PERMFILE61228

• Permit No: C1996084A
• IBM Index Class Name: Permit File
• Doc Date: 7/5/2002
• Section_Exhibit Name: Section 2.05 Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

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Rule 1' Permits
The crushed gravel will be durable to withstand the anticipated volume oftraffic. Noacid-ortoxic-forming
substances will be used in haul road surfacing. In addition to improving the gravel running surface, this
measure will provide stability to the haul road.
The triangular-shaped berm on the outside edge of the roadway will be no less in height than the mid-axle
height ofa haul truck, approximately 48-inches high, with side slopes no steeper than 2h: l v. The berm does
not infringe upon the gravel travel way. Gaps in the berm will be provided at cross-culvert locations, but in
no case does spacing exceed 1,500 feet. The controlled spacing will provide positive drainage off the
roadway to promote stability.
Drainage ditches will be placed at the toe of all cut slopes and intercept Flows before switchbacks or large
fills. Ditcheswill be sized to accommodate l0-year 24-hour design Flows with 0.3 feet of freeboard. Flow
velocities wi I I be limited to the characteristicsofsoils without recourse to design riprap or other ditch linings
by relief drains (culverts) crossing under the roadway.
Culverts wil I be placed at crossings of watershed drainages and ditch rel iefcross-culverts to transfer runoff
across (under) the roadway. Culverts will be designed to sustain [he vertical soil pressure, foundation
conditions, and weight ofvehicles. A minimum of I foot ofcoverover culverts is specified by the regulations,
but may be larger based on Table 2.05.3-1. All culverts have mitered inlets, unless additional protection is
needed to minimize erosion. Culverts across watershed natural drainages will be placed at channel grade to
promote conveyance of design Flow, to not affect the normal flow or gradient of the stream, and to not
adverselyaffectaquatichabitorrelatedenvironmentalvalues. Cross-culvertswillbeplacedataninver[slope
of 2 to 3%.
TABLE 2.05.3-1
LORENCITO CANYON MINE
MINIMUM COVER RECOMMENDATIONS'
Diameter of Culvert (inches) Minimum Cover (feet)
12-42 3.0
48-72 4.0
78-120 4.0
Handbook oJS~eel Drainage & Highway Construction Products, American /ron and Steel Institute (172 Kip
maximum for 777C tractor rear axle reduced [o I50 or less for coal loads.)
Culverts will be designed to transfer peak runoff from a 10-yeaz, 24 hour precipitation event. Ifa design
culvert end azea exceeds 35 squaze feet, capacity is increased to a 20-yeaz, 24-hour precipitation event.
AI I culverts will be sized to accommodate design flows without a head over the conduit. However, the
minimum diameter is 18 inches to minimize plugging and accommodate maintenance. Somedrainage
structures will be located on ephemeral, intermittent, or perennial streams with watersheds ofmore than
one squaze mile. M alternate design proposed is a hybrid drainage structure that employs both culvert and
ford characteristics. These hybrid drainage structures (Arizona crossing) aze designed to pass the 2-yeaz,
P~-0,
LormcnoPmo-PAfTN)5)Iu1y3001 wpd
2.05-22
(Revised 7/25/01)