*UIWTRMM14M HENS_BLA&i bDaprwaEln'DRMS RopdgRepoMardwaon_ 3 Dam SWron Daalpn Ledw Rpwt Rw B_FYulAm <br />