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,' <br />Henderson Hine and Mill <br />1991 Annual Report <br />Permit No. M-77-342 <br />January 16, 1992 <br />Page 2 <br />AREA 9. 20, 21 <br />Excessive flow volumes during spring runoff caused isolated <br />failures of the tailing basin interceptor ditch resulting in <br />limited abilities to bypass fresh water around the basin. Response <br />and repairs to the problems began in May. Approximately ?900 feet <br />of 42" HDPE pipe, two inlet structures and two energy di:~sipators <br />were installed in the steep sections of the ditch. Three <br />additional water diversion points were installed along the ditch. <br />These diversion points, that convey fresh water from the ditch to <br />the tailing basin, are designed to eliminate freezing problems and <br />allow isolation of turbid flows if necessary. A secondary means of <br />fresh water diversion for use during high runoff periods was <br />installed from the ditch to the emergency spillway line of the <br />decant structure. The cost for these repairs was approximately <br />$240,000. <br />Mined Land Reclamation Division personnel inspected the Mine <br />and Mill site in December 1991. Inspection reports were received <br />in January 1992. <br />Signs were installed at the Mine and Mill sites as rec;aired by <br />the recently enacted Rule 6.7 (1). <br />Tailing deposition and water acreage totaled 817 acres at the <br />end of 1991 and did not exceed the forecast. <br />SURETY <br />The biennial recomputation of the estimated Henderson Mine and <br />Mill reclamation costs for 1991-1992 was completed in February 1991 <br />and submitted to the Mined Land Reclamation Division as part of the <br />1990 annual report. Therefore, no update is included in this <br />annual report. <br />Please contact me if additional information is necessary. <br />Sincerely, <br />'~.7. J. ones <br />Environmental Manac~er <br />