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<br />999 STATE O~ COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department o(Nal ural Resources <br />131 3 Sherman St., Room 215 ~I~ <br />Denver, Colorado 80203 <br />Phone: 13031 866-3567 <br />FAX: 1303) 8J2 ~8I06 ~CCE ICI ' C DEPARTMENT OF <br />.1i'.. G ~ t <br />April 27, 1998 ` C ~ ~ , ^ ~ ~UR~ <br />Mr. Alan Cox Dir.~sion of Minerals l+~~o~-. RnY Romer <br />Governor <br />Manager -Environmental Affairs lames. Lo~nnead <br />Homestake Mining Company Executive Duecior <br />650 CallfOrnla Street .htichaei B. tang <br />San Francisco, California 94108 Division Ducclor <br />RE: Bulldog Mine, File M-77-215, Technical Revision No. 7, Stipulation No. 2, Water Monitoring <br />Plan after Portal Seal Installation <br />Dear Mr. Cox: <br />The Division has reviewed the 9360 Level Adit Closure Monitoring Plan submitted on April 22, 1998 <br />by Water Management Consultants, Inc.. Comments regarding the monitoring plan are listed below. <br />Please respond to these comments by May 15, 1998. <br />1 . Due to the lack of knowledge and detail regarding the groundwater flow rates and paths in the <br />portal area, tracer detection monitoring at the Windy Gulch weir box will be required daily for <br />the first month after closing the portal seal valve. Weekly monitoring wilt be required for the <br />following three months, decreasing to monthly monitoring after that time. <br />2. During the daily flow rate measurement for discharge to the infiltration trench, when in <br />operation, monitoring for evidence of the tracer must be conducted. <br />3. If tracer is detected in influent to infiltration trench, from discharge or seepage of the mine <br />water pool, and water is detected in the vadose zone piezometers, the water in the piezometers <br />must be checked daily for evidence of the tracer. This monitoring must take place while the <br />trench is in operation, continuing for two weeks after flow to trench ceases. <br />4. The Division must be notified, within 48 hours, if evidence of the tracer is found in either the <br />vadose zone piezometers or at the Windy Gulch weir box, or if the adit seal pressure monitoring <br />gauge indicates hydraulic pressures greater than 11 p.s.i.. <br />5. Division of Minerals and Geology concurrence, that conditions at the 9360 Portal have <br />stabilized, will be required prior to initiation of the Long Term Adit Monitoring Plan (revised as <br />per the above comments). <br />Please direct your response, and all future permitting correspondence regarding the Bulldog Mine, to <br />my attention at the Durango Field Office. Allen Sorenson will be contacted by me, far assistance in <br />technical review, when necessary. <br />Homestake Mining Company has, in the past year, initiated changes to operations at the Bulldog Mine, <br />