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October 19, 2017
<br />Table 5. Well Locations, Depths, and Screened Lengths for Scenario 1
<br />Page 19
<br />Dewatering
<br />Well
<br />Fasting
<br />(ft)
<br />Northing
<br />(ft)
<br />Surface
<br />Elevation
<br />(ft NISL)
<br />Screen Top
<br />Elevation
<br />(ft MSL)
<br />Screen Bottom
<br />Elevation
<br />(ft MSL)
<br />Hole
<br />Depth
<br />(ft)
<br />Screen
<br />Interval
<br />(ft)
<br />Well -I
<br />1330468
<br />350462
<br />7,399
<br />7,150
<br />6,648
<br />756
<br />502
<br />Well -2
<br />1329296
<br />350855
<br />7,442
<br />7,182
<br />6,688
<br />759
<br />494
<br />Well -3
<br />1328028
<br />351120
<br />7,439
<br />7,150
<br />6,697
<br />747
<br />453
<br />Well -4
<br />1326391
<br />351308
<br />7,453
<br />7,182
<br />6,701
<br />757
<br />481
<br />Well -5
<br />1325665
<br />350095
<br />7,450
<br />7,274
<br />6,780
<br />675
<br />494
<br />Well -6
<br />1326753
<br />348766
<br />7,676
<br />7,388
<br />6,891
<br />790
<br />497
<br />Well -7
<br />1327459
<br />348528
<br />7,703
<br />7,401
<br />6,934
<br />774
<br />467
<br />Well -8
<br />1328546
<br />348320
<br />7,681
<br />7,402
<br />6,920
<br />766
<br />482
<br />Well -9
<br />1329510
<br />348826
<br />7,403
<br />7,306
<br />6,828
<br />580
<br />478
<br />Well -10
<br />1330379
<br />347972
<br />7,667
<br />7,366
<br />6,875
<br />797
<br />491
<br />Well -11
<br />1331738
<br />348894
<br />7,566
<br />7,209
<br />6,744
<br />827
<br />465
<br />AVERAGE
<br />748
<br />482
<br />Table 6. Well Locations, Depths, and Screened Lengths for Scenario 2
<br />Dewatering
<br />Well
<br />Fasting
<br />(ft)
<br />Northing
<br />(ft)
<br />Surface
<br />Elevation
<br />(ft NISL)
<br />Screen Top
<br />Elevation
<br />(ft NISL)
<br />Screen Bottom
<br />Elevation
<br />(ft NIS L)
<br />Hole
<br />Depth
<br />(ft)
<br />Screen
<br />Interval (ft)
<br />Well -1
<br />1330468
<br />350462
<br />7,399
<br />7,150
<br />6,648
<br />756
<br />502
<br />Well -2
<br />1329296
<br />350855
<br />7,442
<br />7,182
<br />6,688
<br />759
<br />494
<br />Well -3
<br />1328028
<br />351120
<br />7,439
<br />7,150
<br />6,697
<br />747
<br />453
<br />Well -4
<br />1326391
<br />351308
<br />7,453
<br />7,182
<br />6,701
<br />757
<br />481
<br />Well -5
<br />1325665
<br />350095
<br />7,450
<br />7,274
<br />6,780
<br />675
<br />494
<br />Well -6
<br />1326892
<br />347972
<br />7,748
<br />7,467
<br />6,988
<br />765
<br />479
<br />Well 7
<br />1328213
<br />347757
<br />7,730
<br />7,470
<br />6,975
<br />760
<br />495
<br />Well -8
<br />1329328
<br />348177
<br />7,436
<br />7,403
<br />6,882
<br />559
<br />521
<br />Well -9
<br />1330356
<br />347375
<br />7,724
<br />7,426
<br />6,938
<br />791
<br />488
<br />Well -10
<br />1331738 1
<br />348894
<br />7,566
<br />7,209
<br />6,744
<br />827
<br />465
<br />AVERAGE
<br />740
<br />487
<br />The effects of dewatering on the Collom Pit in Scenario 2 are presented in Figures 7a j.
<br />The figures display results along the same vertical section discussed above. This case also
<br />represents the previously identified optimal lag of 3 years between the start of mining and the
<br />onset of dewatering. Figures 7a, 7b, and 7c display the progress of the box -cut development at
<br />the end of years 5, 7 and 9, along with the concurrent lowering of the water table due to the
<br />dewatering that was initiated at the end of the 3rd of year of mining. Figure 7d presents the pit
<br />configuration at the end of the 12th year of mining, after which the upslope pumping wells (#6, 7,
<br />8, and 9) are assumed to be destroyed during stripping. Figures 7e, 7f, 7g, 7h, 7i, and 7j
<br />represent snapshots of the pit geometry and state of the corresponding dewatering at the end of
<br />years 15, 20, 25, 30, 35, and 38, respectively. In all the analyzed intervals of mining, pre- and
<br />post-box cut, the water table was found to have been drawn below the pit floor. Even after the
<br />Agapito Associates, Inc.
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