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Erica Crosby <br />Division of Minerals and Geology <br />March 1, 2005 <br />Page 3 of 5 <br />Based on the most recent survey, we know the elevation of the existing pit floor relative to the <br />monitor wells (see Exhibit G). We also know that the ground water table in this area has a fairly <br />steep gradient (approximately 3%) and becomes deeper to the east and south. Our data reveals <br />discrepancies of up to 14 feet (on the steeper, non-mined slopes) between surveyed points and <br />USGS-derived contours. Due to this potential vertical error, and the likely increase in groundwater <br />elevation during the spring runoff and irrigation season, the applicant proposes to ensure that <br />mining does not come within 5 vertical feet of ground water via the following commitments: <br />• The operator will not mine deeper than 26 feet above the mapped oround water table <br />elevation as shown on Exhibit G. The revised reclamation contours for this proposal are <br />shown on Exhibit F. If the applicant or operator gathers additional data proving that deeper <br />mining will not encounter ground water, a Technical Revision will be submitted. <br />If the operation encounters groundwater, the operator will immediately backfill and cease <br />operations within 5 vertical feet of encountered ground water. <br />• The applicant will submit monthly monitoring data to the Division as part of the Annual <br />Report. <br />9) Monitor Well #3: Monitor Well 3 is located within Phase 3, which is not expected to be mined for at <br />least 12 years. The well will be officially closed as required by the State Engineer's Office prior to <br />disturbance in Phase 3. When mining activities commence in the vicinity, the PVC pipe located <br />above the water table will be removed and disposed of. The pipe below the mine floor will remain, <br />and will have already been gravel-filled per SEO requirements. <br />10) Monitor Well Reclamation Plan: The applicant is in the process of permitting these wells with the <br />State Engineer's Office (SEO) for long-term use as monitoring wells. Upon completion of mining or <br />removal of the wells, the wells will be closed and an abandonment report submitted per SEO <br />regulations. If the Division has the authority to bond for wells regulated by the SEO, the following <br />information can be used: <br />MW # Total De th Well Diameter Com letion T e <br />1 60 feet 6.5 inches Schedule 40 PVC <br />Casing (plain and <br />erforated <br />2 19 feet 6 inches 7.5 inches same <br />3 43 feet 6 inches 7.5 inches same <br />4 26 feet 10 inches 7.5 inches same <br />5 45 feet 7 inches same <br />11) Impacts to Springs: The springs in this area are alluvial and reflect the ground water table <br />elevation at that location. To date, we have surveyed the vertical location of one spring located <br />southeast of the existing pit (see Exhibit C-3). The spring is located 110 vertical feet below the <br />existing pit floor. The remaining springs are all located on the eastern, non-mined slopes of the <br />property, and their approximate locations and elevations have been used to construct the water <br />table contours shown on Exhibit G. Even with potential discrepancies between actual elevations <br />and contour elevations, the commitment to stay 26 feet above the mapped water table is protective <br />of the springs. Additional surveying of the springs may be submitted as part of a Technical <br />Revision if the applicant wishes to mine deeper in the future. <br />