2011-08-29_REVISION - M2005050 ‎(6)‎

• Permit No: M2005050
• IBM Index Class Name: REVISION
• Doc Date: 8/29/2011
• Doc Name: Submittal
• From: Rimrock Exploration and Development, Inc.
• To: DRMS
• Type & Sequence: TR2
• Email Name: GRM
• Media Type: D
• Archive: No

JBIRD MINE 24HR 10 YR STORM DETENTION & 24HR 100YR STORM - PEAK FLOW
The following calculations are for pond /weir sizing only, for the revised mine permit area of disturbance at the new portal.and
lower dump areas. Peak flows were derived using TR -55. Hydrologic soil type is Group D (clayey soil with impervious
underlayment and high runoff potential). Land type is rural pinon /juniper arid rangeland.
The basin is sized to contain the 10 year event with the overflow sized to pass the 100 year flow.
BASIN AREA(SF) AREA(AC) C100
U -1 31741 0.729 0.83
U -2 65998 1.52 0.72
L -1 130584 2.985 0.72
From the weir formula -
which becomes -
UPPER POND - DESIGN CAPACITY
DETENTION BASIN SIZING - 10YR 24HR EVENT 6697.0 2638.7 6066.0 6021.4
AREA(AC) C10 D10 V10 WEIR
UPPER POND 6696.1 2093.6 3936.5 3896.6
0.729 0.76 1.9 3821.214 6696.0 2015.1 3731.0 3691.1
6695.0 1523.1 1961.9 1927.8
NEW LOWER AREA 6694.0 1011.3 694.7 669.2
6693.0 378.1 0.0 0.0
2.985 0.67 1.9 13793.655
I values are derived from the NOAA Atlas 2 tables.
where -
Q = CLH3 /2
L= Q /CH3 /2
H = (Q / CL) ^2/3
C = (2/3)3/2(g)1/2
Q - flow in cfs,
L - width of weir in feet,
g - gravitational constant- 32.2fpsps
1100
6.18
6.18
6.18
Q100
3.7
6.7
13.3
LOWER POND - DESIGN CAPACITY
6638.0 6736.3 16460.9 16339.
WEIR
6637.6 6094.5 13894.7 13774.
6637.0 5243.0 10493.5 10376.
6636.0 3473.0 6135.5 6049.1
6635.0 2223.1 3287.4 3224.1
6634.0 1288.4 1531.6 1489.5
6633.0 786.4 494.2 462.4
6632.0 202.1 0.0 0.0