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Mr. Rick Mills - 4 - July 7, 1988 4) The detection limit used for mercury is consistently above the material damage standard. The detection limit should be lowered to allow comparison with the .00005 mg./1. (total recoverable) standard. Please discuss this problem, and if a lower detection limit is not possible due to some laboratory analysis constraint, an explanation must be provided. Bedrock We11s Two wells are monitored at mine No. 3. Both wells have exhibited electrical conductivity, total dissolved solids and sulphate levels above receiving stream standards. The most recent iron values for well 008-77-58 are lower than previous measurements, which had been higher than receiving stream standards. The 1987 manganese concentration in well 008-79-6 approaches the receiving stream standard of 0.174 mg:/1 (dissolved). The AHR concludes that the baseline total dissolved solids level for these wells is about 1,000 mg./1. It is our understanding, however, that mining predates the data base for these wells: Please provide a brief explanation to substantiate the baseline estimate: Spoil We11s 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. 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-7) 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: Spoil SDrinas Two springs were sampled during the 1986-1987 water year. These exhibited relatively high values for electrical conductivity, total dissolved solids (M3-87-1), sulphate (~i3-87-1), silver (M3-87-1 ), zinc (M3-87-2), iron and manganese. The suspended solids concentration is relatively high for M3-87-2. We recommend that when samples are collected for low flow sites such as these, the sample should be filtered. This should be documented in the data base to avoid any confusion during the data analysis phase.