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1 MINREC, INC. Page 2 NORTH THOMPSON CREEK MINES 1991 AHR ' GROUND WATER QUALITY ' The results of monitoring wells D-lA and D-2A which are lo- cated near the toe of the refuse pile are presented in Appendix II. D-lA is directly below the refuse pile and D-'LA is 200 feet ' to the west of D-lA. Monitoring results for prior years are sum- marized by quarter to make it comparable to the current monitor- ing schedule. ' Graphs have been prepared which show quarterly water level and conductivity measurements for both wells. The water level measurements for the ,year were consistent with prior years data. ' The conductivity measurements were also consistent with prior years. The pH measurements for the wells were similar to prior years monitoring. ' MINE FLOWS ' Water from the No.l Mine continued to be treated and dis- charged to North Thompson Creek during the year. During Septem- ber 1989 a third settling pond was constructed on site to handle ' the No. 1 Mine water. The new pond is referred to as the long pond. The additional settling time provided by the long pond is adequate to a11oTa the iron to settle from the mine water and be ' in compliance for discharge into North Thompson Creek. No chemi- cals have been added to the mine water since the long pond was put in service. The long pond tiaorked very effectively during 1990 & 1991. During 1991 cattails and algae flourished in the ' long pond which assisted in the treatment process. All of the water flowing into the No. 1 Mine is being al- ' lowed to flow out of the mine into the treatment ponds. Measure- ments of the water level in the mine show that the level of water inside the mine has been stable during the year. ' The No. 3 Mine continues to discharge water which is piped from a point source inside the mine. The mine is also filling caith water. The rate at which the mine is filling has slowed ' significantly during the past year. In the preceding 12 months the mine has filled at a rate of 0.10-feet per month. Aefore the mine discharges it must fill another 9.3 feet. If the mine con- ' tinues to fill at the 0.10-feet per month rate, it will be full to the point of discharge in about 93 months. It noia seems pos- sible that the level of the water in the mine may stabilize below the elevation of the portal. A table of the No. 3 Mine water level measurements and a graph which shows the increase in water level over time are presented in Appendix III.