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HON'AKE • O ALAN D. COX CORPORATE MANAGER, ENVIRONMENTAL AFFAIRS iii iiiiuiiniii iii • Received JUN l q ~sss 14 June, 1999 State of Colorado Division of Minerals and Geology Durango Field Office 484 Turner Drive, Suite F701 Durango, CO 81301-7910 ~~ ~~ Frg~ Ofl of Mlnerab g rCe RECEIVED PUB~V~R OFF ~oioQy JUN 21 1999 F/~~C~ yICF C~ ~ Division of Minerals 8 Geology ~I T~. ~~~~ 7~z js Attn: Mr. Steve S. Shuey, Reclamation Specialist ~~n: p ^/N, rrnc 'C~ P~~ RE: Bulldog Mine Reclamation Proiect May, 1999 Monthly Monitoring RepoJrt /oor`~J Dear Mr. Shuey: Pursuant to the Technical Revisions to the Reclamation Permit for the Bulldog Reclamation Project, this is the eighteenth monthly report pertaining to 11 installation and operation of an infiltration trench to accommodate seepage from the 9360 adit, and 21 closing the valve at the 9360 adit plug. The Division of Minerals and Geology IDMGI, in a letter dated March 8, 1999, issued a conditional approval for Homestake Mining Company (HMC) to close the valve at the 9360 adit plug. Subsequent to DMG's approval, HMC closed the valve to the adit plug on April 1, 1999. By closing the valve at the adit plug, HMC is committed to the monthly monitoring summarized below in accordance with the approved Technical Revisions. Since closure of the adit plug valve on April 1, 1999, no flow has or is being directed into the infiltration trench. Therefore, as noted in Table 1, the infiltration trench and vadose zone monitoring have been discontinued. The revised monitoring program was initiated in April 1999 as described in the April 1999 monthly monitoring report. Summaries of the monthly monitoring data are presented in Tables 1 and 2, and Figure 1 attached. Based on the required visual inspection around the adit plug, the plug is impounding water behind it with no signs of seepage and/or development of seeps around the portal area. No flow was observed in DT-1 and DT-2 during the monthly sampling activities. As part of this monthly report and in accordance with the 9360 Level Adit Closure Monitoring Plan, dated April 1998, Windy Gulch monitoring was continued during this period. Flow was observed through the WGL Weir during this period and a water quality sample (WGL Weir) taken on May 10, 1999. Analytical data for this sample are attached. The estimated flow through the weir at the time of sampling was approximately 940 gpm. Continuous flow monitoring at the WGL Weir was initiated in April 1999. Figure 2 summarizes the flow through the weir to date. Thank you for your time and attention on this matter. If you have any questions, please contact me in the San Francisco office. Veryery Tru cc: R. Callan, Grants F. Martinez, Alamosa BLM D. Holmer, Colorado WOCD, Denver J. Rowe / S. Randall, WMCI, Denver HOMESTAKE MINING COMPANY 650 CALIFORNIA STREET • SAN FRANCISCO • CA 9<IO8-2]66 (a15) 9818150