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Mr. Tom Schreiner, Division of Minerals and Geology Mamh 23, 2005 Page 9 ~~ GVIL RESOURCES, LLC the groundwater surface had an approximate northwest bearing. Refer to Appendix B of the Groundwater Model Report for further details. 21. Please characterize the seasonal fluctuations in the groundwater table in the affected land and surrounding area based on the affects snowmelt recharge, inigation water users, domestic water users, the South Platte River fluctuations, and any other significant inputs. Such characterization should adequately describe the typical fluctuations currently experienced over the course of a full 12 months. The seasonal fluctuation range is presented in Figure 6a of the Groundwater Model Report and observed water levels have been collected for every season. Modeling was performed with precipitation recharge (snow and rain) and the South Platte River was assigned an elevation at the location surveyed and this elevation was interpolated (using a river slope of 0.17%) upstream and downstream. Crop consumptive use was used to simulate an overall stress (such as well pumping) on the system. 22. Please revise Figure 2a or provide an additional figure to show a typical cross section of the Lupton Lakes Resource and surrounding area with the following features: South Platte River, groundwater table affer mining, existing ground topography, Fulton Lateral Ditch, existing water table, estimated lake water surface, limits of mineable resource. (Attached is a copy of such cross section provided for the Md6 Pit; Permit M-1986-079f. We have revised and attached Figure 2a-R. 23. The mining conditions specified on page 8 of the report and used during the model simulation to predict the potential groundwater effects will need to be clarified and possibly rerun based on maximum disturbance criteria that are clear and enforceable. For example, the applicant will need to clarify the maximum number of acres of pit excavation to be expected at any one time throughout the operation and the de-watering requirements to maintain such a dry pit excavation. The applicant will need to be specific in terms of specifying the inputs used during the model simulation including volume and rate of pumping required, the length oftime ofpit de-watering required for such disturbance unfit the clay liner construction is completed, the linear footage of completed liner construction per cell(s) and expected groundwater inflows for such area, and the linear footage of unlined pit wall per cell(s) and expected groundwater inflows for such area, and the acreage of unlined pit floor. 1(the applicant elects to run the model both with and without mitigation measures to be employed, the applicant should be specific in quantifying the mitigation measures to be employed. Following such assessment, fhe applicant will need to describe the lateral and vertical extent of the predicted groundwater impacts and the various offsite structures that wi116e affected, ie: high production inigation wells, shallow alluvial domestic wells, deep aquifer domestic wells, and wetlands dependent on shallow alluvial groundwater. As discussed in the Groundwater Model Report, the dewatered mining area was modeled with constant head nodes and allowed to drawdown to steady-state condition. This is a tar more conservative approach to estimating drawdown affects then modeling the mining phases with pumping wells. However, we understand the Division's concern that the entire site could be disturbed. As a result, we have requested the following permit conditions: • The site shall be mined in 20-25-acre sections as depicted on the Mining Plan Map.