2012-02-28_REVISION - M1980244 ‎(80)‎

• Permit No: M1980244
• IBM Index Class Name: REVISION
• Doc Date: 2/28/2012
• Doc Name: VOL 6, Part 4: Storm Water Management Plan
• From: CC&V
• To: DRMS
• Type & Sequence: AM10
• Media Type: D
• Archive: No

TABLE OF CONTENTS
STORM WATER MANAGEMENT PLAN — MLE2 — AMENDMENT NO 10 — FOR
AREAS EXCLUDING AREQUA GULCH VLF AND SQUAW GULCH VLF 1
1. Storm water Hydrology 2
Inflow Design Storms and Design Criteria 2
Runoff Coefficients 2
Hydrology Calculations and Sizing of EMP Ponds and Channels 4
2. Sediment Removal Efficiency and Performance 5
3. Storm Water Management Plan for Upper Grassy Valley 7
Flow Schematic 8
Special Considerations for Upper Grassy Valley Storm Water Management 9
4. Storm Water Management Plan for the West Side of the Mine, Including North Cresson and
Poverty Gulch 11
Flow Schematic 12
Special Considerations for Upper Grassy Valley Storm Water Management 13
TABLES
Table I Summary of Hydrology Calculations for EMP Sizes Using Geometric Land -use
Averaging 16
FIGURES
Figure 1 — Upper Grassy Valley and Vindicator Valley, Storm Water Flow Schematic 8
Figure 2 — Poverty Gulch and North Cresson, Storm Water Flow Schematic 12