2024-11-22_REVISION - M1999120 (4)

Home Browse Search

Groundwater Quality Monitoring Plan CI gradients with time that could affect water flow in the aquifer. Therefore, there may be a need to update the baseline data over time because the data has changed due to a particular change in natural conditions at the mining site. It may be impractical to conduct extensive statistical analysis on every water quality parameter tested. A set of select water quality parameters can be used to identify potential water quality degradation. This set of select parameters will be used for statistical analyses and charting and will be approved by DRMS in a TR. After the initial five quarters of baseline data is collected, future sampling will occur annually for the specific parameters. Prior to starting the mining, sampling will be conducted within 90 days. The water quality sample results from future sampling events during the mining activities will be compared to the baseline data. A further in-depth review of the groundwater quality data will be needed to determine whether mining is resulting in the potential for any type of pollution in the aquifer. 4.2 Sampling Parameters The sampling parameters listed in Table 3 are derived from CDPHE— Reg 41 Basic Standards for Groundwater, Tables 1 through Table 4. These parameters are analyzed for all baseline samples. The baseline sample data will be used to determine potential future changes in groundwater quality. 4.2.1 Selection of Parameters The groundwater data obtained from baseline sampling will provide information that can be used to determine the appropriate parameters for statistical analysis, and which parameters should be excluded in future sampling events. The proposed set of parameters will be determined after the baseline data is obtained. The set of parameters will be evaluated on an annual basis and if any anomalous trends develop for parameters, subsequent statistical analysis will be conducted to assess anomalous trends outside the expected naturally occurring water quality variability. 4.3 Statistical Analysis The database of sample analytical results will be preliminarily assessed for representativeness. Any anomalous, or non-representative, water quality data will be excluded from the baseline data prior to conducting the statistical analysis. If data points are excluded, LGE will provide a written rationale to the Division for the exclusion. Once the representative database has been established, the baseline mean and standard deviation for each of the selected parameters will be calculated. The data collected will provide the standard deviation used to establish a control limit(95 % confidence interval VASMOLEN LG Everist Fort Lupton GW Monitoring Plan &ASSOCIATES Page 6 of 7 31