1988-04-11_PERMIT FILE - C1981008A (17)

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outside these multiple year ranges will be considered to be possible effects from pit pumpage. Water level drops in monitoring wells outside the projected zones of pit pumpage drawdown will be considered suspect unless a consistent deepening trend develops. Mining impacts on ground water quality will be compared against the multiple year baseline monitoring ranges established for each chemical parameter monitored at each site. Because a number of variables can affect water chemistry, only significant increases or consistent trends will be considered as possible impacts from mining. Trilinear and Schoeller diagram plots of well water chemistry will also be evaluated to identify water quality changes or degradation trends. Spring Flows and Quality. Spring flows and quality changes at spring monitoring sites will be compared to ranges developed from multiple-year baseline monitoring data. Significant flow or quality deviations from the multiple-year ranges not explainable by climatic fluctuations will be considered to suggest impacts from mining. Surface Water Monitoring Plan. Introduction. Determinations of the probable hydrologic consequences (PHC) of mining have been made by including detailed analyses of historical surface water quality data (see Tab 17, Probable Hydrologic Consequences). Table 18-1 presents the surface water sites used to substantiate the significance findings presented in the PHC analysis and for measuring potential future mining impacts. The following section summarizes how future mining impacts on both surface water quality and quantity will be evaluated using monitoring data collected at sites established in both the Nucla Mine and Nucla East mining areas. Surface Water Quality. Future impacts on surface water quality will be evaluated by using trending analyses. Mining activities at the Nucla Mine began prior to the onset of collecting surface water quality data (1979), hence, no true baseline data exists for comparison purposes. However, a well documented but short record of surface water quality has been collected during baseline studies conducted at the Nucla East area. Regardless, the significance of impacts will be evaluated by analyzing for prominent trends of changing chemical concentrations over time. Consistently increasing concentrations of chemical parameters will be considered to suggest mining impacts. Data collected at sites located above mining (most upstream) along Tuttle (SW-N1) and Calamity Draws (proposed surface water monitoring site, see Tab 15, Hydrologic Monitoring Program) will be used for investigating whether any future observed trends are natural or result from mining. 18-6 Revised 04/11/88