1994-03-23_HYDROLOGY - M1977378 - Laserfiche WebLink

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Sunnyside Gold Corporation March 23, 1994 page 2 The Water Quality Control Division does not agree with this position, and has serious concerns about the monitoring program that has been proposed. These concerns are outlined below. 1) There is no documented plan for how the data will be analyzed, either during or after its collection. Without using statistical methods to analyze the data at the completion of the proposed five year sampling period, it is likely that a simple comparison of pre-plugging against post-plugging data at each individual sampling site will produce widely varying results that will be more reflective of sporadic random variations in loading than representative of overall trends. It is also unclear how the Corporation intends to discriminate between those variations in loading that might be due to seasonal or year-to-year hydrologic conditions and those variations that are actually caused by the plugging project. 2) Without knowing how the data will be analyzed, it is not clear whether or not an adequate baseline dataset has been accumulated. While some additional baseline data may be available after the tunnels are plugged, due to the fact that it will take some time for the mine pool to reach its ultimate equilibrium elevation, only 20% of the originally identified sample sites will be monitored for metals in any given year. Also, the locstien of sites in mlation to the pool elevation will not be a factor considered in the selection of sites to be sampled. Therefore, it is likely that some seeps would only be sampled once before the pool elevation rises above the seep elevation,providing a single data point for comparison purposes. If the pool elevation rises faster than predicted, which has been observed in other plugging operations, the number of sites with multiple baseline observations will be very limited. 3) Again, without knowing how the data will be analyzed, it is not possible to judge whether or not the proposed sampling frequency is adequate. If pre and post-plugging data is to be compared on a site-by-site basis, the proposed frequency of once in five years would probably be inadequate. In order to address these concerns, the Corporation and our Division must come to an agreement upon some basic principles related to the goals of the monitoring program, as well as agreement upon the methods and decision criteria that will allow those goals to be achieved. As an initial effort to identify the central issues that must be resolved,we propose the following goals and supporting objectives be used as a basis for further discussion. A) The overall goal of the monitoring program should be to detect long-term trends in the loading of pollutants to receiving waters, and if required to protect certain individual stream segments, to identify the specific sources of such loading. B) The general approach taken to compare pre and post-plugging loadings must be defined. The sites where loadings will be compared must be determined, as well as the type of statistical analyses that will be used to perform the comparisons. C) The baseline loading condition must be identified. It may be necessary to delay the plugging of the tunnels until enough data has been collected to statistically characterize existing loadings with confidence. The time period for delay is directly related to the statistical analysis, and the Division does not have enough information to propose a specific timeframe. The required sampling frequency should be based upon the overall method of analysis that will be used. It will probably be necessary to perform at least monthly analyses to account for seasonal variations. As data is collected, analyses could be performed to identify when an adequate number of samples has been collected.