2018-02-05_PERMIT FILE - C1981019

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 2/5/2018
• Doc Name: Collom Pit Dewatering Study November 2017
• Section_Exhibit Name: Exhibit 07 Item 22B
• Media Type: D
• Archive: No

October 19, 2017
COLLOM PIT DEWATERING STUDY
TABLE OF CONTENTS
Page i
Paye
EXECUTIVE SUMMARY........................................................................................................ES-1
1.0 INTRODUCTION................................................................................................................1
1.1 Project Background and Setting...............................................................................1
1.1.1 Project Location and Topography................................................................1
1.1.2 Geologic Setting...........................................................................................1
1.2 Collom Pit Mine Plan...............................................................................................2
2.0 COLLOM PIT DEWATERING EVALUATION..............................................................4
2.1
Previous Dewatering Study......................................................................................4
Pilot Test Pumping Schedule used in Calibration..........................................................9
Table 3.
2.1.1 Collom Project Pre -feasibility Hydrology Report
.......................................4
Regional Baseline Water Elevations............................................................................1 l
2.1.2 Collom Project Geotechnical Study Report.................................................4
Well Locations, Depths, and Screened Lengths: Scenario 1
......................................19
2.1.3 Summary of AAI Review of Previous Studies...........................................4
Well Locations, Depths, and Screened Lengths: Scenario 2
2.2
Collom Site Visit......................................................................................................5
Water Discharge Pipeline Design Data: Scenario 1 ....................................................45
2.3
Dewatering Study Approach and Model Development...........................................5
Table 9.
2.4
Calibration of Strata Hydraulic Parameters.............................................................6
Monitoring Well Locations and VWP Depths: Scenario 2 ..........................................46
2.5
Collom Pit Dewatering Predictive Analyses and Results......................................10
2.6
Water Discharge Pipeline Layout..........................................................................42
2.7
Monitoring Well Design........................................................................................46
3.0 SUMMARY OF RESULTS AND RECOMMENDATIONS.............................................48
4.0 REFERENCES..................................................................................................................49
APPENDIX A ---SUMMARY OF MEASURED HYDRAULIC CONDUCTIVITIES ............................... A-1
LIST OF TABLES
Page
Table 1.
Simulated Collom Area Layers......................................................................................8
Table 2.
Pilot Test Pumping Schedule used in Calibration..........................................................9
Table 3.
Summary of Calibrated Hydraulic Parameters..............................................................9
Table 4.
Regional Baseline Water Elevations............................................................................1 l
Table 5.
Well Locations, Depths, and Screened Lengths: Scenario 1
......................................19
Table 6.
Well Locations, Depths, and Screened Lengths: Scenario 2
......................................19
Table 7.
Water Discharge Pipeline Design Data: Scenario 1 ....................................................45
Table 8.
Water Discharge Pipeline Design Data: Scenario 2 ....................................................45
Table 9.
Monitoring Well Locations and VWP Depths: Scenario 1 ..........................................46
Table 10.
Monitoring Well Locations and VWP Depths: Scenario 2 ..........................................46
Agapito Associates, Inc.