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JD -8 Mine - Drainage Design Plan i <br />TABLE OF CONTENTS <br />1. INTRODUCTION 1 <br />1.1 Purpose 1 <br />1.2 Background - Lower Runoff Areas and Routing 1 <br />1.3 Background - Upland Runoff Areas 2 <br />2. DESIGN CRITERIA AND METHODOLOGY 5 <br />2.1 Design Storms 5 <br />2.2 Run -on / Run -off Volumetric Estimates 5 <br />2.3 Run -on / Run -off Peak Discharge Estimates 6 <br />2.4 Channel Design 6 <br />2.5 Culvert Design 6 <br />2.6 Spillway Design 6 <br />2.7 Riprap / Granular Bedding / Gravel Mulch 6 <br />3. DIVERSION DRAINAGE 7 <br />3.1 Storm Water Routing from Upland Areas 7 <br />3.2 100 -year 24 -hour Routing Capacity for Upland Areas 7 <br />3.3 10 -year 24 -hour Runoff and Retention for Affected Area 9 <br />3.4 100 -year 24 -hour Routing Capacity 10 <br />4. OPERATIONAL AND POST - MINING DRAINAGE CONDITIONS 11 <br />4.1 Runoff Areas and Routing 11 <br />4.2 10 -year 24 -hour Runoff and Retention for Post - Mining Condition 13 <br />4.3 100 -year 24 -hour Routing Capacity 13 <br />5. REFERENCES 16 <br />LIST OF TABLES <br />Table 1. Sub -Basin Areas at the JD -8 Mine under Current Conditions 1 <br />Table 2. Upland Non - Contributing Drainage Areas 2 <br />Table 3. Recurrence Interval for Design Storms 5 <br />Table 4. Non - Contributing Drainage Peak Discharge (Qioo) 8 <br />Table 5. Diversion Drainage Structure Parameters 8 <br />Table 6. Site Runoff for 10 -yr 24 -hour Storm Calculated Using SCS Method 9 <br />Table 7. Planned Dimensions for Storm Water Retention Pond 1 10 <br />Table 8. Planned Dimensions for the Expanded Storm Water Retention Pond 2 10 <br />Table 9. Mine Site Current Conditions - Peak Discharge (Q 10 <br />Table 10. Mine Site Planned Drainage Structure Parameters 11 <br />Table 11. Drainage Basin Areas - Planned Final Topography 13 <br />Table 12. Calculated 10 -year 24 -hour Runoff based on Planned Final Topography 13 <br />4122A.120702 Whetstone Associates • <br />