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ROY R. ROMER <br />GOVERNOR <br />*~/^~~ X90 <br />Il\ col <br />t ~~ -,-/r <br />~i <br />~87E1 ~ <br />COLORADO GEOLOGICAL SURVEY <br />DEPARTMENT OF NATURAL RESOURCES <br />715 STATE CENTENNIAL BUILDING - 1373 SHERMAN STREET <br />DENVER, COLORADO 60203 PHONE 13031 866-2611 <br />MEMORANDUM <br />TO: Jim Pendleton, Supervising Geologist, <br />Mined Land Reclamation Division <br />FROM: Wm. Pat Ro ers, Colorado Geological Survey <br />q~i..~ <br />DATE: January 18, 1990 <br />III IIIIIIIIIIIIIIII <br />999 <br />JOHN W ROLD <br />D~RECT00. <br />SUBJECT: SEISMIC SAFETY PROVISIONS FOR BATTLE MOUNTAIN RESOURCE~~, <br />SAN LUIS PROJECT <br />Per your request, I have reviewed pertinent parts of this applical:ion on <br />subjects related to seismicity. I have also had informal discussions with you <br />and Steve Renner and other MLRD staff and participated in two meei:ings with <br />Battle Mountain Resources and their geotechnical consultants. <br />In addition to the project-oriented seismicity study by Dr. Glass that was <br />submitted by Battle Mtn Resources I have consulted several articles and <br />sources, especially having to do with selection of a "pseudostatic <br />coefficient" for projects. These will be listed at the end of this <br />memorandum. My specific comments and recommendations are listed below: <br />1.) The data used, procedures followed, and analyses and recommendations <br />presented by the applicant are appropriate and are adequately <br />conservative if the proposed dewatering system performs as projected. <br />2.) Because the seismic performance of the tailings empoundment is highly <br />dependent on liquefaction not occurring on an extensive scale it is <br />recommended that the proposed piezometer readings and density <br />determinations be specified and the results analyzed and reported <br />periodically to MLRD. This report should specifically compare actual <br />performance of dewatering to those predicted in the designs. <br />3.) There is a third item that was discussed but not resolved at our <br />meeting v.~ith the applicant on January 16th. This does not pertain to <br />the seismic safety of the empoundment but of the processing <br />facility. Given the acknowledged potential seismicity of the site it <br />would seem essential that the facility be designed for at least UBC <br />Seismic Zone 2 (this would be about .15g bedrock acceleration). <br />There was uncertainty on the point by the applicant at ou^ last <br />meeting as to what parameter was used. The more conservative <br />zonation is needed because of personnel and hazardous materials <br />safety considerations. Clarification is needed on this point. <br />G E O L O G Y <br />STORY OF THE PAST... KEY TO THE FUTURE <br />