PERMFILE70287

• Permit No: M1997026
• IBM Index Class Name: Permit File
• Doc Name: MINING PLAN AND TIMETABLE EXHIBIT D
• Section_Exhibit Name: EXHIBIT D
• Media Type: D
• Archive: No

EXHIBIT D -MINING PLAN (continued)
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during the irrigation Flow period is approximately 6-12 inches and the vegetation consists almost
entirely of grasses. The crossing would be made by first installing the designed corrugated metal
culvert and then compacting road base material to a height of 24" above the top of the culvert. The
road width is expected to be 30 feet to handle traffic in both directions.
Once the areas east and west of the unnamed drainage are mined, the area draining to the culvert
location will be severely limited, however, doting initial site startup, the area draining to the culvert
will be 5.2 acres, which are located north of the south berm. The culvert is designed for the 100
year - 24 hour event peak flow using the STORM program developed by the technical branch of the
Office of Surface Mining. The design is given below:
WATERSHED HYDROGRAPH
Inflow into structure # 1
Structure type: Null
100 year - 24 hour precipitation: 2.4 inches
Curve Number of Site: (assuming worst case acreage disturbed at any one time) - ~.2 acres
disturbed porous gravel. CN = 79
time of concentration path: 930' long, 40' drop, short grass pasture
Using these inputs, the STORM program produced the following results:
Project Title = Carol Ann Permit Culvert Crossing
-- Watershed data for watershed # 1
Curve number = 79 0
Area
Hydraulic length
Elevation change
Concentration time
Concentration time type
Unit hydrograph type
-- Total Area
= 6.2 acres
= 890.00 Feet
= 30.0 feet.
= 0.19 hours
= SCS Upland Curves
= Disturbed
= 6.2 acres
-- Storm data
Total precipitation = 2.4 inches
Storm type = SCS Type 2 storm, 24 hour storm
Peak Discharge = 4.09 cfs
Discharge volume = 0.40 acre ft
Cazol Ann Pernut CDMG AppLcanon
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