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 2
vent holes and roads leading to the vent holes. Due to its close proximity to the JD -6 Mine, some of the
stormwater management performed at the Mineral Joe Mine site is beneficial to both properties. However,
the two sites operate under separate mine permits and stormwater management plans. Specifically, the
stormwater diversion structures which are associated with the JD -6 Mine are also beneficial in reducing
run -on to the Mineral Joe Mine facilities, while the stormwater retention pond associated with the Mineral
Joe Mine collects runoff from the JD -6 waste rock pile.
2. DESIGN CRITERIA & METHODOLOGY
2.1 Design Storms
The magnitudes of design storms for the site are shown in Table 2. The rainfall intensities for 24 -hour
storms with 2 -year to 100 -year recurrence intervals were interpolated from the NOAA Atlas 2, Vol. III
(USDC, 1973), for the purpose of runoff calculations and engineering design. Per DRMS
recommendations, control structures for the Mineral Joe Mine presented in this design report are
engineered to contain the 10 -year 24 -hour storm event and safely pass a 100 -year 24 -hour storm event.
Table 2. Design Storm Parameters
Recurrence
Interval
Duration
(Hours)
Storm Magnitude
NOAA Atlas
inches
100- ear
24
3.0
50-year
24
2.7
25-year
24
2.4
10- ear
24
2.0
5-year
24
1.6
2-year
24
1.2
2.2 Runoff Estimates
2.2.1 Volume
Catchment runoff was estimated using Technical Release 55 (TR -55) developed by the U. S. Department of
Agriculture Natural Resources Conservation Service (NRCS, 1986). TR -55 presents simplified procedures
to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for
floodwater reservoirs in small watersheds.
Runoff depth (qd) is calculated in TR -55 by the Curve Number (CN) method, using the following equation:
__ (P- 0.2S)Z
q`' (P +0.8S)
where: qd = Runoff depth, inches (qd = 0, if P < 0.2S),
P = Rainfall depth, inches
S = Potential maximum rainfall retention after runoff begins, inches
This method assumes initial abstraction (losses before runoff begins due to retention in surface depressions,
interception by vegetation, evaporation, infiltration, etc.) is equal to 0.2S.
The parameter S is related to curve number (CN) by:
4148B.131029 Whetstone Associates