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Mr. David Berry October 26, 1988 Page 7 CYVCC RESPONSE: The definition for baseline levels is further clarified in the AHR. The clarification advises that there is insufficient data to indicate whether the level which is significantly higher than background levels in other areas of Twentymile park is die to natural causes or is related to mining. Given this clarification a further explanation of the statement is not required. MLRD CONCERN: Spoil Wells Two spoil wells are monitored; one of which has never produced water. As discussed previously, we recommend that another well should be installed to replace the dry well (008-SP-4A). The well 008-SP-5A exhibits relatively elevated values for electrical conductivity, total dissolved solids, sulphate, iron and manganese. It should be noted that the most recent mercury and cadmium values indicate an increase relative to the previous values. CYVCC RESPONSE: As stated previously, CYCC does not believe a replacement spoil well is warranted at this time. In reference to the water quality data, the electrical conductivity, total dissolved solids, sulphate, iron and manganese concentrations are within the range one can expect from water samples obtained from spoil wells. In regards to cadmium, the most recent concentration of 0.4 ug/1 in Well 008-SO-5A is well below the previous detection limits of S and 20 ug/1, and is not an increase from previous concentrations. You are just seeing the differences in detection limit reporting concentrations. Finally, the most recent mercury concentration of 0.3 ug/1 is only slightly above the detection limit of 0.2 ug/1 and is not of significant concern. This one data point does not indicate a trend. MLRD CONCERN: Alluvial Wells Two alluvial wells are monitored at Mine No.3; both indicated relatively elevated values for electrical conductivity, total dissolved solids, sulphates, iron and manganese. The January 1987 measurement for mercury (Well 008-AV-1) exceeds the receiving stream standard. A review of the electrical conductivity data for well 008-AV-2 indicates a possible increasing trend that may or may not be explained by recent low flows. Additional study will be conducted to assess this possible trend and to better quantify the relationship between the alluvial wells and the surface water system.