2013-10-31_REVISION - M1977284 ‎(3)‎

• Permit No: M1977284
• IBM Index Class Name: REVISION
• Doc Date: 10/31/2013
• Doc Name: Drainage Design Plan Mineral Joe Mine
• From: Cotter
• To: DRMS
• Type & Sequence: AM1
• Email Name: TC1
• Email Name: SJM
• Media Type: D
• Archive: No

Mineral Joe Mine - Drainage Design Plan 22
4.4.3 Lower Diversion Structure (LDS)
The LDS diverts non - contact stormwater to the east and north, around the Duggan adit and the central mine
facilities area. The northern segment of the LDS (LDS -N) routes water northward approximately 335 feet,
where it crosses the access road and enters the stormwater retention pond (SWRP). The eastern segment
(LDS -E) collects stormwater runoff from sub -basin N -E and diverts it eastward approximate 255 feet
around the mine facilities (Figure 1).
The LDS -N and LDS -E channels were inspected on May 28, 2013 and ten cross sectional profiles were
surveyed (Plate 5). The survey results are presented in Attachment 3 and are summarized in Table 13.
The LDS -E channel is broad and shallow, with an average top width of 12.8 feet and an average side slope
ratio of 3.4:1. The average local bedslope is 0.0397 for the four LDS -E profiles and 0.0800 for the entire
channel. Based on the surveyed channel geometry, the current LDS -E was modeled with a 1.8 -ft bottom
width and 3.4:1 ft side slopes in the WinTR -55 model run CC_CP 03.w55.
The LDS -N channel is broad and shallow, with an average top width of 13.4 feet and an average side slope
ratio of 3.1:1. The channel is slightly eccentric, with the left bank typically steeper than the right bank.
The average local bedslope is 0.0711 for the six LDS -N profiles and 0.0794 for the entire channel. Based
on the surveyed channel geometry, the current LDS -N was modeled with a 1.7 -ft bottom width and 3.4:1 ft
side slopes in the WinTR -55 model run CC_CP- 03.w55. Model results are presented in Section 5.2
(channel capacity) and 5.3 (channel stability).
Table 13. Lower Diversion Structure Channel Geometry
Profile ID:
LDS -E -PI
LDS -E -P2
LDS -E -P3
LDS -E -P4
Avg.
Area, bank full (ft2):
10.32
13.25
7.37
35.02
16.5
Area,0.5-ft freeboard (ft2):
4.58
7.51
2.78
28.32
10.8
Area,l -ft freeboard (ft2):
1.04
3.15
0.16
21.92
6.6
Top Width (ft):
13.70
12.8
10.75
14.00
12.8
Bottom Width (ft):
3.75
2.75
0.80
0.00
1.8
Side Slope Ratio, Left Bank:
5.71
4.05
6.05
2.32
4.5
Side Slope Ratio, Right Bank:
2.46
2.41
3.00
1.12
2.2
Average Side Slope Ratio:
4.1
3.2
4.5
1.7
3.4
Local Channel Bed Slope (ft):
0.0441
0.0215
0.0223
0.0707
0.0397
Profile ID:
LDS -N -PI
LDS -N -P2
LDS -N -P3
LDS -N -P4
LDS -N -P5
LDS -N -P6
Avg.
Area, bank full (ft2):
11.63
14.82
19.87
11.08
22.41
7.41
14.5
Area,0.5 -ft freeboard (W):
5.76
8.93
12.93
6.32
16.48
1.97
8.7
Areal -ft freeboard (ft'):
1.87
4.66
8.19
3.59
11.69
0.08
5.0
Top Width (ft):
14.30
13.30
14.85
10.50
13.30
13.90
13.4
Bottom Width (ft):
2.85
0.90
1.80
1.85
1.40
1.50
1.7
Side Slope Ratio, Left Bank:
1.83
1.35
1.59
1.84
1.09
3.55
1.9
Side Slope Ratio, Right Bank:
6.23
3.60
3.12
2.40
2.42
8.42
4.4
Average Side Slope Ratio:
4.0
2.5
2.4
2.1
1.8
6.0
3.1
Local Channel Bed Slope (ft):
0.04067
0.0407
0.1276
0.0637
0.0803
0.0739
0.0711
4148B.131029 Whetstone Associates