2022-04-04_PERMIT FILE - M2022013 ‎(38)‎

• Permit No: M2022013
• IBM Index Class Name: Permit File
• Doc Date: 4/4/2022
• Doc Name Note: Exhibit G - Flood Control Mitigation Plan
• Doc Name: Application
• From: Varra Companies, Inc.
• To: DRMS
• Email Name: RDZ
• Email Name: MAC
• Media Type: D
• Archive: No

Two Rivers Gravel Pit Mine
Riverside Berm Failure Analysis
and Flood Control Mitigation Plan
7ech"olooicess January 22,2020
TABLE OF CONTENTS
DISCLAIMER 3
ABSTRACT 4
PURPOSE 5
I. INTRODUCTION 6
II. SITE DESCRIPTION 6
III. STUDY METHODOLOGY 9
IV. RESULTS 15
IV. MITIGATING MEASURES 21
VI. WATER SURFACE PROFILE FOR SOUTH PLATTE RIVER ALONG 21
CENTRAL PIT
VII. SUMMARY AND CONCLUSIONS 23
REFERENCES 24
APPENDIX 25
LIST OF FIGURES
Figure 1. Two Rivers. Vicinity map. 7
Figure 2. Two Rivers. Site map. 7
Figure 3. Two Rivers. FEMA 100-yr floodplain. 9
Figure 4. Central Pit. Pit fill time and water surface elevation vs. head cut elevation 17
for
100 ft riverside berm.
Figure 5. Central Pit. Pit fill time and water surface elevation vs. head cut elevation 18
for
150 ft riverside berm.
Figure 6. Central Pit. Pit fill time and water surface elevation vs. head cut elevation 19
for
200 ft riverside berm.
Figure 7. Pit fill time and water surface elevation vs. head cut elevation for a typical 20
riverside berm.
Figure 8. Central Pit. South Platte River 100-yr water surface profile. 22
Figure 9. River stations for Figure 8. 22
pg.2