2020-07-13_REVISION - C1981008 ‎(2)‎

• Permit No: C1981008
• IBM Index Class Name: Revision
• Doc Date: 7/13/2020
• Doc Name: Adequacy Review Response
• From: Elk Ridge Mining and Reclamation, LCC
• To: DRMS
• Type & Sequence: TR99
• Email Name: JHB
• Email Name: THM
• Media Type: D
• Archive: No

Table 2.05.3(3)-1 Surface Hydrology Curve Numbers
Hydrologic Curve
Condition Number
Mine Disturbed Areas:
Newly Graded Areas' Poor 83
Roads N/A 85
Reclaimed Areas:
Topsoiled and seeded' Poor 83
Topsoil Stockpiles' Poor 80
1-2 years revegetation2 Fair 74
3+years revegetation3 Good 62
Source: Part 630 Hydrology, National Engineering Handbook, Chapter 9 (USDA/NSCS, July
2004)
1. Curve number based on an average of"Fallow, with Crop Residue, Poor Condition",
Table 9-1, with 50% HSG A and 50% HSG B and conservatively revised upward.
2. Curve number based on an average of"Pasture or Range, Fair Condition", Table 9-1,
with 50% HSG A and 50% HSG B and conservatively revised upward.
3. Curve number based on an average of"Pasture or Range, Good Condition", Table 9-1,
with 50% HSG A and 50% HSG B conservatively revised upward.
Section 2.05.3(3) Page 10 July 2020 (TR-99)