2011-06-06_REVISION - M1984014 ‎(7)‎

• Permit No: M1984014
• IBM Index Class Name: Revision
• Doc Date: 6/6/2011
• Doc Name: Amendment App. ‎(AM-01)‎ Attachment A Drainage Plan, Rule 6.5 & Spill Prevention
• From: Cotter Corporation
• To: DRMS
• Type & Sequence: AM1
• Email Name: GRM
• Media Type: D
• Archive: No

JD-8 Mine - Drainage Design Plan 6
•
The curve number of 85 was obtained from Table 2-2d Runoff Curve Numbers for Arid and Semi-Arid
Rangelands of TR-55, based on hydrologic soil group C3, a vegetative cover of sagebrush with grass
understory, and a "Poor" hydrologic condition. Using these parameters, the calculated runoff values for
the 10-year 24-hour and 100-year 24-hour design storms are shown in Table 4 and Table 5, respectively.
Table 4. Runoff from Site Basins for 10-yr 24-hour Storm Calculated Using SCS method
for Design Storms
Hydr. Condition Area Curve Rainfall Retention Runoff Runoff
Soil Type Area Group Cover Description (acres) Number P
S Q Q
CN inches inches ft
Bodot / Ustic 1 C Sagebrush w/grass Fair 15
1 63 1
80 5
87 0
06 251
Torriorthents understo . . . .
Bodot / Ustic 2 C Sagebrush w/grass Poor 1.14 85 1.80 1.76 0.65 2
698
Torriorthents understo ,
3 Receiving Area 0.57 63 1.80 5.87 0.06 125
Bodot / Ustic
4
C Sagebrush w/grass
Fair
1
69
63
1
80
5
87
0
06
369
Torriorthents understo . . . .
Bodot / Ustic 5 C Sagebrush w/grass Poor 3.16 85 1.80 1.76 0.65 479
7
Torriorthents understo ,
6 Receiving Area 0.18 63 1.80 5.87 0.06 39
(Constructed catchment)
Total runoff to receiving area 3: 0.16 acre-ft (6,950 ft3, 51,960 gallons)
Total runoff to receiving area 6: 0.37 acre-ft (16,330 ft3, 122,000 gallons)
• Total runoff from site: 0.53 acre-ft (23,270 ft3, 174,000 gallons)
Table 5. Runoff from Site Basins for 100-yr 24-hour Storm Calculated Using SCS method
for Design Storms
H dr.
Condition Area Curve Rainfall Retention Runoff Runoff
Soil Type Area Group Cover Description (acres) Number P S Q Q
'
CN inches inches ft
Bodot / Ustic 1 C Sagebrush w/grass Fair 1.15 63 2.60 5.87 0.28 1
162
Torriorthents understo ,
Bodot / Ustic 2 C Sagebrush w/grass Poor 1.14 85 2.60 1.76 1.26 5
208
Torriorthents understo ,
3 Receiving Area 0.57 63 2.60 5.87 0.28 576
Bodot / Ustic 4 C Sagebrush w/grass Fair 1.69 63 2.60 5.87 0.28 1
708
Torriorthents understo ,
Bodot / Ustic 5 C Sagebrush w/grass Poor 3.16 85 2.60 1.76 1.26 14
437
Torriorthents understo ,
6 Receiving Area 0
18 63 2
60 5
87 0
28 182
(Constructed catchment) . . . .
Total runoff to receiving area 3: 0.07 acre-ft (3,074 ft3, 23,000 gallons)
Total runoff to receiving area 6: 0.18 acre-ft (7,900 ft3, 59,000 gallons)
Total runoff from site: 0.25 acre-ft (11,000 ft3, 82,000 gallons)
• 3 Site soils consist of Bodot and Ustic Torriorthents, which is listed as hydrologic soil group C in the NRCS Web Soil Survey
(MRCS, 2011).
4122A.110601 Whetstone Associates