2010-12-17_REVISION - C1981019 ‎(140)‎

• Permit No: C1981019
• IBM Index Class Name: REVISION
• Doc Date: 12/17/2010
• Doc Name: Exhibit 7 Item 22 Collom Pit Regional Hydrogeologic Model
• Type & Sequence: PR3
• Email Name: JRS
• Media Type: D
• Archive: No

DRAFT
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CONTENTS
Page
1 INTRODUCTION 1
2 HYDROLOGICAL SYSTEM AND AVAILABLE DATA 3
2.1 Hydrogeologic units 3
2.2 Controls on groundwater flow 4
2.3 Groundwater gradients and pressures 7
2.4 Water balance 7
3 MODEL DEVELOPMENT 11
3.1 Choice of modeling code 11
3.2 Finite element mesh 11
3.3 Model layer surfaces 11
3.4 Storage 14
3.5 Structures 14
3.6 Boundary conditions 15
3.7 Recharge 15
3.8 Calibration targets 16
4 MODEL CALIBRATION 17
4.1 Approach 17
4.2 Steady-state calibration 17
4.3 Transient calibration 20
TABLES
2.1 Summary of measured hydraulic conductivities 4
2.2 Estimated independent water balance for Collom area 10
4.1 Groundwater recharge/discharge summary from water balance and
regional model 19
4.2 Calibrated hydraulic parameters from transient calibration 20
2572-R3
Water Management Consultants
Colowyo Coal Company, L.P.