2005-01-03_REVISION - M1999120 (5)

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Ms. Lynn Mayer January 3, 2005 Page 6 TABLE 1 Water Wells North of LGE Ft. Lupton Pit in Potential Groundwater "Shadow"~ Permit No. Owner z Use Yield (gpm) Depth (ft) SWL (ft) Predicted Reduciion in Saturated Thickness LGE Only All Pits 6639 Blue Ribbon Nursery I 1,200 28 6 11 16 6638 Hein I 1,100 30 6 6 8 6637 Hein I 1,200 29 10 7 11 185928 Bearson O 15 53 15 5 7 181568 Hein D 15 42 4 3 5 ~ See Drawings 4 and 5 for locations. z I = Irrigation; D = Domestic. Recommendations Continue monitoring. It is recommended that LGE continue to measure groundwater in the existing monitoring wells (Drawing 1) throughout the life of the existing mine. Groundwater should also be monitored throughout the life of the expansion azea, as discussed later in more detail. The data should be evaluated prior to any mining in the expansion azea to determine the following: Average growing season (May 15 through October 1) and non-growing season groundwater levels. • The range of growing versus non-growing season levels. Waiting until just prior to commencement of mining of the expansion azea will allow for more data to be collected. Pre-mining data are appropriate since they represent "baseline" conditions without the expansion, during which there have been no reported effects. Precipitation and irrigation should be considered when analyzing the baseline groundwater data. 2. "Trigger development." It is recommended that a "trigger" be developed to determine impacts to groundwater from the LGE expansion. The trigger should be based on the data and consider natural groundwater fluctuations. The trigger should also require documentation of a complaint since implementation of mitigation measures, as subsequently discussed, is relatively expensive.