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_ Lorertcilo Canyon Minc -Groundwater Technics( ReOOn <br />• Groundwater in the alluvium at the site is characterized as being under unconfined, water table <br />conditions. The water table gradient in the Lorencito Canyon alluvium is to the north with the <br />gradient from the respective side canyons from up canyon down toward Lorencito. Gradient <br />averages 0.027 ft/ft in the alluvium. A potentiometric surface map of Lorencito Canyon is <br />presented as Map 2.04.7-3. Hydrographs of the alluvial well water elevations are included as <br />Appendix GW-5. Aquifer characteristics of the alluvium were determined via slug testing. A <br />summary of the data from these wells is presented in Table GW-11. <br /> <br />• <br />TABLE GW-11 <br />LORENCITO CANYON MINE <br />SUMMARY OF ALLUVIAL WELLS SLUG TEST RESULTS <br />Well Hydraulic Conductivity <br />(ft/da) Standard Error <br />(from ft/min values) <br />LC1 1.19 +/- 7.2708E-005 <br />LC2 149.8 +/- 1.0784E-003 <br />LC3 3.68 +/- 9.4793E-004 <br />LC4 12.55 +/- 7.6503E-004 <br />JC1 3.80 +/- 2.6025E-004 <br />PC1 0.43 +/- 1.9337E-005 <br />CC1 30.5 +/- 9.5843E-004 <br />AC1 38.74 +/- 9.1286E-004 <br />CWC1 31.80 +/- 4.0383E-004 <br />CWC2 22.72 +/- 9.5213E-004 <br />Statistical analyses of the hydraulic conductivity was conducted to determine the average hydraulic <br />conductivity for the alluvium. The range of the data was from 0.43 to 149.8 fdday. The mean <br />value calculated for the data was 29.52, with a population standard deviation of 42.27. This <br />indicates a wide variance in the data from the alluvial wells. Consideration of the individual <br />standard error from each data set (derived during analyses) indicates that each well analysis has <br />a fairly high degree of certainty; therefore, the alluvial properties probably vary widely within the <br />alluvium itself. All values for the alluvium fall within ranges typical for clean fine-grained sand <br />to coarse grain sand (Heath, 1983). Storativity values for the alluvium cannot be calculated from <br />the testing performed. Storativity in this case is estimated from literature sources to be 0.1 to 0.3 <br />(Heath, 1983). Copies of all analyses and data from the slug tests performed at the site are <br />included in Appendix GW-6. <br />Groundwater 6"I$\Dttember 9, 1996 35 <br />